<PAGE>
 
                                                                    EXHIBIT 10.5

                                                              EXECUTION ORIGINAL



       INTERCONNECTION AGREEMENT UNDER SECTIONS 251 AND 252 OF THE
                       TELECOMMUNICATIONS ACT OF 1996

                         Dated as of January 29, 1997/1/
                                                      -

                                by and between

                    AMERITECH INFORMATION INDUSTRY SERVICES,
                    a division of Ameritech Services, Inc.
               on behalf of and as agent for Ameritech Michigan

                                      and

                 FOCAL COMMUNICATIONS CORPORATION OF MICHIGAN



____________________________

/1/     See Footnote 21 on Signature Page.
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                               TABLE OF CONTENTS

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ARTICLE I
     DEFINITIONS AND CONSTRUCTION...........................        2
     1.1   Structure........................................        2
     1.2   Defined Terms....................................        2
     1.3   Interpretation...................................        2
     1.4   Joint Work Product...............................        2
     1.5   Regional Matters.................................        3

ARTICLE II
     GENERAL SERVICE RELATED PROVISIONS.....................        3
     2.1   Interconnection Activation Date..................        3
     2.2   Bona Fide Request................................        4
     2.3   Technical References.............................        4
     2.4   Use of Services..................................        4

ARTICLE III
     INTERCONNECTION PURSUANT TO SECTION 251(c)(2)..........        4
     3.1   Scope............................................        4
     3.2   Interconnection Points and Methods...............        5
     A3.2  Focal Alternative Methods of Interconnection.....        5
     B3.2  Ameritech Alternative Methods of Interconnection.        6
     C3.2  SS7 Interconnection..............................       10
     3.3   Fiber-Meet.......................................       11
     3.4   Interconnection in Additional LATAs..............       13
     3.5   Additional Interconnection in Existing LATAs.....       13
     3.6   Nondiscriminatory Interconnection................       13
     3.7   Network Management...............................       14
     3.8   Standards of Performance.........................       14
     3.9   9-1-1 Service....................................       15

ARTICLE IV
     TRANSMISSION AND ROUTING OF TELEPHONE EXCHANGE
     SERVICE TRAFFIC PURSUANT TO SECTION 251(c)(2)..........       18
     4.1   Scope of Traffic.................................       18
     4.2   Limitations......................................       18
     4.3   Trunk Group Architecture and Traffic Routing.....       19
     4.4   Signaling........................................       19
     4.5   Grades of Service................................       20
     4.6   Measurement and Billing..........................       20
     4.7   Reciprocal Compensation Arrangements -- Section 
               251(b)(5)....................................       21
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ARTICLE V
     TRANSMISSION AND ROUTING OF EXCHANGE ACCESS TRAFFIC 
     PURSUANT TO 251(c)(2)..................................       22
     5.1   Scope of Traffic.................................       22
     5.2   Trunk Group Architecture and Traffic Routing.....       22

ARTICLE VI
     MEET-POINT BILLING ARRANGEMENTS........................       22
     6.1   Meet-Point Billing Services......................       22
     6.2   Data Format and Data Transfer....................       23
     6.3   Errors or Loss of Access Usage Data..............       24
     6.4   Payment..........................................       24
     6.5   Additional Limitations of Liability Applicable 
               to Meet-Point Billing Arrangements...........       24

ARTICLE VII
     TRANSPORT AND TERMINATION OF OTHER TYPES OF TRAFFIC....       25
     7.1   Information Services Traffic.....................       25
     7.2   BLV/BLVI Traffic.................................       26
     7.3   Transit Service..................................       26

ARTICLE VIII
     INSTALLATION, MAINTENANCE, TESTING AND REPAIR..........       28
     8.1   Plan.............................................       28
     8.2   Operation and Maintenance........................       28
     8.3   Installation, Maintenance, Testing, and Repair...       29
     8.4   Additional Terms.................................       29

ARTICLE IX
     UNBUNDLED ACCESS -- SECTION 251(c)(3)..................       29
     9.1   Access to Network Elements.......................       29
     9.2   Network Elements.................................       30
     9.3   Combination of Network Elements..................       30
     9.4   Nondiscriminatory Access to and Provision of
               Network Elements.............................       32
     9.5   Provisioning of Network Elements.................       32
     9.6   Availability of Additional or Different Quality
               Network Elements.............................       33
     9.7   Pricing of Unbundled Network Elements............       33
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     9.8   Billing..........................................       34
     9.9   Maintenance of Unbundled Network Elements........       34
     9.10  Standards of Performance.........................       34

ARTICLE X
     RESALE AT WHOLESALE RATES -- SECTION 251(c)(4).........       36
     10.1  Telecommunications Services Available for Resale
               at Wholesale Rates...........................       36
     10.2  Other Services...................................       37
     10.3  Limitations on Availability of Resale Services...       37
     10.4  Additional Charges for Resale Services...........       38
     10.5  Restrictions on Resale Services..................       38
     10.6  New Resale Services; Changes in Provision of
               Resale Services..............................       39
     10.7  Operations Support Systems Functions.............       39
     10.8  Nondiscriminatory Provision of Resale Services...       39
     10.9  Standards of Performance.........................       39
     10,10 Branding.........................................       41
     10.11 Primary Local Exchange and Interexchange Carrier
               Selections...................................       42
     10.12 Functionality Required To Support Resale Service.       44
     10.13 Service Functions................................       44
     10.14 Responsibilities of Focal........................       47
     10.15 Responsibilities of Ameritech ...................       47
     10.16 Exchange of Billing Information..................       48
     10.17 Use of Service...................................       49

ARTICLE XI
     NOTICE OF CHANGES -- SECTION 251(c)(5).................       50

ARTICLE XII
     COLLOCATION -- SECTION 251(c)(6).......................       50
     12.1  Physical Collocation.............................       50
     12.2  Virtual Collocation in Physical Collocation 
               Space........................................       50
     12.3  Virtual Collocation in Virtual Collocation Space.       50
     12.4  Nondiscriminatory Collocation....................       51
     12.5  Eligible Equipment...............................       51
     12.6  Transmission Facility Options....................       51
     12.7  Interconnection with other Collocated Carriers...       51
     12.8  Interconnection Points and Cables................       52
     12.9  Allocation of Collocation Space..................       52
     12.10 Security Arrangements............................       53
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     12.11 Subcontractor and Vendor Approval................       53
     12.12 Delivery of Collocated Space.....................       53
     12.13 Pricing .........................................       57
     12.14 Billing..........................................       57
     12.15 Common Requirements..............................       57
     12.16 Additional Requirements..........................       57
     12.17 Protection of Service and Property...............       57
     12.18 Standards of Performance.........................       58

ARTICLE XIII
     NUMBER PORTABILITY -- SECTION 251(b)(2)................       58
     13.1  Provision of Local Number Portability............       58
     13.2  Interim Number Portability ("INP")...............       58
     13.3  Remote Call Forwarding ("RCF")...................       58
     13.4  Direct Inward Dialing............................       59
     13.5  NXX Migration....................................       60
     13.6  Other Interim Number Portability Provisions......       60
     13.7  Compensation on Traffic to INP'ed Numbers........       61
     13.8  Pricing For Interim Number Portability...........       62
     13.9  Permanent Number Portability.....................       62
     13.10 Other INP Methods................................       62

ARTICLE XIV
     DIALING PARITY-- SECTIONS 251(b)(3) and 271(e)(2)(B)...       62

ARTICLE XV
     DIRECTORY LISTINGS -- SECTION 251(b)(3)................       62
     15.1  Directory Listings...............................       62
     15.2  Listing and Listing Updates......................       63

ARTICLE XVI
     ACCESS TO POLES, DUCTS, CONDUITS AND RIGHTS-OF-WAY
           -- SECTIONS......................................       64
     16.1  Structure Availability...........................       64
     16.2  Franchises, Permits and Consents.................       65
     16.3  Access and Modifications.........................       65
     16.4  Installation and Maintenance Responsibility......       66
     16.5  Installation and Maintenance Standards...........       67
     16.6  Implementation Team..............................       67
     16.7  Access Requests..................................       67
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     16.8  Unused Space.....................................       67
     16.9  Maintenance Ducts................................       67
     16.10 Applicability....................................       67
     16.11 Other Arrangements...............................       68
     16.12 Cost of Certain Modifications....................       68
     16.13 Maps and Records.................................       68
     16.14 Focal Access.....................................       68
     16.15 Occupancy Permit.................................       68
     16.16 Inspections......................................       69
     16.17 Damage to Attachments............................       69
     16.18 Charges..........................................       69
     16.19 Nondiscrimination................................       69
     16.20 Interconnection..................................       69
     16.21 Cost Imputation..................................       69
     16.22 Structure Leasing Coordinator....................       70
     16.23 State Regulation.................................       70
     16.24 Abandonments, Sales or Dispositions..............       70
     16.25 Standards of Performance.........................       70

ARTICLE XVII
     REFERRAL ANNOUNCEMENT..................................       70

ARTICLE XVIII
     IMPLEMENTATION TEAM AND IMPLEMENTATION PLAN............       71
     18.1  Implementation Team..............................       71
     18.2  Implementation Plan..............................       71
     18.3  Action of Implementation Team....................       73
     18.4  Further Coordination and Performance.............       73
     18.5  Operational Review...............................       73
     18.6  Additional Duties of Implementation Team.........       74

ARTICLE XIX
     GENERAL RESPONSIBILITIES OF THE PARTIES................       74
     19.1  Compliance with Implementation Schedule..........       75
     19.2  Compliance with Applicable Law...................       75
     19.3  Necessary Approvals..............................       75
     19.4  Environmental Hazards............................       75
     19.5  Forecasting Requirements.........................       75
     19.6  Certain Network Facilities.......................       76
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     19.7  Traffic Management and Network Harm..............       76
     19.8  Insurance........................................       77
     19.9  Labor Relations..................................       77
     19.10 Good Faith Performance...........................       77
     19.11 Responsibility to Customers......................       77
     19.12 Unnecessary Facilities...........................       77
     19.13 Cooperation......................................       77
     19.14 NXX Code Administration..........................       77
     19.15 LERG Listings....................................       77
     19.16 LERG Use.........................................       78
     19.17 Switch Programming...............................       78
     19.18 Transport Facilities.............................       78

ARTICLE XX
     PROPRIETARY INFORMATION................................       78
     20.1  Definition of Proprietary Information............       78
     20.2  Disclosure and Use...............................       79
     20.3  Government Disclosure............................       81
     20.4  Ownership........................................       81

ARTICLE XXI
     TERM AND TERMINATION...................................       82
     21.1  Term.............................................       82
     21.2  Renegotiation of Certain Terms...................       82
     21.3  Default..........................................       83
     21.4  Transitional Support.............................       83
     21.5  Payment Upon Expiration or Termination...........       83

ARTICLE XXII
     DISCLAIMER OF REPRESENTATIONS AND WARRANTIES...........       83

ARTICLE XXIII
     CANCELLATION CHARGES...................................       84

ARTICLE XXIV
     SEVERABILITY...........................................       84
     24.1  Severability.....................................       84
     24.2  Non-Contravention of Laws........................       84
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ARTICLE XXV                                             
     INDEMNIFICATION........................................       84
     25.1  General Indemnity Rights.........................       84
     25.2  Indemnification Procedures.......................       85

ARTICLE XXVI
     LIMITATION OF LIABILITY................................       86
     26.1  Limited Responsibility...........................       86
     26.2  Apportionment of Fault...........................       86
     26.3  Limitation of Damages............................       86
     26.4  Limitations in Tariffs...........................       87
     26.5  Consequential Damages............................       87
     26.6  Remedies.........................................       87

ARTICLE XXVII
     BILLING................................................       88
     27.1  Billing..........................................       88
     27.2  Recording........................................       88
     27.3  Payment Of Charges...............................       88
     27.4  Late Payment Charges.............................       88
     27.5  Adjustments......................................       89
     27.6  Interest on Unpaid Amounts.......................       89

ARTICLE XXVIII
     AUDIT RIGHTS, DISPUTED AMOUNTS AND DISPUTE RESOLUTION..       89
     28.1  Audit Rights.....................................       89
     28.2  Disputed Amounts.................................       91
     28.3  Dispute Escalation and Resolution................       92
     28.4  Equitable Relief.................................       92

ARTICLE XXIX
     REGULATORY APPROVAL....................................       93
     29.1  Commission.......................................       93
     29.2  Tariffs..........................................       93
     29.3  Amendment or Other Changes to the Act,
                Reservation of Rights.......................       94
     29.4  Regulatory Changes...............................       94
     29.5  Proxy Rates......................................       94
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ARTICLE XXX
       MISCELLANEOUS........................................       94
       30.1  Authorization..................................       94
       30.2  Designation of Affiliate.......................       95
       30.3  Subcontracting.................................       95
       30.4  Independent Contractor.........................       95
       30.5  Force Majeure..................................       95
       30.6  Governing Law..................................       96
       30.7  Taxes..........................................       96
       30.8  Non-Assignment.................................       97
       30.9  Non-Waiver.....................................       97
       30.10 Notices........................................       97
       30.11 Publicity and Use of Trademarks or Service 
                Marks.......................................       98
       30.12 Nonexclusive Dealings..........................       98
       30.13 No Third Party Beneficiaries, Disclaimer of 
                Agency......................................       99
       30.14 No License.....................................       99
       30.15 Survival.......................................       99
       30.16 Scope of Agreement.............................       99
       30.17 Counterparts...................................       99
       30.18 Entire Agreement...............................       99

ARTICLE XXXI
       AMERITECH COLLOCATION................................      100
       31.1  Physical Collocation...........................      100
       31.2  Eligible Equipment.............................      100
       31.3  Transmission Facility Options..................      100
       31.4  Interconnection Points and Cables..............      100
       31.5  Allocation of Collocation Space................      101
       31.6  Subcontractor and Vendor Approval..............      101
       31.7  Delivery of Collocated Space...................      101
       31.8  Pricing........................................      102
       31.9  Billing........................................      102
       31.10 Additional Requirements........................      102
       31.11 Protection of Service and Property.............      103
       31.12 Standards of Performance.......................      104
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                                    -viii-
<PAGE>
 
             INTERCONNECTION AGREEMENT UNDER SECTIONS 251 AND 252
                     OF THE TELECOMMUNICATIONS ACT OF 1996

      This Interconnection Agreement under Sections 251 and 252 of the
Telecommunications Act of 1996 ("AGREEMENT"), is effective as of the 29th day of
January, 1997/2/ (the "EFFECTIVE DATE"), by and between Ameritech Information
              -
Industry Services, a division of Ameritech Services, Inc., a Delaware
corporation with offices at 350 North Orleans, Third Floor, Chicago, Illinois
60654, on behalf of and as agent for Ameritech Michigan (Ameritech Michigan
referred to herein as "AMERITECH") and Focal Communications Corporation of
Michigan, a Delaware corporation, with offices at 200 N. LaSalle Street, Suite
800, Chicago, Illinois 60601 ("FOCAL").

                                   RECITALS

      A.  Ameritech is an Incumbent Local Exchange Carrier as defined by the
Act, authorized to provide certain Telecommunications Services within Michigan.

      B.  Ameritech is engaged in the business of providing, among other things,
local Telephone Exchange Service within Michigan.

      C.  Focal has been granted authority to provide certain local Telephone
Exchange Services within Michigan and is a Local Exchange Carrier as defined by
the Act.

      D.  The Parties desire to Interconnect their telecommunications networks
and facilities to comply with the Act, and exchange traffic so that their
respective residential and business Customers may communicate with each other
over, between and through such networks and facilities.

      E.  The Parties are entering into this Agreement to set forth the
respective obligations of the Parties and the terms and conditions under which
the Parties will Interconnect their networks and facilities and provide to each
other Telecommunications Services as required by the Act as set forth herein.

      NOW, THEREFORE, in consideration of the mutual premises and the covenants
contained herein and other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, Focal and Ameritech hereby agree
as follows.


___________________

/2/   See Footnote 21 on Signature Page.
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                                   ARTICLE I
                         DEFINITIONS AND CONSTRUCTION
                                        
      1.1  STRUCTURE.

This Agreement includes certain Exhibits and Schedules which immediately follow
this Agreement, all of which are hereby incorporated in this Agreement by this
reference and constitute a part of this Agreement.

      1.2  DEFINED TERMS. Capitalized terms used in this Agreement shall have
the respective meanings specified in SCHEDULE 1.2 or as defined elsewhere in
                                     ------------
this Agreement.

      1.3  INTERPRETATION.

           (a)  The definitions in SCHEDULE 1.2 shall apply equally to both the
                                   ------------
                singular and plural forms of the terms defined. Whenever the
                context may require, any pronoun shall include the
                corresponding masculine, feminine and neuter forms. The words
                "INCLUDE," "INCLUDES" AND "INCLUDING" shall be deemed to be
                followed by the phrase "WITHOUT LIMITATION". The words "SHALL"
                and "WILL" are used interchangeably throughout this Agreement
                and the use of either connotes a mandatory requirement. The use
                of one or the other shall not mean a different degree or right
                or obligation for either Party.

           (b)  References herein to Articles, Sections, Exhibits and Schedules
                shall be deemed to be references to Articles and Sections of, 
                and Exhibits and Schedules to, this Agreement unless the context
                shall otherwise require.

           (c)  The headings of the Articles, Sections, Exhibits and Schedules
                are inserted for convenience of reference only and are not
                intended to be a part of or to affect the meaning or
                interpretation of this Agreement.

           (d)  Unless the context shall otherwise require, any reference to any
                agreement, other instrument (including Ameritech, Focal or
                other third party offerings, guides or practices), statute,
                regulation, rule or tariff is to such agreement, instrument,
                statute, regulation, rule or tariff as amended and supplemented
                from time to time (and, in the case of a statute, regulation,
                rule or tariff, to any successor provision).

           (e)  In the event of a conflict between the provisions of this
                Agreement and the Act, the provisions of the Act shall govern.

      1.4  JOINT WORK PRODUCT. This Agreement is the joint work product of the
Parties and has been negotiated by the Parties and their respective counsel and
shall be fairly interpreted in

                                       2
<PAGE>
 
accordance with its terms and, in the event of any ambiguities, no inferences
shall be drawn against either Party.

      1.5  REGIONAL MATTERS.

           (a)  Focal has a regional administrative structure in which its
                central region ("REGION") comprises the states of Illinois,
                Ohio, Indiana, Michigan and Wisconsin, states in which Ameritech
                Michigan and its Affiliates conduct business operations and in
                which Ameritech Michigan and certain of its Affiliates are
                Incumbent Local Exchange Carriers. Ameritech Michigan and Focal
                currently perform, or cause their Affiliates to perform,
                administrative and specialized business operations on a
                centralized basis in the Region.

           (b)  The Parties shall cooperate in the administration and
                performance of this Agreement and any other agreements between
                the Parties and their Affiliates approved under Section 252 of
                the Act relating to the Parties' provision of
                Telecommunications Services in the Region (the "REGIONAL
                INTERCONNECTION AGREEMENTS") so that the following are
                accomplished: 

                (1)  Whenever this Agreement requires a procedure for deployment
                     of the relevant facilities, services and functions,
                     including formation of an Implementation Team and the
                     development of an Implementation Plan, the Parties shall,
                     to the maximum extent practicable in light of local state
                     differences, use a single Implementation Team to develop a
                     single Implementation Plan which will satisfy the
                     requirements of all Regional Interconnection Agreements.
                     Except as necessary to accommodate individual state
                     differences or requirements, meetings of the Implementation
                     Team shall be held in Chicago, Illinois; and

                (2)  The Parties agree that they will use their best efforts to
                     maintain single points of contact and operational
                     interfaces for all Regional Interconnection Agreements.


                                  ARTICLE II
                      GENERAL SERVICE RELATED PROVISIONS

      2.1  INTERCONNECTION ACTIVATION DATE

      Subject to the terms and conditions of this Agreement, Interconnection of
the Parties' facilities and equipment pursuant to ARTICLES III and IV for the
                                                  ------------     --
transmission and routing of Telephone Exchange Service traffic and Exchange
Access traffic, and Interconnection of the Parties' facilities and equipment to
provide Focal access to Ameritech's unbundled Network Elements pursuant to
ARTICLE IX, shall be established on or before the corresponding "INTERCONNECTION
----------

                                       3
<PAGE>
 
ACTIVATION DATE" shown for each LATA and Wire Center set forth on SCHEDULE 2.1.
                                                                  ------------
The Parties shall refine estimated Interconnection Activation Dates and identify
additional Interconnection Activation Dates using the principles set forth in
SECTION 3.4.4. SCHEDULE 2.1 may be revised and supplemented from time to time
-------------  ------------                                                 
upon the mutual agreement of the Parties to reflect the Interconnection of
additional LATAs and Wire Centers by attaching one or more supplementary
schedules to such Schedule.

      2.2  BONA FIDE REQUEST.

      Any request by Focal for certain services, including features,
capabilities, functionality, Network Elements or Combinations that are not
otherwise provided by the terms of this Agreement at the time of such request
shall be made pursuant to the Bona Fide Request process set forth on SCHEDULE
                                                                     --------
2.2.
---

      2.3  TECHNICAL REFERENCES.

      Technical References that describe the practices, procedures and
specifications for certain services (and the applicable interfaces relating
thereto) are listed on SCHEDULE 2.3 (THE "TECHNICAL REFERENCE SCHEDULE") to
                       ------------                                       
assist the Parties in meeting their respective responsibilities hereunder.

      2.4  USE OF SERVICES.

      Subject to the requirements of this Agreement, the Act, the Commission and
the FCC, Focal may, subject to the payment to Ameritech of all applicable
charges, add to, delete from or change a purchased Resale Service or Network
Element in the provision of service to its Customer.

                                  ARTICLE III
                 INTERCONNECTION PURSUANT TO SECTION 251(C)(2)

      3.1  SCOPE.

      ARTICLE III describes the physical architecture for Interconnection of the
      -----------                                                              
Parties' facilities and equipment for the transmission and routing of Telephone
Exchange Service traffic and Exchange Access traffic between the respective
business and residential Customers of the Parties pursuant to Section 251(c)(2) 
of the Act. Interconnection may not be used solely for the purpose of
originating a Party's own interexchange traffic. ARTICLES IV and V prescribe
                                                  -----------     -          
the specific logical trunk groups (and traffic routing parameters) which will be
configured over the physical Interconnections described in this ARTICLE III
                                                                -----------
related to the transmission and routing of Telephone Exchange Service traffic
and Exchange Access traffic, respectively. Other trunk groups, as described in
this Agreement, may be configured using this architecture.

                                       4
<PAGE>
 
      3.2  INTERCONNECTION POINTS AND METHODS.

           3.2.1  In each LATA identified on SCHEDULE 2.1, Focal and Ameritech
                                             ------------                 
shall Interconnect their networks at the correspondingly identified Ameritech
and Focal Wire Centers on SCHEDULE 2.1 for the transmission and routing within
                          ------------
that LATA of Telephone Exchange Service traffic and Exchange Access traffic
pursuant to Section 251(c)(2) of the Act.

           3.2.2  Interconnection in each LATA shall be accomplished at any
technically feasible point within the Parties' networks through either (i)
Collocation in Ameritech's Wire Centers as provided in ARTICLE XII or (ii) any
                                                       -----------           
other Interconnection method to which the Parties may agree in advance of the
applicable Interconnection Activation Date for a given LATA and which is
consistent with the Act, including a Fiber-Meet as provided in SECTION 3.3.
                                                               -----------
Notwithstanding the foregoing, as provided in Section 251(c)(2) of the Act,
Focal, at its option, may request Interconnection of its facilities and
equipment to Ameritech's network at any technically feasible point in
Ameritech's network, including a mid-span meet arrangement at any transmission
rate for a Telecommunications Service that Ameritech offers to itself, its
subsidiaries, its Affiliates or other persons.

           3.2.3  If Focal elects Collocation as an Interconnection method or
elects a network architecture that requires Ameritech to Interconnect with
Focal's facilities via Collocation, Focal agrees to provide to Ameritech
Collocation for purposes of that Interconnection on a nondiscriminatory basis
and on rates, terms and conditions to be negotiated by the Parties under a
separate agreement that are no less favorable than Focal provides to other
similarly situated Telecommunications Carriers.


     A3.2  FOCAL ALTERNATIVE METHODS OF INTERCONNECTION. As an alternative to
           --------------------------------------------                    
Collocation in Ameritech's Wire Center or Fiber Meet as currently provided for
in this Agreement, Focal may interconnect with Ameritech for purposes of
delivering Local Traffic and IntraLATA Toll Traffic originating in Focal's
network for termination on Ameritech's network by using the alternative method
of Interconnection as described below.

           A3.2.1 Under this method of Interconnection, Focal will transport
           Local Traffic and IntraLATA Toll Traffic to Ameritech's Tandem or End
           Offices by using trunks (i.e., DS1's) on existing DS3 access
           facilities between Focal's Central Office Switches and the Ameritech
           Wire Center. Such facilities may be provided by Ameritech, Focal,
           other vendors used by Focal or Ameritech, or a combination thereof.

           A3.2.2 If additional capacity is needed for Interconnection under
           this method, Focal will provision such facilities (i) from Ameritech
           under its access tariff; (ii) from Focal's own facility inventory; or
           (iii) from an alternative access vendor.

                                       5
<PAGE>
 
           A3.2.3  Focal agrees that until such time as may be agreed to by the
           Parties, or ordered by any court, regulatory authority or other
           tribunal of any dispute, Focal will not use the Dedicated Transport
           Network Element (without access via Collocation) for purposes of
           Interconnection pursuant to the method described in this SECTION
                                                                    -------
           A.3.2.
           -----

           A3.2.4 Focal must interconnect with Ameritech at a DS1 Bandwidth.
           Ameritech may allow Interconnection at other bandwidths where
           technically feasible and mutually agreeable at termination charges to
           be agreed upon by the Parties.

     B3.2  AMERITECH ALTERNATIVE METHODS OF INTERCONNECTION.  Ameritech will 
           ------------------------------------------------
Interconnect with Focal for purposes of delivering Local Traffic and IntraLATA 
Toll Traffic originating in Ameritech's network for termination on Focal's 
network by using one of the following methods or such other methods as may be 
agreed upon by the Parties.

           a)      Collocation in the LEC Access Equipment Room in Focal's Wire 
           Centers as described in SECTION B3.2.1 below:
                                   --------------

           b)      Leasing of DS1 facilities from Focal as described in SECTION 
                                                                        ------- 
           B3.2.2 below; or
           ------

           c)      Leasing facilities from third parties collocated in Focal's 
           space.
                
           B3.2.1  Collocation in Focal Wire Center. Under this method of
                   -------------------------------- 
           Interconnection, Ameritech may transport Local Traffic and IntraLATA
           Toll Traffic to the designated Point of Interconnection ("POI") in
           Focal's Wire Centers by using its self-provided facilities which are
           terminated in Ameritech's equipment located in the LEC Access
           Equipment Room/3/ in Focal's Wire Center used to provide total
                          - 
           services access/4/ for Focal or in Focal provided equipment (when
                           - 
           both Focal and Ameritech are located in the same building).

                   B3.2.1.1  Collocation for purposes of this method of
                   Interconnection will be furnished by Focal under the same
                   terms and conditions that it is provided today to Ameritech
                   for total service access terminal equipment. However, since
                   these terms and conditions may vary from Focal Wire Center to
                   Focal Wire Center, Focal agrees that the terms and conditions
                   described in ARTICLE XXXI will apply. Focal agrees to provide
                                ------------
                   such Collocation on a non-


______________________

/3/    The LEC Access Equipment Room is the space Focal furnishes to Ameritech
       pursuant to Section 2.3.3 of Ameritech Tariff F.C.C. No.2.

/4/    Total service access are access services purchased by Focal from 
 -
       Ameritech to provide switched or dedicated access to Focal Customers.

                                       6
<PAGE>
 
                   discriminatory basis in accordance with the requirements of
                   Section 3.2.3 of the Agreement and Section 202(a) of the Act.

                   B3.2.1.2  In order to accommodate this method of
                   Interconnection, Ameritech may utilize existing equipment
                   installed for the purposes of providing total service access
                   for Focal's use or place additional equipment in the space.

                   B3.2.1.3  Ameritech will interconnect with Focal at each
                   Focal Wire Center in the LATA from each Ameritech Wire Center
                   at which Focal elects to interconnect with Ameritech.
                   Therefore, for each Wire Center combination specified in
                   SCHEDULE 2.1, traffic will terminate between the Parties'
                   ------------
                   respective networks. In those LATA's where Focal does not
                   have a Central Office Switch, Focal will designate a facility
                   Point of Presence (POP) in the LATA where Ameritech will
                   interconnect with Focal. Any transport of traffic beyond that
                   POP will be Focal's responsibility and at Focal's cost. If
                   Focal has more than one local switch in the same building,
                   the interconnection POI for all switches may be located in
                   the same physical space.

                   B3.2.1.4  Ameritech must Interconnect with Focal at a DS1
                   bandwidth. Focal may allow Interconnection at other
                   bandwidths where technically feasible and mutually agreeable
                   at termination charges to be agreed upon by the Parties. DS1
                   Collocation Termination charges apply for the use of space
                   provided for terminating Local Traffic and IntraLATA Toll
                   Traffic as specified in Exhibit PS-VII-A. If the facility is
                   terminated to Focal at a DS3 level, Ameritech must purchase
                   28 DS1 Collocation Termination charges and DS3 to DS1
                   multiplexing, from Focal.

           B3.2.2  Leasing Facilities from Focal. Under this method of
                   -----------------------------                    
           Interconnection, Ameritech may transport traffic to the designated
           POI in Focal's Wire Centers by using DS1 facilities furnished by
           Focal. Such facilities may be used by Ameritech solely for purposes
           of delivering Local Traffic and IntraLATA Toll Traffic originating in
           Ameritech's network for termination on Focal's local network. The POI
           will be established pursuant to the requirements of SECTION B3.2.1.3.
                                                               ----------------

                   B3.2.2.1  Leasing of Focal provided facilities may be used by
                   Ameritech as a: i) permanent method of Interconnection, ii)
                   an interim method of Interconnection if Ameritech does not
                   have sufficient capacity on its transport equipment in the
                   LEC Access space in Focal's Wire Center as described in
                   SECTION B3.2.3 or iii) in conjunction with Collocation as
                   --------------
                   described in SECTION B3.2.4.
                                --------------

                   B3.2.2.2  If Ameritech requests to lease Focal provided
                   facilities, Focal will determine the availability of DS1
                   transport capacity between Ameritech and

                                       7
<PAGE>
 
                   Focal in order to fulfill the Interconnection access request.
                   If capacity is available, Focal will notify Ameritech and
                   provide Connecting Facility Assignments (CFA). If DS1 
                   capacity is not available from Focal provided facilities,
                   Focal will notify Ameritech that Focal will not fulfill the
                   Interconnection access request. Focal will have no obligation
                   to add facilities to meet Ameritech's request.

                   B3.2.2.3  If Ameritech leases facilities from Focal, such
                   facilities will be provided pursuant to Focal's standard
                   terms and conditions for that service, except that the rates
                   specified in Exhibit PS-VII-A shall supersede the
                   corresponding rates in such standard terms and conditions.

                   B3.2.2.4  The standard interval for Focal provided
                   facilities is thirty-three (33) Business Days from the date
                   of receipt of Ameritech's ASR. However, the initial request
                   for Interconnection at an Focal Wire Center will be regarded
                   as a project and therefore require negotiated intervals on
                   an individual case basis.

            B3.2.3  Interim Leasing.  Focal will provide Ameritech a minimum of
                    ---------------                                         
            ninety (90) calendar days prior notification of its intention to
            begin accepting incoming traffic from Ameritech. If Ameritech elects
            to interconnect with Focal using the method described in SECTION
                                                                     -------
            B3.2.1 and does not have sufficient capacity on its transport
            ------
            equipment in the LEC Access space in Focal's Wire Center to meet the
            Interconnection traffic requirements, at either Party's request,
            Ameritech will use facilities leased from Focal.

                   B3.2.3.1  Interim facilities will be provided by Focal
                   pursuant to the requirements of SECTION B3.2.2, subject to
                                                   --------------
                   the following:

                         B3.2.3.1.1  If Ameritech is required to use Focal
                         provided DS1 facilities for an interim period,
                         Ameritech will pay Focal the nonrecurring charge and
                         the monthly recurring charge for these facilities,
                         subject to the discount described below.

                         B3.2.3.1.2  No discounts shall apply if the additional
                         equipment which Ameritech must install can be added to
                         existing bays in the space.

                         B3.2.3.1.3  If Ameritech requires the addition of a new
                         bay to complete Interconnection by Collocation, and
                         Focal gives Ameritech less than ninety (90) calendar
                         days advance notice of its intention to accept incoming
                         traffic, the DS1 rate will be reduced by 1/60 of the
                         monthly recurring, charge for each day less than such
                         ninety (90) calendar days of the notification of intent
                         to accept incoming traffic. The discounted rate will
                         only be applicable for a period of no longer

                                       8
<PAGE>
 
                         than 150 calendar days from the date Focal informed
                         Ameritech of its intention to accept incoming traffic.
                         At the 151st calendar day, the discounts will no
                         longer apply. Ameritech has the option to use these
                         facilities as a permanent method of Interconnection or
                         to transition to physical Collocation as a method of
                         Interconnection. If Ameritech opts to transition to
                         physical Collocation facilities, Focal will waive
                         additional non-recurring charges. If Ameritech elects
                         to keep leased facilities as a permanent method of
                         Interconnection, Focal will bill Ameritech for and
                         Ameritech will repay the discounts that had been
                         applied in the interim period.

           B3.2.4  Leasing in Conjunction with Physical Collocation. Ameritech
                   ------------------------------------------------
           may elect to combine Interconnection by Collocation as described in
           SECTION B3.2.1 with leasing facilities from Focal as described in
           -------------- 
           SECTION B3.2.2 by using the leased facilities to connect from an
           --------------
           intermediate point on the Focal network at which Ameritech is
           Collocated to the Focal Wire Center at which the designated POI is
           located. For example, the Focal End Office is Office A and Focal
           facility office is Office B. Ameritech may have capacity to terminate
           a facility at Focal Office B, but decides to lease a facility from
           Focal to get to the End Office A. In this scenario, both DS1 facility
           charges and charges for Focal space would apply.

           B3.2.5  Interconnection in Other ILEC Territories. In those instances
                   -----------------------------------------                  
           where Focal's POI is in an ILEC territory other than Ameritech's in
           a multi-jurisdictional LATA, Ameritech may interconnect using such
           other ILEC facilities for transporting Local Traffic and IntraLATA
           Toll Traffic to the designated POI in Focal's Wire Centers by using
           ILEC provided facilities which are terminated in ILEC's equipment
           located in the LEC Access Equipment Room in Focal's Wire Center used
           to provide total service access/5/ for Focal or in Focal provided
           equipment (when both Focal and the ILEC are located in the same
           building) on the same terms and conditions as specified in B.3.2.1.
                                                                      -------

           B3.2.6  Leasing Facilities From Third Parties.  In the future,
                   --------------------------------------              
           Ameritech may utilize Alternate Access Providers which are collocated
           in Focal Wire Centers to lease facilities for interconnecting with
           Focal for the termination of Ameritech's Local Traffic and IntraLATA
           Toll Traffic. Upon notification from Ameritech of its intent to
           utilize Alternate Access Provider facilities, Focal will provide
           applicable pricing to be agreed upon by the Parties.
                     

     C3.2  SS7 INTERCONNECTION.
           -------------------

____________________

/5/  Total service access are access services purchased by Focal from ILEC to
 -                                                                          
     provide switched or dedicated access to Focal Customers.

                                       9
<PAGE>
 
          C.3.2.1  Ameritech's Use of Focal Network. Focal's process for billing
                   --------------------------------                           
          Signaling Facility, Port and Message Usage is outlined below. For
          Common Channel Signaling (CCS) network usage dedicated to network
          Interconnection, Focal will apply its tariffed monthly recurring and
          non-recurring rates for Ports and Links used by Ameritech as well as a
          per message CCS call set-up charge. In the case of CCS network usage
          shared for exchange access and network interconnection purposes, Focal
          has developed a process for calculating a Percent Local Signaling 
          factor. In the course of exchanging traffic with Focal, Ameritech will
          utilize the Focal CCS network. This procedure will enable Focal to
          calculate a factor that will be applied to its tariffed recurring and
          non-recurring rates for Signaling Ports and Links, as well as to
          measure and apply a rate per CCS call set up message. Focal will bill
          Ameritech both pro-rated link facility and port charges based on a
          percentage factor and a per signaling message charge applied to each
          inbound call attempt. This usage bill will be based on Initial 
          Address Messages (IAM). Transaction Capabilities Application Part
          (TCAP) messages are not part of Focal's current service offering. If
          in the future Focal requires TCAP messages to be exchanged, the
          Parties will negotiate appropriate rates.

                   C.3.2.1.1  Signaling Facility and Port Billing Criteria for
                              -----------------------------------------------
                   Shared CCS Network Usage
                   ------------------------

                   Focal will initiate and maintain a process that will poll its
                   end offices switches to develop an aggregate collection of
                   inbound call attempts received from Ameritech. This number
                   will be used as a numerator in a formula to calculate a usage
                   percentage. Focal will also aggregate total originating and
                   terminating call attempts traversing all trunk groups between
                   Ameritech and Focal's end office switches. This number will
                   serve as the denominator. The percentage derived from this
                   process will be applied as a factor against Focal's tariffed
                   recurring and non-recurring rates for Signaling Links and
                   Ports.

                   TOTAL # CALL ATTEMPTS INBOUND LOCAL TRUNKS = % FACTOR
                   ------------------------------------------
                   TOTAL # IN & OUT CALL ATTEMPTS ON ALL TRUNKS

                   % FACTOR X FACILITY & PORT RATE = FIXED BILL

                   C3.2.1.2  Signaling Message Usage Billing
                             -------------------------------

                   Focal will also apply a per signaling message rate to the
                   total number of inbound call attempts as aggregated and
                   described above. This rate will represent the total number of
                   IAMs that are involved in the call set up process. See
                   example

                                       10
<PAGE>
 
                   TOTAL # CALL ATTEMPTS X IAM PER MESSAGE =USAGE BILL INBOUND 
                   LOCAL TRUNKS RATE

                   C3.2.1.3  Credits and Debits
                             ------------------ 

                   The percentage factor will be applied against Focal's
                   Signaling Facility and Port rates to create a prorated bill
                   that will be rendered to Ameritech for payment. Additionally,
                   Focal will include the per message usage total in the bill
                   rendered to Ameritech.

           C3.2.2  Focal's Use of Ameritech's Signaling.  For Common Channel
                   ------------------------------------
           Signaling (CCS) network usage dedicated to network interconnection,
           Focal will pay Ameritech on the same basis as it pays Ameritech for
           signaling associated with switched access until such time as (i)
           Ameritech implements a method to measure CCS usage associated with
           local traffic; or (ii) the Parties agree otherwise, or are ordered by
           any court, regulatory authority or other tribunal.

           C3.2.3  Each Party will bill in accordance with the methodology
           described above. However, neither Party agrees with the methodology
           described above for calculating and charging for signaling usage of
           the other Party. Therefore, a Party may challenge the methodology
           described above in accordance with the dispute resolution procedure
           of SECTION 28.3 and challenge the billing in accordance with its
              ------------                 
           rights under SECTION 28.2. If a different methodology is ordered by a
                        ------------      
           court, regulatory authority or other tribunal of such dispute,
           charges will be trued-up in accordance with the methodology for
           charging for CCS usage approved in such proceeding.

      3.3  FIBER-MEET.

           3.3.1   If the Parties Interconnect their networks pursuant to a
Fiber-Meet, the Parties shall jointly engineer and operate a single Synchronous
Optical Network ("SONET") transmission system. Unless otherwise mutually agreed,
this SONET transmission system shall be configured as illustrated in EXHIBIT A,
                                                                     ---------
and engineered, installed, and maintained as described in this ARTICLE III and
                                                               -----------
in the Plan (as defined in SECTION 8.1).
                           -----------

           3.3.2   Ameritech shall, wholly at its own expense, procure, install
and maintain Optical Line Terminating Multiplexor ("OLTM") equipment in the
Ameritech Interconnection Wire Center ("AIWC") identified for each LATA set
forth on SCHEDULE II.1, in capacity sufficient to provision and maintain all
         -------------                                                    
logical trunk groups prescribed by ARTICLES IV and V.
                                   -----------     -

           3.3.3   Focal shall, wholly at its own expense, procure, install and
maintain the OLTM equipment in the Focal Interconnection Wire Center ("FIWC")
identified for that LATA in SCHEDULE II.1, in capacity sufficient to provision
                            -------------                                   
and maintain all logical trunk groups prescribed by ARTICLES IV and V.
                                                    -----------     -

                                       11
<PAGE>
 
           3.4.3   Unless otherwise agreed by the Parties, the Parties shall
designate the Wire Center Focal has identified as its initial Routing Point in
the LATA as the FIWC in that LATA and shall designate the Ameritech Tandem
Office Wire Center within the LATA nearest to the FIWC (as measured in airline
miles utilizing the V&H coordinates method) as the AIWC in that LATA.

           3.4.4   The Interconnection Activation Date in each new LATA shall be
mutually established based on then-existing force and load, the scope and
complexity of the requested Interconnection and other relevant factors. The
Parties acknowledge that, as of the Effective Date, the average interval to
establish Interconnection via Collocation or Fiber-Meet is one hundred fifty
(150) days. Within ten (10) Business Days of Ameritech's receipt of Focal's
notice specified in SECTION 3.4.1, Ameritech and Focal shall confirm the AIWCs,
                    -------------                                           
the FIWCs and the Interconnection Activation Date for the new LATA by attaching
a supplementary schedule to SCHEDULE 2.1.
                            -------------

      3.5  ADDITIONAL INTERCONNECTION IN EXISTING LATAs.  If Focal deploys
additional switches in a LATA after the Effective Date, or otherwise wishes to
establish Interconnection with additional Ameritech Central Offices, Focal shall
be entitled, upon written notice thereof to Ameritech, to establish such
Interconnection and the terms and conditions of this Agreement shall apply to
such Interconnection. If Ameritech deploys additional switches in a LATA after
the Effective Date, or otherwise wishes to establish Interconnection with
additional Focal Central Offices, Ameritech shall be entitled, upon written
notice thereof to Focal, to establish such Interconnection and the terms and
conditions of this Agreement shall apply to such Interconnection. If either
Party establishes an additional Tandem Switch in a given LATA, the Parties shall
jointly determine the requirements regarding the establishment and maintenance
of separate trunk group connections and the sub-tending arrangements relating to
Tandem Switches and End Offices which serve the other Party's Customers within
the Exchange Areas served by such Tandem Switches.

      3.6  NONDISCRIMINATORY INTERCONNECTION. Interconnection shall be equal in
quality to that provided by the Parties to themselves or any subsidiary,
Affiliate or other person. For purposes of this SECTION 3.6, "EQUAL IN quality" 
                                                -----------      
means the same technical criteria and service standards that a Party uses within
its own network. If Focal requests an Interconnection that is of a different
quality than that provided by Ameritech to itself or any subsidiary, Affiliate
or other person, such request shall be treated as a Bona Fide Request and
established upon rates, terms and conditions consistent with the Act.

      3.7  NETWORK MANAGEMENT.

           3.7.1   Focal and Ameritech shall work cooperatively to install and
maintain a reliable network. Focal and Ameritech shall exchange appropriate
information (e.g., maintenance contact numbers, network information, information
             ----  
required to comply with law enforcement and other security agencies of the
government and such other information as the Parties shall mutually agree) to
achieve this desired reliability.

                                      13
<PAGE>
 
           3.7.2   Focal and Ameritech shall work cooperatively to apply sound
network management principles by invoking network management controls to
alleviate or to prevent congestion.

      3.8  STANDARDS OF PERFORMANCE.

           3.8.1   Each Party shall provide the other Party Interconnection (i)
in accordance with SECTION 3.6 as determined by this SECTION 3.8 and (ii) as
                   -----------                       -----------           
required by the Commission (collectively, the "INTERCONNECTION PERFORMANCE
BENCHMARKS").

           3.8.2   To determine a Party's compliance with the Interconnection
Performance Benchmarks, each Party shall maintain separate records of the
specific criteria listed on SCHEDULE 3.8 (each, an "INTERCONNECTION PERFORMANCE
                            ------------                                      
ACTIVITY") relating to Interconnection that it provides to itself, its
subsidiaries, and Affiliates (the "PROVIDING PARTY'S INTERCONNECTION RECORDS")
and to other LECs (the "OTHER LEC INTERCONNECTION RECORDS") and parallel
records of the Interconnection that the Providing Party provides to the other
Party (the "OTHER PARTY'S INTERCONNECTION RECORDS") and shall use the methods
described in SCHEDULE 3.8 to calculate Interconnection Performance Activity and
             ------------                                                
determine compliance with such Interconnection Performance Activity and with
such additional criteria to which the Parties may agree upon, including those
regarding Ameritech's compliance with different performance levels and intervals
requested by Focal and provided by Ameritech pursuant to SECTION 3.6 and a Bona
                                                         -----------
Fide Request.

           3.8.3   The Providing Party shall provide to the other Party for each
calendar month (a "REPORTING PERIOD"), by the twenty-second (22nd) day of the
following month, in a self-reporting format, the Providing Party's 
Interconnection Records, the Other LEC Interconnection Records and the Other 
Party's Interconnection Records so that the Parties can determine the Providing
Party's compliance with the Interconnection Performance Benchmarks If (i) the
Providing Party fails to comply with an Interconnection Performance Benchmark
with respect to an Interconnection Performance Activity for a Reporting Period.
(ii) the sample size of the Interconnection Performance Activity measured for
such Reporting Period is statistically valid and (iii) the amount by which the
applicable Interconnection Performance Activity deviates from the corresponding
Interconnection Performance Benchmark is statistically significant, then the
Providing Party shall have committed a "Specified Performance Breach".
Notwithstanding anything to the contrary in this SECTION 3.8, the Parties
                                                 ----------- 
acknowledge that (x) the Providing Party shall not be required to provide to the
other Party those Other LEC Interconnection Records that correspond to and
measure levels of quality and performance levels and intervals of
Interconnection that are requested by an Other LEC pursuant to 47 C.F.R. (S)5
1.305(a)(4); (y) the Other LEC Interconnection Records shall be provided to the
other Party on an aggregate basis and (z) such Other LEC Interconnection Records
shall be provided to the other Party in a manner that preserves the
confidentiality of each other LEC and any of such LEC's proprietary information
(including CPNI).

           3.8.4   In no event shall the Providing Party be deemed to have
committed a Specified Performance Breach if the Providing Party's failure to
meet or exceed an Interconnection Performance Activity is caused by a Delaying 
Event. If a Delaying Event (i) prevents the Providing

                                      14
<PAGE>
 
Party from performing a certain function or action that affects an
Interconnection Performance Activity, then such occurrence shall be excluded
from the calculation of such Interconnection Performance Activity and the
determination of the Providing Party's compliance with the applicable
Interconnection Performance Benchmark or (ii) only suspends the Providing
Party's ability to timely perform such Interconnection Performance Activity,
then the applicable time frame in which the Providing Party's compliance with
the Interconnection Performance Benchmark is measured shall be extended on a
like-time basis equal to the duration of such Delaying Event.

           3.8.5   Upon the occurrence of a Specified Performance Breach by the
Providing Party, the other Party may forego the dispute escalation procedures
set forth in SECTION 28.3 and (i) bring an action against the Providing Party in
             ------------                                                      
an appropriate Federal district court, (ii) file a complaint with the FCC
pursuant to Sections 207 or 208 of the Act, (iii) seek a declaratory ruling from
the FCC, (iv) file a complaint in accordance with the rules, guidelines and
regulations of the Commission or (v) seek other relief under Applicable Law.

           3.8.6   The other Party shall also be entitled to any Credit
Allowances pursuant to the same terms and conditions that the Providing Party
offers Credit Allowances to its Customers, including those described on SCHEDULE
                                                                        --------
10.9.6.
------

           3.8.7   The Parties' agreement to the procedures set forth in this
SECTION 3.8 shall not (i) relieve either Party of its obligations to perform
-----------                                          
any other duties under this Agreement or (ii) constitute a waiver of a right of
either Party to claim that the parity requirements of this Agreement and of the
Act have or have not been met.

3.9  9-1-1 SERVICE.

           3.9.1   Ameritech shall provide 9-1-1 Service to Focal as described
in this SECTION 3.9 in each Rate Center in which (i) Focal is authorized to
        -----------                                                       
provide local exchange services and (ii) Ameritech is the 9-1-1 service
provider.

           3.9.2   Service and Facilities Provided. 

           (a)     Ameritech will provide Focal with multiplexing at a
                   designated Ameritech Central Office at the rates set forth at
                   Item I of the Pricing Schedule and pursuant to the terms and
                   conditions in applicable tariffs. Ameritech will also provide
                   Focal with trunking from the Ameritech Central Office to the
                   designated Ameritech Control Office(s) with sufficient
                   capacity to route Focal's originating 9-1-1 calls over
                   Service Lines to the designated primary PSAP or to designated
                   alternate locations. Such trunking will be provided at the
                   rates set forth at Item I of the Pricing Schedule. If Focal
                   forwards the ANI information of the calling party to the
                   Control Office, Ameritech will forward that calling number
                   and the associated street address to the PSAP for display. If
                   no ANI is forwarded by Focal, Ameritech will display a
                   Central Office identification code for display at the PSAP.

                                      15
<PAGE>
 
           (b)     Focal will provide the necessary trunking to route
                   originating 9-1-1 traffic from Focal's End Office(s) to the
                   Ameritech Control Office(s). The points of Interconnection
                   for primary and diverse routes are identified at SECTION 2 of
                                                                    ---------
                   SCHEDULE 3.9. Focal may, at its option, acquire such
                   ------------
                   trunking from Ameritech at rates, terms and conditions
                   provided in Ameritech's tariffs.

           (c)     Ameritech will provide to Focal, in paper or mechanized
                   format, an address and routing file that will specify which
                   9-1-1 Control Office serves as the jurisdictional 9-1-1
                   answering point for Customers within the Exchange Areas
                   served by Focal. The address and routing file will be
                   provided by exchange rate center or community upon request. A
                   specified charge as set forth at Item I of the Pricing 
                   Schedule will apply per request. Until such time as a
                   mechanized process for provision of this information is made
                   available by Ameritech and, at intervals determined by
                   Ameritech, Ameritech shall provide to Focal in a paper format
                   any updates to the address and routing file.

           (d)     Ameritech will coordinate access to the Ameritech ALI
                   database for the initial loading and updating of Focal
                   Customer information. Access coordination will include:

                   (1)   Ameritech provided format requirements and a delivery
                         address for Focal to supply an electronic version of
                         Customer telephone numbers, addresses and other
                         information both for the initial load and, where
                         applicable, daily updates. Ameritech shall confirm
                         receipt of this data as described in SECTION
                                                              -------    
                         III.9.2(h);
                         ----------

                   (2)   Coordination of error resolution involving entry and
                         update activity;

                   (3)   Provisioning of specific 9-1-1 routing information on
                         each access line;

                   (4)   Updating the Ameritech ALI database from paper records
                         of service order activity supplied by Focal is
                         optional. The charge for this service is separate and
                         set forth at Item I of the Pricing Schedule under the
                         category "Optional Manual Update"; and

                   (5)   Providing Focal with reference data required to ensure
                         that Focal's Customer will be routed to the correct
                         Control Office when originating a 9-1-1 call.

           (e)     Focal shall pay Ameritech a one-time charge as set forth at
                   Item I of the Pricing Schedule per 9-1-1 Control Office
                   trunk group (the "9-1-1 CONTROL OFFICE SOFTWARE ENHANCEMENT
                   CONNECTION CHARGE"). Although the services offered in this
                   Agreement and the charges set forth at Item I of the

                                      16
<PAGE>
 
                   Pricing Schedule contemplate that each NXX will reside in a
                   single Control Office, Focal may, at its sole option, 
                   designate that an NXX shall reside in more than one 9-1-1 
                   Control Office.
 
          (f)     In the event of an Ameritech or Focal 9-1-1 trunk group
                   failure, the Party that owns the trunk group will notify, on
                   a priority basis, the other Party of such failure, which
                   notification shall occur within two (2) hours of the
                   occurrence or sooner if required under Applicable Law. The
                   Parties will exchange a list containing the names and
                   telephone numbers of the support center personnel responsible
                   for maintaining the 9-1-1 Service between the Parties.

           (g)     Ameritech will provide the order number and circuit
                   identification code in advance of the service due date.

           (h)     Focal or its third party agent will provide CNA data to
                   Ameritech for use in entering the data into the 9-1-1
                   database. The initial CNA data will be provided to Ameritech
                   in a format prescribed by Ameritech. Focal is responsible for
                   providing Ameritech updates to the CNA data and error
                   corrections which may occur during the entry of CNA data to
                   the Ameritech 9-1-1 Database System. Focal shall reimburse
                   Ameritech for any additional database charges incurred by
                   Ameritech for errors in CNA data updates caused by Focal or
                   its third party agent. Ameritech will confirm receipt of
                   such data and corrections by the next Business Day by 
                   providing Focal with a report of the number of items sent, 
                   the number of items entered correctly, and the number of
                   errors.

           (i)     Focal will monitor the 9-1-1 circuits for the purpose of
                   determining originating network traffic volumes. Focal will
                   notify Ameritech if the traffic study information indicates
                   that additional circuits are required to meet the current
                   level of 9-1-1 call volumes.

           (j)     Incoming trunks for 9-1-1 shall be engineered to assure
                   minimum P.01 grade of service as measured using the "busy
                   day/busy hour" criteria.

           3.9.3   Compensation.

           In addition to the amounts specified in SECTION III.9.2, Focal shall
                                                   ---------------
compensate Ameritech as set forth at Item I of the Pricing Schedule.

           3.9.4   Additional Limitations of Liability Applicable to 9-1-1
Service.

           (a)     Ameritech is not liable for the accuracy and content of CNA
                   data that Focal delivers to Ameritech. Focal is responsible
                   for maintaining the accuracy and content of that data as
                   delivered.

                                      17
<PAGE>
 
           (b)     Notwithstanding anything to the contrary contained herein,
                   Ameritech's liability to Focal and any third person shall be
                   limited to the maximum extent permitted by Mich. Comp. Laws
                   Section 484.1604.

                                  ARTICLE IV
                TRANSMISSION AND ROUTING OF TELEPHONE EXCHANGE
                 SERVICE TRAFFIC PURSUANT TO SECTION 251(c)(2)
                                        
      4.1  SCOPE OF TRAFFIC.  ARTICLE IV prescribes parameters for trunk groups
                              ----------                                        
(the "LOCAL/INTRALATA TRUNKS") to be effected over the Interconnections
specified in ARTICLE III for the transmission and routing of Local Traffic and
             -----------
IntraLATA Toll Traffic between the Parties' respective Telephone Exchange
Service Customers.

      4.2  LIMITATIONS. No Party shall terminate Exchange Access traffic or
originate untranslated 800/888 traffic over Local/IntraLATA Interconnection
Trunks.

      4.3  TRUNK GROUP ARCHITECTURE AND TRAFFIC ROUTING.

The Parties shall jointly engineer and configure Local/IntraLATA Trunks over
the physical Interconnection arrangements as follows:

           4.3.1   Each Party shall initially configure either a one (1)-or a
two (2)-way trunk group as a direct transmission path between each FIWC and
AIWC.

           4.3.2   Notwithstanding anything to the contrary contained in this
ARTICLE IV, if the traffic volumes between any two (2) Central Office Switches 
----------
at any time exceeds the CCS busy hour equivalent of one (1) DS1, the Parties
shall, within sixty (60) days after such occurrence, establish new direct trunk
groups to the applicable End Office(s) consistent with the grades of service and
quality parameters set forth in the Plan.

           4.3.3   Only those valid NXX codes served by an End Office may be
accessed through a direct connection to that End Office.

           4.3.4   Each Party shall ensure that each Tandem connection permits
the completion of traffic to all End Offices which sub-tend that Tandem.
Pursuant to ARTICLE V, each Party shall establish and maintain separate trunk
            ---------
groups connected to each Tandem of the other Party which serves, or is sub-
tended by End Offices which serve, such other Party's Customers within the
Exchange Areas served by such Tandem Switches.

           4.3.5   Each Party shall, upon request of the other Party, provision,
within thirty (30) days of such request, additional trunks for use in a pre-
existing Interconnection arrangement, subject to SECTION 19.12. of this
                                                 -------------       
Agreement.

                                      18
<PAGE>
 
      4.4  SIGNALING.

Signaling Interconnection may be used for signaling between Focal switches,
between Focal switches and Ameritech switches, and between Focal switches and
those third party networks with which Ameritech's SS7 network is interconnected.

           4.4.1   Where available, Common Channel Interoffice Signaling (CCIS)
signaling shall be used by the Parties to set up calls between the Parties'
Telephone Exchange Service networks. Each Party shall supply Calling Party
Number (CPN) within the SS7 signaling message, if available. If CCIS is
unavailable, Multi-Frequency (MF) signaling shall be used by the Parties. Each
Party shall charge the other Party equal and reciprocal rates for CCIS signaling
at the rates set forth at Item V of the Pricing Schedule.

           4.4.2   Each Party is responsible for requesting Interconnection to
the other Party's CCIS network, where SS7 signaling on the trunk group(s) is
desired. Each Party shall connect to a pair of access STPs that serve each LATA
where traffic will be exchanged or shall arrange for signaling connectivity
through a third party provider which is connected to the other Party's signaling
network. The Parties shall establish Interconnection at the STP.

           4.4.3   The Parties will cooperate on the exchange of Transactional
Capabilities Application Part (TCAP) messages to facilitate interoperability of
CCIS-based features between their respective networks, including all CLASS
features and functions, to the extent each Party offers such features and
functions to its Customers. All CCIS signaling parameters will be provided,
including Calling Party Number (CPN), Originating Line Information (OLI),
calling party category and charge number. For terminating Exchange Access
traffic, such information shall be passed by a Party to the extent that such
information is provided to such Party.

           4.4.4   Where available and upon the request of the other Party, each
Party shall cooperate to ensure that its trunk groups are configured utilizing
the B8ZS ESF protocol for 64 Kbps clear channel transmission to allow for ISDN
interoperability between the Parties' respective networks.

      4.5  GRADES OF SERVICE.

The Parties shall initially engineer and shall jointly monitor and enhance all
trunk groups consistent with the Plan.

      4.6  MEASUREMENT AND BILLING.

           4.6.1   For billing purposes, each Party shall pass Calling Party
Number (CPN) information on each call that it originates over the
Local/IntraLATA Trunks; provided that all calls exchanged without CPN 
                        --------    
information shall be billed as either Local Traffic or IntraLATA Toll Traffic
based upon a percentage of local usage (PLU) factor calculated based on the
amount of actual volume during the preceding three (3) months. The PLU will be
reevaluated every three (3)

                                      19
<PAGE>
 
months. If either Party fails to pass at least ninety percent (90%) of calls
with CPN that it originates within a monthly billing period, then either Party
may require that separate trunk groups for Local Traffic and IntraLATA Toll
Traffic be established.

           4.6.2   Measurement of Telecommunications traffic billed hereunder
shall be (i) in actual conversation time as specified in FCC terminating FGD
Switched access tariffs for Local Traffic and (ii) in accordance with applicable
tariffs for all other types of Telecommunications traffic.

           4.6.3   On an interim basis, until such time as the Parties may
agree otherwise, or ordered by any court, regulatory authority or other
tribunal of any dispute, for the method of Interconnection described in SECTION
                                                                        -------
A.3.2, Focal will route IntraLATA Toll Traffic and Local Traffic associated with
-----
an Ameritech-assigned Calling Party Number (CPN) and originating with Focal and
terminating with a Local Exchange Carrier other than Ameritech through Focal's
switched access trunks and will pay applicable access charges for such traffic
until such time that either (a) Focal is able to deliver a Calling Party Number
associated with an Focal LERG assigned number, or (b) the Customer's telephone
number has been ported to Focal using either Interim or Permanent Number
Portability. In the latter case, Focal shall provide to Ameritech at least
thirty 30 days' prior written notice of its intent to reroute this traffic over
the Interconnection trunks. Focal's agreement to route transit traffic as
described above shall not preclude Focal from asserting a contrary position
before any court, regulatory authority or other tribunal of any dispute.

      4.7  RECIPROCAL COMPENSATION ARRANGEMENTS -- SECTION 251(B)(5).

           4.7.1   Reciprocal Compensation applies for transport and termination
of Local Traffic billable by Ameritech or Focal which a Telephone Exchange
Service Customer originates on Ameritech's or Focal's network for termination on
the other Party's network./6/ The Parties shall compensate each other for such
                           -
transport and termination of Local Traffic at the rate provided at Item II of
the Pricing Schedule.

           4.7.2   The Reciprocal Compensation arrangements set forth in this
Agreement are not applicable to Switched Exchange Access Service. All Switched
Exchange Access Service and all IntraLATA Toll Traffic shall continue to be
governed by the terms and conditions of the applicable federal and state
tariffs.


________________________

/6/   Ameritech maintains that it was not Ameritech's intention in entering into
 -
      the Teligent Agreement, the AT&T Agreement or this Agreement that the
      Parties pay each other Reciprocal Compensation for traffic routed through
      or to Internet Service Providers (including, internet traffic). However,
      it is Focal's position that the Teligent Agreement and AT&T Agreement
      required the Parties to pay each other Reciprocal compensation for traffic
      routed through or to Internet Services Providers (including, internet
      traffic) and, by virtue of Focal's adoption of the Teligent Agreement
      under Section 252(i) of the Act, the same obligation applies under this
      Agreement.

                                      20
<PAGE>
 
           4.7.3   Each Party shall charge the other Party its effective
applicable federal and state tariffed intraLATA FGD switched access rates for
the transport and termination of all IntraLATA Toll Traffic.

           4.7.4   Compensation for transport and termination of all traffic
which has been subject to performance of INP by one Party for the other Party
pursuant to ARTICLE XIII shall be as specified in SECTION 13.7.
            ------------                          ------------

                                   ARTICLE V
                     TRANSMISSION AND ROUTING OF EXCHANGE
                     ACCESS TRAFFIC PURSUANT TO 251(C)(2)
                                        
      5.1  SCOPE OF TRAFFIC.  ARTICLE V prescribes parameters for certain trunk
                              --------                                        
groups ("ACCESS TOLL CONNECTING TRUNKS") to be established over the
Interconnections specified in ARTICLE III for the transmission and routing of
                              -----------                                    
Exchange Access traffic and nontranslated 800 traffic between Focal Telephone
Exchange Service Customers and Interexchange Carriers. Compensation for such
Exchange Access traffic is provided for in ARTICLE VI.
                                           ----------

      5.2  TRUNK GROUP ARCHITECTURE AND TRAFFIC ROUTING.

           5.2.1   The Parties shall jointly establish Access Toll Connecting
Trunks by which they will jointly provide Tandem-transported Switched Exchange
Access Services to Interexchange Carriers to enable such Interexchange Carriers
to originate and terminate traffic from and to Focal's Customers.

           5.2.2   Access Toll Connecting Trunks shall be used solely for the
transmission and routing of Exchange Access and nontranslated 800/888 traffic
to allow Focal's Customers to connect to or be connected to the interexchange
trunks of any Interexchange Carrier which is connected to an Ameritech access
Tandem.

           5.2.3   The Access Toll Connecting Trunks shall be two-way trunks
connecting an End Office Switch that Focal utilizes to provide Telephone
Exchange Service and Switched Exchange Access Service in a given LATA to an
access Tandem Switch Ameritech utilizes to provide Exchange Access in such LATA.

           5.2.4   In each LATA identified on SCHEDULE 2.1, each Focal End
                                              ------------
Office Switch in that LATA shall subtend each Ameritech access Tandem in that 
LATA.

           5.2.5   Only those valid NXX codes served by an End Office may be
accessed through a direct connection to that End Office.

                                      21
<PAGE>
 
                                  ARTICLE VI
                        MEET-POINT BILLING ARRANGEMENTS
                                        
      6.1  MEET-POINT BILLING SERVICES.

           6.1.1  Pursuant to the procedures described in Multiple Exchange
Carrier Access Billing ("MECAB") document SR-BDS-000983, issue 5, June 1994,
the Parties shall provide to each other the Switched Access Detail Usage Data
and the Switched Access Summary Usage Data to bill for jointly provided switched
access service such as switched access Feature Groups B and D. The Parties agree
to provide this data to each other at no charge. If the procedures in the
MECAB document are amended or modified, the Parties shall implement such amended
or modified procedures within a reasonable period of time.

           6.1.2  Focal shall designate access Tandems or any other reasonable
facilities or points of Interconnection for the purpose of originating or
terminating IXC traffic. For each such access Tandem designated, the Parties
shall mutually agree upon a billing percentage as set forth on SCHEDULE 6.0 and
                                                               ------------  
shall further agree, within thirty (30) days of the Effective Date, /7/ upon
                                                                     -
billing percentages for additional routes, which billing percentages shall
be set forth in SCHEDULE 6.0 as amendments hereto. Either Party may make this
                ------------                                                    
billing percentage information available to IXCs. The billing percentages shall
be calculated according to one of the methodologies specified for such purposes
in the MECAB document.

           6.1.3  The Parties shall undertake all reasonable measures to ensure
that the billing percentage and associated information are maintained in
their respective federal and state access tariffs, as required, until such time
as such information can be included in the National Exchange Association
("NECA") FCC Tariff No. 4. Focal shall use its best efforts to include in such
tariff the billing percentage and associated information as a non-member of
NECA.

           6.1.4  Each Party shall implement the "MULTIPLE BILL/SINGLE TARIFF"
option in order to bill the IXC for each Party's own portion of jointly provided
Telecommunications Service.

      6.2  DATA FORMAT AND DATA TRANSFER.

           6.2.1  Necessary billing information will be exchanged on magnetic
tape or via electronic data transfer (when available) using the EMR format. The
Parties shall agree to a fixed billing period in the Implementation Plan.


______________________

/7/   Since the terms of this Agreement are the result of Focal's adoption under
 -
      Section 252(i) of the Act of the Teligent Agreement, the Parties agree
      that the term "Effective Date", for purposes of this SECTION 6.1.2, shall
                                                           ------------- 
      mean February 10, 1999.

                                      22
<PAGE>
 
           6.2.2  Focal shall provide to Ameritech, on a monthly basis, the
Switched Access Summary Usage Data (category 1150XX records) on magnetic tape
or, when available, via electronic data transfer using the EMR format.

           6.2.3  Ameritech shall provide to Focal, on a daily basis, the
Switched Access Detail Usage Data (category 1101XX records) on magnetic tape
no later than fourteen (14) days from the usage recording date. Ameritech shall
provide the information on magnetic tape or, when available, via electronic
data transfer (e.g., network data mover), using EMR format. Ameritech and
               ----
Focal shall use best efforts to utilize electronic data transfer.

           6.2.4  Each Party shall coordinate and exchange the billing account
reference ("BAR") and billing account cross reference ("BACR") numbers for the
Meet-Point Billing service. Each Party shall notify the other Party if the level
of billing or other BAR/BACR elements change, resulting in a new BAR/BACR
number.

      6.3  ERRORS OR LOSS OF ACCESS USAGE DATA.

           6.3.1 Errors may be discovered by Focal, the IXC or Ameritech. Each
Party agrees to use reasonable efforts to provide the other Party with 
notification of any discovered errors within two (2) Business Days of such 
discovery. All claims by a Party relating to errors or loss of access
usage data shall be made within thirty (30) calendar days from the date such
usage data was provided to that Party.

           6.3.2 In the event of a loss of data, both Parties shall cooperate
to reconstruct the lost data. If such reconstruction is not possible, the
Parties shall use a reasonable estimate of the lost data, based on twelve (12)
months of prior usage data; provided that if twelve (12) months of prior usage
                            --------
data is not available, the Parties shall base the estimate on as much prior
usage data that is available; provided, however, that if reconstruction is
                              --------  -------
required prior to the availability of at least three (3) months of prior usage
data, the Parties shall defer such reconstruction until three (3) months of
prior usage data is available.

      6.4  PAYMENT. The Parties shall not charge one another for the services
rendered pursuant to this ARTICLE V1.
                          -----------

      6.5  ADDITIONAL LIMITATIONS OF LIABILITY APPLICABLE TO MEET-POINT BILLING
ARRANGEMENTS.  In addition to the limitations of liability set forth in ARTICLE 
                                                                        -------
XXV1 and elsewhere in this Agreement, the following limitations on liability
----
shall apply with respect to the Meet-Point Billing arrangements described in 
this ARTICLE V1:
     ----------

           6.5.1  In the event of errors, omissions, or inaccuracies in data
received from either Party, the liability of the Party providing such data shall
be limited only to the provision of corrected data only. If data is lost, such
providing Party will develop a substitute based on past usage, as set forth in
SECTION 6.3.2.
--------------

                                      23
<PAGE>
 
           6.5.2  In recognition that neither Party is being compensated for
services rendered under this ARTICLE V1, in no event shall a Party's liability
                             ---------- 
to the other Party for any Loss relating to or arising out of any act(s) or
omission(s) in its performance of its obligations under this ARTICLE VI exceed
                                                             ----------  
$10,000 in any one (1) month period.

                                  ARTICLE VII
                           TRANSPORT AND TERMINATION
                           OF OTHER TYPES OF TRAFFIC
                                        
     7.1  INFORMATION SERVICES TRAFFIC.

          7.1.1 Each Party shall route Information Service Traffic which
originates on its own network to the appropriate information services
platform(s) connected to the other Party's network over the Local/IntraLATA
Trunks.

          7.1.2 The Party ("ORIGINATING PARTY") on whose network the
Information Services Traffic originated shall provide an electronic file
transfer or monthly magnetic tape containing recorded call detail information to
the Party ("TERMINATING PARTY") to whose information platform the Information
Services Traffic terminated.

          7.13 In accordance with procedures to be established by the
Implementation Team, the Terminating Party shall provide to the Originating
Party via electronic file transfer or magnetic tape all necessary information to
rate the Information Services Traffic to the Originating Party's Customers and
establish uncollectible reserves pursuant to the Terminating Party's agreements
with each information provider.

          7.1.4 The Originating Party shall bill and collect such information
provider charges and remit the amounts collected to the Terminating Party less:

           (a)  The Information Services Billing and Collection fee set forth at
                Item III of the Pricing Schedule; and

           (b)  An uncollectibles reserve calculated based on the uncollectibles
                reserve in the Terminating Party's billing and collection
                agreement with the applicable information provider; and

           (c)  Customer adjustments provided by the Originating Party.

The Originating Party shall provide to the Terminating Party sufficient
information regarding uncollectibles and Customer adjustments. The Terminating
Party shall pass through the adjustments to the information provider. Final
resolution regarding all disputed adjustments shall be solely, between the
Originating Party and the information provider.

                                      24
<PAGE>
 
          7.1.5 Nothing in this Agreement shall restrict either Party from
offering to its Telephone Exchange Service Customers the ability to block the
completion of Information Service Traffic.

     7.2  BLV/BLVI TRAFFIC.

          7.2.1 Busy Line Verification ("BLV") is performed when one Party's
Customer requests assistance from the operator bureau to determine if the called
line is in use; provided, however, the operator bureau will not complete the
                --------  -------                                         
call for the Customer initiating the BLV inquiry. Only one BLV attempt will be
made per Customer operator bureau call.

          7.2.2 Busy Line Verification Interrupt ("BLVI") is performed when one
Party's operator bureau interrupts a telephone call in progress after BLV has
occurred. The operator bureau will interrupt the busy line and inform the called
party that there is a call waiting. The operator bureau will only interrupt the
call and will not complete the telephone call of the Customer initiating the
BLVI request. The operator bureau will make only one BLVI attempt per Customer
operator telephone call and the applicable charge applies whether or not
the called party releases the line.

          7.2.3 Each Party's operator bureau shall accept BLV and BLVI
inquiries from the operator bureau of the other Party in order to allow  
transparent provision of BLV/BLVI Traffic between the Parties' networks. Each
Party shall route BLV/BLVI Traffic inquiries over separate direct trunks (and
not the Local/IntraLATA Trunks) established between the Parties' respective
operator bureaus. Unless otherwise mutually agreed, the Parties shall configure
BLV/BLVI trunks over the Interconnection architecture defined in ARTICLE III,
                                                                 ----------- 
consistent with the Plan.

          7.2.4 Each Party shall compensate the other Party for BLV/BLVI
Traffic as set forth at Item IV of the Pricing Schedule.

      7.3 TRANSIT SERVICE.

          7.3.1 Ameritech shall provide Focal Transit Service as provided in
this SECTION 7.3.
     -----------

          7.3.2 "TRANSIT SERVICE" means the delivery of certain traffic between
Focal and a third party LEC or CMRS provider by Ameritech over the
Local/IntraLATA Trunks. Transit Service shall be provided only at Ameritech's
Tandem Switches, and not at any Ameritech End Office. The following traffic
types will be delivered: (i) Local Traffic and IntraLATA Toll Traffic originated
from Focal to such third party LEC or CMRS provider and (ii) IntraLATA Toll
Traffic orginated from such third party LEC and terminated to Focal where
Ameritech carries such traffic pursuant to the Commission's primary toll carrier
("PTC") plan or other similar plan.

                                      25
<PAGE>
 
           7.3.3 The Parties shall compensate each other for Transit Service
as follows:

           (a)   For Local Traffic and IntraLATA Toll Traffic originating from
                 Focal that is delivered over the Transit Service ("TRANSIT
                 TRAFFIC"):

                 (1)  Focal shall:

                      (A) Pay to Ameritech a Transit Service charge as set forth
                          at Item V of the Pricing Schedule; and

                      (B) Reimburse Ameritech for any charges, including
                          switched access charges, that a third party LEC or
                          CMRS provider with whom Ameritech does not have a
                          Transit Service agreement similar to that set forth
                          in this SECTION 7.3 imposes or levies on Ameritech for
                                  -----------
                          delivery or termination of any such Transit Traffic.

                 (2)  Ameritech shall remit to Focal any access charges
                      Ameritech receives from such third party LEC or CMRS
                      provider in connection with the delivery of such Transit
                      Traffic.

           (b)   For Local Traffic and IntraLATA Toll Traffic that is to be
                 terminated to Focal from a third party LEC or CMRS provider (i)
                 that is not subject to PTC arrangements (regardless of whether
                 Ameritech is the PTC) and (ii) Ameritech has a transiting
                 arrangement with such third party LEC or CMRS provider which
                 authorizes Ameritech to deliver such traffic to Focal ("OTHER
                 PARTY TRANSIT AGREEMENT"), then Ameritech shall deliver such
                 Local Traffic and IntraLATA Toll Traffic to Focal in accordance
                 with the terms and conditions of such Other Party Transit
                 Agreement and such third party LEC or CMRS provider (and not
                 Focal) shall be responsible to pay Ameritech the applicable
                 Transit Service charge.

           (c)   For IntraLATA Toll Traffic which is subject to a PTC
                 arrangement and where Ameritech is the PTC, Ameritech shall
                 deliver such IntraLATA Toll Traffic to or from Focal in
                 accordance with the terms and conditions of such PTC
                 arrangement.

          7.3.4  While the Parties agree that it is the responsibility of each
third party LEC or CMRS provider to enter into arrangements to deliver Local
Traffic and IntraLATA Toll Traffic to Focal, they acknowledge that such
arrangements are not currently in place and an interim arrangement is necessary
to ensure traffic completion. Accordingly, until the earlier of (i) the date on
which either Party has entered into an arrangement with such third party LEC or
CMRS provider to deliver Local Traffic and IntraLATA Toll Traffic to Focal and
(ii) the termination of this Agreement, Ameritech will provide Focal with
Transit Service.

                                      26
<PAGE>
 
            7.3.5 Ameritech expects that all networks involved in transit
 traffic will deliver each call to each involved network with CCIS and the
 appropriate Transactional Capabilities Application Part ("TCAP") message to
 facilitate full interoperability and billing functions and, to the extent such
 CCIS and TCAP messages are delivered by the originating third party LEC or
 CMRS provider, Ameritech will deliver such information to the terminating
 third party LEC or CMRS provider. In all cases, Focal is responsible to follow
 the Exchange Message Record ("EMR") standard and exchange records with both
 Ameritech and the terminating LEC or CMRS provider to facilitate the billing
 process to the originating network.

            7.3.6 For purposes of this SECTION VII.3, Ameritech agrees that it
                                       -------------               
shall make available to Focal, at Focal's sole option, any transiting
arrangement Ameritech's offers to another LEC at the same rates, terms and
conditions provided to such other LEC.

                                 ARTICLE VIII
                 INSTALLATION, MAINTENANCE, TESTING AND REPAIR
                                        
      8.1   PLAN. Within ninety (90) days after the Effective Date, /8/ Focal 
                                                                     -
and Ameritech shall joint1y develop a plan (the "PLAN") which shall define and
detail:

            (a) standards to ensure that Interconnection trunk groups experience
                a grade of service, availability and quality in accordance with
                all appropriate relevant industry-accepted quality, reliability
                and availability standards and in accordance with the levels
                identified in SECTION 3.6;
                              -----------

            (b) the respective duties and responsibilities of the Parties with
                respect to the administration and maintenance of the
                Interconnections (including signaling) specified in ARTICLE III
                                                                    -----------
                and the trunk groups specified in ARTICLES IV and V, including
                                                  -----------     -
                standards and procedures for notification and discoveries of
                trunk disconnects;

            (c) disaster recovery and escalation provisions; and

            (d) such other matters as the Parties may agree.

   
      8.2   OPERATION AND MAINTENANCE. Each Party shall be solely responsible 
for the installation, operation and maintenance of equipment and facilities
provided by it for Interconnection, subject to compatibility and cooperative
testing and monitoring and the specific operation and maintenance provisions
for equipment and facilities used to provide Interconnection.


_______________________

/8/   Since the terms of this Agreement are the result of Focal's adoption under
 -
      Section 252(i) of the Act of the Teligent Agreement, the Parties agree
      that the term "Effective Date", for purposes of this SECTION 8.1, shall
                                                           -----------
      mean February 10, 1999.
      
                                      27
<PAGE>
 
Operation and maintenance of equipment in Virtual Collocation shall be in
accordance with the provisions of ARTICLE XII.
                                  -----------

      8.3  INSTALLATION, MAINTENANCE, TESTING AND REPAIR. The intervals for
installations, maintenance, joint testing, and repair of its facilities and
services associated with or used in conjunction with Interconnection will be
determined in accordance with the requirements of SECTION 3.8.
                                                  -----------
               
      8.4  ADDITIONAL TERMS. Additional terms regarding the installation,
maintenance, testing and repair of equipment and facilities used for
Interconnection shall be as set forth in the Implementation Plan.


                                  ARTICLE IX
                     UNBUNDLED ACCESS -- SECTION 251(C)(3)
                                        
      9.1  ACCESS TO NETWORK ELEMENTS.

           9.1.1 Ameritech shall provide Focal access to Ameritech's Network
Elements on an unbundled basis at any technically feasible point in accordance
with the terms and conditions of this ARTICLE IX and the requirements of the 
                                      ----------                    
Act. Ameritech shall provide Focal access to each unbundled Network Element,
along with all of such unbundled Network Element's features, functions, and
capabilities in accordance with the terms and conditions of ARTICLE II and as
                                                            ---------- 
required by the Act, in a manner that shall allow Focal to provide any
Telecommunications Service that can be offered by means of that Network Element;
provided that the use of such Network Element is consistent with the Act.
--------

          9.1.2  Notwithstanding anything to the contrary in this ARTICLE IX,
                                                                  ----------
Ameritech shall not be required to provide Network Elements beyond those
identified in 47 C.F.R. (S) 51.319 to Focal if:

          (1)    The Commission concludes that:


                 (A) such Network Element is proprietary or contains proprietary
                     information that will be revealed if such Network Element
                     is provided to Focal on an unbundled basis; and

                 (B) Focal could offer the same proposed Telecommunications
                     Service through the use of other, nonproprietary Network
                     Elements within Ameritech's network; or

          (2)    The Commission concludes that the failure of Ameritech to
                 provide access to such Network Element would not decrease the
                 quality of, and would not increase the financial or
                 administrative cost of, the Telecommunications

                                      28
<PAGE>
 
                 Service Focal seeks to offer, compared with providing that
                 service over other unbundled Network Elements in Ameritech's
                 network.

          9.1.3  Ameritech shall be required to make available Network Elements
only where such Network Elements, including facilities and software necessary
to provide such Network Elements, are available. If Ameritech makes available
Network Elements that require special construction, Focal shall pay to Ameritech
any applicable special construction charges.

     9.2  NETWORK ELEMENTS /9/.  At the request of Focal, Ameritech shall
                            -
provide Focal access to the following Network Elements on an unbundled basis:

          9.2.1  Local Loops, as more fully described on SCHEDULE 9.2.1;
                                                         --------------

          9.2.2  The Network Interface Device, as more fully described on
SCHEDULE 9.2.2;
--------------

          9.2.3  Switching Capability, as more fully described on SCHEDULE 
                                                                  --------
9.2.3;
-----

          9.2.4  Interoffice Transmission Facilities, as more fully described on
SCHEDULE 9.2.4;
--------------

          9.2.5  Signaling Links and Call-Related Databases, as more fully 
described on SCHEDULE 9.2.5;
             --------------

          9.2.6  Operations Support Systems ("OSS") functions, to be used in
conjunction with other Network Elements, as more fully described on SCHEDULE   
                                                                    --------
9.2.6; and
-----

          9.2.7  Operator Services and Directory Assistance, as more fully 
described on SCHEDULE 9.2.7.
             --------------

     9.3  COMBINATION OF NETWORK ELEMENTS.

          9.3.1  Ameritech shall provide Network Elements to Focal in a manner
that shall allow Focal to combine such Network Elements (a "Combination") in
order to provide a Telecommunications Service. When purchasing a Combination,
Focal will have access to all features and capabilities of each individual
Network Element that comprises such Combination and the specific technical and
interface requirements for each of the Network Elements shall apply, 


----------------------

/9/  Notwithstanding anything contrary in this Agreement, in the event the FCC
 -
     or a court of competent jurisdiction determines that incumbent local
     exchange carrier(s) generally are not required and/or Ameritech is not
     required to make available one or more Network Element(s) provided by
     Ameritech under this Agreement, Ameritech shall have the right to
     immediately delete such Network Element(s) and the provisions related
     thereto contained in this Agreement.

                                      29
<PAGE>
 
except to the extent not technically feasible given the specific manner in which
Focal has requested that the elements be combined.

          9.3.2 Except upon the request of Focal, Ameritech shall provide
Network Elements separately from each other, and shall not separate Network
Elements it normally provides in combination into separate Network Elements.

          9.3.3 Upon Focal's request, Ameritech shall perform the functions
necessary to combine Ameritech's Network Elements in any manner, even if those
elements are not ordinarily combined in Ameritech's network; provided that such
                                                             --------         
combination is (i) technically feasible and (ii) would not impair the ability of
other Telecommunications Carriers to obtain access to unbundled Network Elements
or to Interconnect with Ameritech's network. In addition, upon a request of
Focal that is consistent with the above criteria, Ameritech shall perform the
functions necessary to combine Ameritech's Network Elements with elements
possessed by Focal in any technically feasible manner to allow Focal to provide
a Telecommunications Service.

          9.3.4 Ameritech shall make available to Focal the following
Combinations at the rates set forth at Item V of the Pricing Schedule:
                                              
                9.3.4.1  Unbundled Element Platform with Operator Services and
                         Directory Assistance. This Combination is described on
                         SCHEDULE 9.3.4.
                         --------------

                9.3.4.2  Loop Combination. This Combination is described on 
                         SCHEDULE 9.3.4.
                         --------------

                9.3.4.3  Switching Combination #1. This Combination is described
                         on SCHEDULE 9.3.4.
                            --------------  

          9.3.5 The following Network Elements and Combinations shall be 
requested by Focal in accordance with SECTION 9.6:
                                      -----------

                9.3.5.1  Unbundled Loop - Distribution.

                9.3.5.2  Unbundled Loop - Concentrators/Multiplexers.

                9.3.5.3  Unbundled Loop - Feeder.

                9.3.5.4  Loop/Network Combination. This Combination is described
                         on SCHEDULE 9.3.5.  
                            --------------

                9.3.5.5  Switching Combination #2. This Combination is described
                         on SCHEDULE 9.3.5.
                            --------------

                                      30
<PAGE>
 
                9,3.5.6  Switching Combination #3. This Combination is 
                         described on SCHEDULE 9.3.5.
                                      --------------
                9.3.5.7  Switched Data Services. This Combination is described 
                         on SCHEDULE 9.3.5.
                            --------------

                9.3.5.8  Unbundled Element Platform without Operator Services
                         and Directory Assistance. This Combination is described
                         on SCHEDULE 9.3.5. 
                            --------------

          9.3.6 Any request by Focal for Ameritech to provide any Combination
other than as set forth in SECTION 9.3.4, to combine the unbundled Network
                           -------------
Elements of Ameritech with Focal, or to perform any other function under this
SECTION 9.3 shall be made by Focal in accordance with SECTION 9.6
-----------                                           ----------- 

     9.4  NONDISCRIMINATORY ACCESS TO AND PROVISION OF NETWORK ELEMENTS

          9.4.1 Subject to SECTION 9.4.4, the quality of an unbundled Network
                           ---------------                                  
Element as well as the quality of the access to such unbundled Network Element
that Ameritech provides to Focal shall be the same for all Telecommunications
Carriers requesting access to such Network Element.

          9.4.2 Subject to SECTION 9.4.4, the quality of a Network Element, as
                           -------------
well as the quality of the access to such Network Element, that Ameritech
provides to Focal hereunder shall be at least equal in quality to that which
Ameritech provides to itself, its subsidiaries, Affiliates and any other person,
unless Ameritech proves to the Commission that it is not technically feasible to
provide the Network Element requested by Focal or access to such Network Element
at a level of quality that is equal to that which Ameritech provides to itself.

          9.4.3 Ameritech shall provide Focal access to Network Elements and
Operations Support Systems functions, including the time within which Ameritech
provisions such access to Network Elements, on terms and conditions no less
favorable than the terms and conditions under which Ameritech provides such
elements to itself, its subsidiaries, Affiliates and any other person, except as
may be provided by the Commission pursuant to SECTION 9.1.2.
                                              -------------

          9.4.4 Upon the request of Focal, Ameritech shall provide to Focal a
Network Element and access to such Network Element that is different in quality
to that required under SECTIONS 9.4.2 and 9.4.3, unless Ameritech proves to the
                       --------------     -----                                
Commission that it is not technically feasible to provide the requested Network
Element or access to such Network Element at the requested level of quality. Any
request by Focal for Ameritech to provide any Network Element or access thereto
that is different in quality shall be made by Focal in accordance with SECTION
                                                                       -------
9.6.
---

                                      31
<PAGE>
 
     9.5  PROVISIONING OF NETWORK ELEMENTS.

          9.5.1 Ameritech shall provide Focal unbundled Network Elements as set
forth on SCHEDULE 9.5.
         ------------

          9.5.2 Ameritech shall provide Focal access to the functionalities for
Ameritech's pre-ordering, ordering, provisioning, maintenance and repair and
billing functions of the Operations Support Systems functions that relate to the
Network Elements that Focal purchases hereunder. Access to such functionalities
for the Operations Support Systems functions shall be as provided in SCHEDULE
                                                                     --------
9.2.6 and the Implementation Plan.
-----

          9.5.3 Prior to submitting an order for a Network Element which 
                   -------------                                              
replaces, in whole or in part, a service offered by Ameritech or any other
telecommunications provider for which Ameritech changes a primary local
exchange carrier, Focal shall comply with the requirements of SECTION 10.11.1.
                                                              ---------------

     9.6  AVAILABILITY OF ADDITIONAL OR DIFFERENT QUALITY NETWORK ELEMENTS.

Any request by Focal for access to a Network Element or a Combination or a
standard of quality thereof that is not otherwise provided by the terms of this
Agreement at the time of such request shall be made pursuant to a Bona Fide
Request and shall be subject to the payment by Focal of all applicable costs in
accordance with Section 252(d)(1) of the Act to process, develop, install and
provide such Network Element, Combination or access.

     9.7  PRICING OF UNBUNDLED NETWORK ELEMENTS.


          9.7.1 Ameritech shall charge Focal the non-recurring and monthly
recurring rates for unbundled Network Elements (including the monthly recurring
rates for these specific Network Elements, service coordination fee, and Cross-
Connect charges) as specified at Item V of the Pricing Schedule. If Focal
requests or approves an Ameritech technician to perform services in excess of or
not otherwise contemplated by the Line Connection Service, Ameritech may charge
Focal for any additional and reasonable labor charges to perform such services.

          9.7.2 In addition to any other applicable charges under this ARTICLE 
                                                                       -------
IX, if Focal purchases unbundled Local Switching elements, Focal shall pay
--
Ameritech:

          (a)  for interstate minutes of use traversing such unbundled Local
               Switching elements, the carrier common line charge described in
               47 C.F.R. (S) 69.105 and a charge equal to seventy-five percent
               (75%) of the interconnection charge describe in 47 C.F.R. (S)
               69.124, only until the earliest of the following, and not
               thereafter:

               (1)  June 30, 1997;

                                      32
<PAGE>
 
                (2)  The later of the effective date of a final FCC decision in
                     CC Docket No. 94-45, Federal-State Joint Board on
                                          ----------------------------
                     Universal Service, or the effective date of a final FCC
                     -------------------                                    
                     decision in a proceeding, to consider reform of interstate
                     access charges; or

                (3)  The date on which Ameritech is authorized to offer in-
                     region interLATA service in Michigan pursuant to Section
                     271 of the Act; and

           (b)  for intrastate toll minutes of use traversing such unbundled
                Local Switching elements, intrastate access charges comparable
                to those listed in SECTION 9.7.2(A) and any explicit intrastate
                                   ----------------
                universal service mechanism based on access charges, only until
                the earliest of the following, and not thereafter:

                (1) June 30, 1997;
                                                                              
                                                                              
                (2) The effective date of the Commission's decision that      
                    Ameritech may not assess such charges; or                 
                                                                              
                (3) The date on which Ameritech is authorized to offer in-    
                    region interLATA service in Michigan pursuant to Section  
                    271 of the Act.                                           

          9.7.3 If Focal orders a Combination identified in SECTION 9.3.4 and
                                                            -------------
the provision of any such Combination requires Ameritech to modify any of its
existing systems, service development processes or its network (beyond that
required for Ameritech to provision its own retail services) to provide access
to such Combination, Focal shall be required to compensate Ameritech for any
costs incurred to Provide access to such Combination.

      9.8 BILLING. Ameritech shall bill Focal for access to unbundled Network
Elements pursuant to the requirements of ARTICLE XXVII to this Agreement.
                                         -------------       

      9.9 MAINTENANCE OF UNBUNDLED NETWORK ELEMENTS.

          9.9.1 Ameritech shall provide maintenance of Loops and Combinations
that include Loops as set forth in SCHEDULE 10.13.
                                   ---------------

          9.9.2 If (i) Focal reports to Ameritech a suspected failure of a
Network Element, (ii) Focal requests a dispatch, (iii) Ameritech dispatches a
technician, and (iv) such trouble was not caused by Ameritech's facilities or
equipment, then Focal shall pay Ameritech a trip charge and time charges as set
forth at Item V of the Pricing Schedule.


                                      33
<PAGE>
 
      9.10 STANDARDS OF PERFORMANCE.

           9.10.1 Ameritech shall provide to Focal access to unbundled Network
Elements (i) in accordance with SECTION 9.4 as determined by this SECTION 9.10
                                ------------                      ------------
(including any Combinations, service levels and intervals that may be requested
by Focal and agreed upon by the Parties pursuant to a Bona Fide Request) and
(ii) as required by the Commission (collectively, the "AMERITECH NETWORK ELEMENT
PERFORMANCE BENCHMARKS").

           9.10.2 To determine Ameritech's compliance with the Ameritech
Network Element Performance Benchmarks, Ameritech shall maintain records of
specific criteria listed in SCHEDULE 9.10 which criteria are the criteria that
                            -------------                                    
Ameritech currently measures to evaluate its provision of unbundled Network
Elements and (ii) such additional criteria the Parties agree upon regarding
Ameritech's compliance with different performance levels and intervals of such
Network Elements (and Combinations thereof) requested by Focal and provided by
Ameritech pursuant to Section 9.6 and a Bona Fide Request (each, a "NETWORK  
                      -----------                                           
ELEMENT PERFORMANCE ACTIVITY") relating to the access to unbundled Network
Elements Ameritech provides to itself, its subsidiaries and Affiliates (the
"AMERITECH NE RECORDS") and parallel records of the access to unbundled Network
Elements Ameritech provides to (i) Focal (the "FOCAL NE RECORDS") and (ii)
other LECs in the aggregate (the "OTHER LEC NE RECORDS"). In addition, the
Parties may supplement the Network Element Performance Activities as
provides in SECTION 18.6. The criteria will be revised in accordance with
            ------------                                                 
the procedures set forth in the Implementation Plan if Ameritech no longer 
measures a criterion in assessing, its performance in providing Network 
Elements or beings measuring additional criteria.

          9.10.3 Ameritech shall provide to Focal for each Reporting Period, by
the twenty-second (22nd) day of the following month, in a self-reporting
format the Ameritech NE Records, the Focal NE Records and the Other LEC NE
Records so that the Parties can determine Ameritech's compliance with the
Ameritech Network Element Performance Benchmarks. If (i) Ameritech fails to
comply with an Ameritech Network Element Performance Benchmark with respect to a
Network Element Performance Activity for a Reporting Period, (ii) the sample
size of the Network Element Performance Activity measured for such Reporting
Period is statistically valid and (iii) the amount by which the applicable
Ameritech Network Element Performance Activity deviates from the corresponding
Network Element Performance Benchmark is statistically significant, then
Ameritech shall have committed a "SPECIFIED PERFORMANCE BREACH". Notwithstanding
anything to the contrary in this SECTION 9.10.3, the Parties acknowledge that
                                 --------------
(x) Ameritech shall not be required to provide to Focal those Other LEC NE
Records that correspond to and measure a level of quality and performance levels
and intervals of unbundled Network Elements that are requested by an Other LEC
pursuant to 47 C.F.R. (S)51.311(c) and SECTION 9.6 and which are superior to
                                       -----------
that which Ameritech provides to Focal hereunder, (y) the Other LEC NE Records
shall be provided to Focal on an aggregate basis and (z) such Other LEC NE
Records shall be provided to Focal in a manner that preserves the
confidentiality of each other LEC and any of such LEC's proprietary information
(including CPNI).

          9.10.4 In no event shall Ameritech be deemed to have committed a
Specified Performance Breach if Ameritech's failure to meet or exceed a Network
Element Performance

                                      34
<PAGE>
 
Activity is caused by a Delaying Event. If a Delaying Event (i) prevents
Ameritech from performing a certain function or action that affects a Network
Element Performance Activity, then such occurrence shall be excluded from the
calculation of such Network Element Performance Activity and the determination
of Ameritech's compliance with the applicable Ameritech Network Element
Performance Benchmark or (ii) only suspends Ameritech's ability to timely
perform such Network Element Performance Activity, then the applicable time
frame in which Ameritech's compliance with the Ameritech Network Element
Performance Benchmark is measured shall be extended on a like-time basis equal
to the duration of such Delaying Event.

          9.10.5    Upon the occurrence of a Specified Performance Breach by
Ameritech, Focal may forego the dispute escalation procedures set forth in
SECTION 28.3 and (i) bring an action against Ameritech in an appropriate Federal
-------------                                                                   
district court, (ii) file a complaint against Ameritech with the FCC pursuant
to Sections 207 or 208 of the Act, (iii) seek a declaratory ruling from the
FCC, (iv) file a complaint in accordance with the rules, guidelines and
regulations of the Commission or (iv) seek other relief under Applicable Law.

          9.10.6    Focal shall also be entitled to any Credit Allowances
pursuant to the same terms and conditions that the Ameritech offers Credit
Allowances to its Customers, including those described on SCHEDULE 10.9.6.
                                                          ----------------

          9.10.7    The Parties' agreement to the procedures set forth in this
SECTION 9.10 shall not (i) relieve either Party of its obligations to perform
------------                                                                   
any other duties under this Agreement or (ii) constitute a waiver of a right of
either Party to claim that the party requirements of this Agreement and of the 
Act have or have not been met.

                                   ARTICLE X
                 RESALE AT WHOLESALE RATES--SECTION 251(C)(4)

     10.1 TELECOMMUNICATIONS SERVICES AVAILABLE FOR RESALE AT WHOLESALE RATES.
Commencing on the date on which the Commission approves this Agreement, at the
request of Focal, Ameritech will make available to Focal for resale at wholesale
rates those Telecommunications Services that Ameritech provides at retail to
subscribers who are not Telecommunications Carriers, as required in Section 
251(c)(4) of the Act. Subject to the terms, conditions and limitations set forth
in this Agreement, Ameritech will make available to Focal for such resale all
Telecommunications Services which it offers to its retail Customers, including
the following categories of Telecommunications Services (the "RESALE SERVICES") 
as listed on SCHEDULE 10.1.
             -------------

          (i)       Local Service - Residence, as described in the applicable
                    tariff,

          (ii)      Local Service - Business, as described in the applicable
                    tariff,

          (iii)     Message Toll Service, as described in the applicable tariff,

                                      35
<PAGE>
 
          (iv)      PBX Trunk, as described in the applicable tariff;

          (v)       ISDN Direct Service, as described in the applicable tariff;

          (vi)      ISDN Prime Services, as described in the applicable tariff;

          (vii)     Ameritech Centrex Service, as described in the applicable
                    tariff;

          (viii)    Dedicated Communications Services, as described in the
                    applicable tariff;

          (ix)      Inbound Services, as described in the applicable tariff; and

          (x)       Customer Owned Pay Telephone Services, as described in the
                    applicable tariff.

The Resale Services shall be made available to Focal at the rates set forth at
Item VI of the Pricing Schedule.

     10.2 OTHER SERVICES. Ameritech may, at its sole discretion, and as agreed
to by Focal, make available to Focal under this Agreement services other than
Telecommunications Services (e.g., voicemail) for resale at rates, terms and
conditions agreed upon by the Parties.

     10.3 LIMITATIONS ON AVAILABILITY OF RESALE SERVICES.

The following limitations shall apply to Resale Services:

          10.3.1    Any Telecommunications Services which Ameritech offers to
existing retail subscribers, but not to new subscribers ("GRANDFATHERED
SERVICES") are listed on SCHEDULE 10.3.1. SCHEDULE 10.3.1 may be revised or
                         ---------------  ---------------   
supplemented from time to time to include those additional services that
Ameritech may, in its discretion and to the extent permitted by Applicable Law,
classify as Grandfathered Services. Ameritech agrees to make Grandfathered
Services available to Focal for resale to any Customer of Ameritech that
subscribes to a Grandfathered Service from Ameritech at the time of its
selection of Focal as its primary local exchange carrier. If a local
Telecommunications Service is subsequently classified as a Grandfathered Service
by Ameritech, Ameritech agrees to continue to sell such Grandfathered Service
(subject to the terms of SECTION 10.3.2) to Focal for resale to Focal's
                         --------------
Customers that subscribe to such Grandfathered Service at the time it is so
classified by Ameritech. Grandfathered Services shall be made available to Focal
at wholesale rates determined in accordance with the Act. To the extent that
Ameritech is unable to provide wholesale systems support and billing within the
first ninety (90) days from the date each Focal Resale Customer is provided such
Grandfathered Service, Ameritech shall retroactively apply such wholesale rate
as a credit to Focal and will bill such service to Focal from its retail billing
systems.

                                      36
<PAGE>
 
          10.3.2    Any Telecommunication Services which Ameritech currently
intends to discontinue offering to any retail subscriber ("SUNSETTED SERVICES")
are set forth on SCHEDULE 10.3.1. SCHEDULE 10.3.1 may be revised or supplemented
                 ---------------  ---------------
from time to time to include those additional Telecommunications Services that
Ameritech may, in its discretion and to the extent permitted by Applicable Law,
classify as Sunsetted Services. Ameritech agrees to make Sunsetted Services
available to Focal for resale to Focal's Customers who are subscribers to the
Sunsetted Service either from Ameritech or Focal at the time so classified
(subject to the provisions of SECTION 10.3.1 if such Sunsetted Service was
                              -------------- 
previously classified as a Grandfathered Service) until the date such service
is discontinued.

          10.3.3    Each Party acknowledges that Resale Services shall be
available to Focal on the same basis as offered by Ameritech to itself or to any
subsidiary, Affiliate, or any other person to which Ameritech directly provides
the Resale Services, including Ameritech's retail Customers and other
resellers of Ameritech's Telecommunications Services (i) on1y in those service
areas in which such Resale Services (or any feature or capability thereof)
are offered by Ameritech to itself or to any subsidiary, Affiliate, or any
other person, including Ameritech's retail Customers and (ii) to the same extent
as Ameritech's retail Telecommunications Services are subject to the
availability of facilities.

     10.4 ADDITIONAL CHARGES FOR RESALE SERVICES. In addition to the rates set
forth at Item VI of the Pricing Schedule, Focal shall pay Ameritech (i) for any 
applicable charges or fees, if any, incident to the establishment or provision 
of the Resale Services requested by Focal, including channel charges, initial 
non-recurring charges and construction charges and (ii) the applicable non
discounted end user common line charge as set forth in F.C.C. No. 2, Section 4.

     10.5 RESTRICTIONS ON RESALE SERVICES.
          
          10.5.1    To the extent provided by Applicable Law, including Section
357(2) of the Michigan Telecommunications Act, Focal may not offer Resale
Services that are made available only to residential Customers or to a limited
class of residential Customers to classes of Customers that are not eligible to
subscribe to such services from Ameritech.

          10.5.2    Ameritech shall not be required to provide to Focal Resale 
Services offered at a special promotional rate if:

          (a)       Such promotions involve rates that will be in effect for no 
                    more than ninety (90) days; and 

          (b)       Such promotional offerings are not used to evade the
                    wholesale rate obligation; for example, by making available
                    a sequential series of ninety (90) day promotional rates.

                                      37
<PAGE>
 
          10.5.3    Nothing in this Agreement shall require Ameritech to provide
to Focal promotional service elements that are not Telecommunications Services
(i.e., customer-premises equipment).
 ---                             

          10.5.4    Unless permitted by the Commission or FCC after the
Effective Date, Focal shall not utilize Resale Services to avoid applicable
access charges.

          10.5.5    As provided in the Act, Focal may not purchase Resale
Services unless such services are resold to a person other than Focal, its
subsidiaries and Affiliates.

          10.5.6    Ameritech may impose additional restrictions on Focal's sale
of Resale Services only as permitted by the Act, Commission and the FCC.

     10.6 NEW RESALE SERVICES: CHANGES IN PROVISION OF RESALE SERVICES.
Ameritech shall, via tariff filings and as provided in the Implementation Plan,
notify Focal of any changes in the terms and conditions under which Ameritech
offers Resale Services, including the introduction of any new features, 
functions, services or promotions. If a tariff filing provides less than 
forty-five (45) days' notice, Ameritech shall provide not less than forty-five
(45) days' advance notice of such introduction. In addition, Ameritech shall
furnish Focal with reasonable quantities of publicly available collateral
information regarding the Resale Services.

     10.7 OPERATIONS SUPPORT SYSTEMS FUNCTIONS. Ameritech shall provide Focal,
upon Focal's request and pursuant to the Implementation Plan, nondiscriminatory
access to Ameritech's Operations Support Systems functions for pre-ordering,
ordering, provisioning, maintenance and repair, and billing.

     10.8 NONDISCRIMINATORY PROVISION OF RESALE SERVICES.

          10.8.1    Resale Services made available by Ameritech for resale
hereunder and Operations Support Systems functions for ordering, provisioning, 
repair, maintenance and billing shall be equal in quantity to that provided by 
Ameritech to itself or to any subsidiary, Affiliate or any other person to which
Ameritech directly provides the Resale Service, including Ameritech's retail 
Customers.

          10.8.2    Ameritech shall provision Resale Services with the same
timeliness that such Resale Services are provisioned to Ameritech's 
subsidiaries, Affiliates, or other persons to whom Ameritech directly provides
the Resale Service, including Ameritech's retail Customers.

     10.9 STANDARDS OF PERFORMANCE.

          10.9.1    Ameritech shall provide Resale Services to Focal (i) in
accordance with SECTION 10.8 as determined by this SECTION 10.9 and (ii) as
                ------------                       ------------
required by the Commission (collectively, the "RESALE PERFORMANCE BENCHMARKS").

                                      38
<PAGE>
 
          10.9.2    To determine Ameritech's compliance with the Resale
Performance Benchmarks, Ameritech shall maintain records of specific criteria
listed in SCHEDULE 10.9.2 (each, a "RESALE PERFORMANCE ACTIVITY") relating to
          ---------------
Resale Services it provides to itself and to its subsidiaries, Affiliates and
Ameritech's retail Customers (the "AMERITECH RESALE RECORDS") and parallel
records of the Resale Services provided to (i) Focal (the "FOCAL RECORDS") and
(ii) on an aggregate basis, resellers of Telecommunications Services other than
Focal (the "OTHER RESELLER RECORDS").

     Ameritech believes, after good faith inquiry, that SCHEDULE 10.9.2 is a
                                                        ---------------
complete and accurate description of all criteria used as of the Effective Date
by Ameritech to measure Resale Services provided to itself and to its
subsidiaries, Affiliates or its Retail Customers. The criteria will be revised 
in accordance with the procedures set forth in the Implementation Plan if 
Ameritech no longer measures a criterion in assessing its performance in
providing such Resale Service to Ameritech's retail Customers or begins
measuring additional criteria.

          10.9.3    Ameritech shall provide to Focal for each Reporting Period, 
by the twenty-second (22nd) day of the following month, in a self-reporting 
format, the Ameritech Resale Records, the Focal Resale Records and the Other 
Reseller Records so that the Parties can determine Ameritech's compliance with 
the Resale Performance Benchmarks. If (i) Ameritech falls to comply with a 
Resale Performance Benchmark with respect to a Resale Performance Activity for 
a Reporting Period, (ii) the sample size of the Resale Performance Activity 
measured for such Reporting Period is statistically valid, and (iii) the amount 
by which the applicable Resale Performance Activity deviates from the 
corresponding Resale Performance Benchmark is statistically significant, then 
Ameritech shall have committed a "SPECIFIED PERFORMANCE BREACH." 
Notwithstanding anything to the contrary in this SECTION 10.9.3, the Parties 
                                                 --------------
acknowledge that the Other Reseller Records shall be provided to Focal (x) on 
an aggregate basis and (y) in a manner that preserves the confidentiality of 
each other reseller and any of such reseller's proprietary information 
(including CPNI).

          10.9.4    In no event shall Ameritech be deemed to have committed a
Specified Performance Breach if Ameritech's failure to meet or exceed a Resale
Performance Activity is caused by a Delaying Event. If a Delaying Event (i)
prevents Ameritech from performing a certain function or action that affects a 
Resale Performance Activity, then such occurrence shall be excluded from the 
calculation of such Resale Performance Activity and the determination of 
Ameritech's compliance with the applicable Resale Performance Benchmark or
(ii) only suspends Ameritech's ability to timely perform such Resale Performance
Activity, then the applicable time frame in which Ameritech's compliance with
the Resale Performance Benchmark is measured shall be extended on a like-time
basis equal to the duration of such Delaying Event.

          10.9.5    Upon the occurrence of a Specified Performance Breach by
Ameritech, Focal may elect one of the following two remedies:

           (a)      Forego the dispute escalation procedures set forth in 
                    Section 28.3 and (i) bring an action against Ameritech in 
                    ------------
                    an appropriate Federal district court, (ii)

                                      39
<PAGE>
 
                    file a complaint against Ameritech with the FCC pursuant to
                    Sections 207 or 208 of the Act, (iii) seek a declaratory
                    ruling from the FCC, (iv) file a complaint in accordance
                    with the rules, guidelines and regulations of the Commission
                    or (v) seek other relief under Applicable Law; or

          (b)       Ameritech shall pay to Focal as liquidated damages any
                    amounts that Focal is entitled to receive under then
                    existing Commission procedures relating to the failure by
                    Ameritech to comply with the Commission performance
                    standards.

          10.9.6    Focal shall also be entitled to any Credit Allowances
pursuant to the same terms and conditions that Ameritech offers Credit
Allowances to its retail Customers, including those described on SCHEDULE 
                                                                 --------    
10.9.6.
------

          10.9.7      The Parties' agreement to the procedures set forth in this
SECTION 10.9 shall not (i) relieve either Party of its obligations to perform
------------
any other duties under this Agreement or (ii) constitute a waiver of a right of
either Party to claim that the parity requirements of this Agreement and of the
Act have or have not been met.

    10.10 BRANDING
          
          10.10.1     If Operator Call Completion or Directory Assistance
Service is a feature of an offered Resale Service, Ameritech shall rebrand or
unbrand such features of such offered Resale Service as requested by Focal for
Focal's Customers, unless Ameritech places a restriction on such rebranding or
unbranding that is approved by the Commission as reasonable and
nondiscriminatory, such as proving that Ameritech lacks the capability to comply
with such rebranding or unbranding request.

          10.10.2     Ameritech shall make available to Focal, upon Focal's
request, the ability to route:

          (i)       Local Directory Assistance calls dialed by Focal's Customers
                    directly to Focal Directory Assistance Services platform, to
                    the extent such routing is technically feasible; and

          (ii)      Local Operator Services calls (0+, 0-) dialed by Focal
                    Customers directly to the Focal Local Operator Services
                    platform. Such traffic shall be routed over trunk groups
                    between Ameritech End Offices and the Focal Local Operator
                    Services platform, using standard Operator Services dialing
                    protocols of 0+ or 0-, to the extent such routing is
                    technically feasible.

The routing capabilities described above will be implemented according to the
Implementation Plan. To the extent technically feasible, all direct routing
capabilities described in this SECTION 10.10.2 shall permit Focal Customers to
                               ---------------
dial the same telephone numbers for Ameritech Directory

                                      40
<PAGE>
 
Assistance and Local Operator Service that similarly situated Ameritech
Customers dial for reaching equivalent Ameritech services.

          10.10.3   Notwithstanding anything to the contrary in this Agreement, 
the Parties agree that Ameritech shall have no obligation to unbrand or rebrand 
its service technicians or trucks, any customer premises equipment, other 
customer-owned facilities or its outside plant.

          10.10.4   Focal shall not, without Ameritech's prior written consent,
offer any Resale Service to any Customer under any brand name of Ameritech, its
subsidiaries or its Affiliates, nor shall Focal state or imply that there is any
joint business association or any similar arrangement with Ameritech in the
provision of Resale Service to Focal's Customers, except to the extent Focal
deems it necessary to advise its Customers that Ameritech's personnel will
perform work on behalf of Focal under this Agreement.

          10.10.5   In those instances where Focal requires Ameritech personnel
to interface directly with Focal Customers, either orally in person or by
telephone, or in writing, such personnel shall identify themselves as
Ameritech's employees representing Focal.

          10.10.6   Any "NO ACCESS" cards and time and materials invoices
furnished during service calls by Ameritech personnel to Focal Customers shall
be available to Focal for review and shall be provided to Focal Customers in
an unbranded form.

          10.10.7   In no event shall Ameritech personnel acting on behalf of
Focal pursuant to this Agreement provide information to any existing Focal
Customer about Ameritech products or services.

          10.10.8   Focal shall pay Ameritech's costs, if any, pursuant to the
pricing standard in Section 252(d)(1) of the Act and in such amounts or levels
as determined by the Commission for providing any requested branding under this 
SECTION 10.10
-------------

   10. 11 PRIMARY LOCAL EXCHANGE AND INTEREXCHANGE CARRIER SELECTIONS.

          10.11.1   The Parties shall apply all of the principles set forth in
47 C.F.R. (S) 64.1100 to the process for Customer selection of a primary
local exchange carrier. Ameritech shall not require a disconnect order from an
Focal Customer, or another LEC, in order to process an Focal order for Resale
Service for an Focal Customer. Ameritech shall advise Focal whenever an Focal
Customer has selected another primary local exchange carrier by giving notice
via an electronic interface within twenty-four (24) hours of the change being
provisioned by Ameritech. Until the FCC or the Commission adopts final rules and
procedures regarding a Customer's selection of a primary local exchange carrier,
Focal shall deliver to Ameritech a representation of authorization in the form 
set forth on SCHEDULE 10.11.1 that applies to all orders submitted by Focal 
             ----------------
under this Agreement that require a primary local exchange carrier change. Such 
representation of authorization shall be delivered to Ameritech prior to the 
first order submitted by Focal. Focal shall retain on file all applicable 
Documentation of Authorization (as defined in SCHEDULE 10.11.1),
                                              ----------------
                                      41
<PAGE>
 
including letters of agency, relating to the Customer's selection of Focal as
its primary local exchange carrier, which documentation shall be available for
inspection by Ameritech at its request during normal business hours.

          10.11.2  Carrier Selection Disputes. If any disputes should occur
                   --------------------------
concerning the selection of primary local exchange carriers by the Customers of
a Party, the following dispute escalation procedures shall be followed:

          (a)  If a Customer denies authorizing a change in his or her primary
               local exchange carrier selection to a different LEC
               ("UNAUTHORIZED SWITCHING"), Ameritech shall switch that Customer
               back to Focal in accordance with the terms of Michigan Bell
               Telephone Company Tariff, MPSC #20R, Part 22 (Resale Local
               Exchange Services) (the "RESALE TARIFF"). However, in the case of
               unauthorized changes of Focal Customers to Ameritech, Ameritech
               shall also have the duties of the "Carrier" as enumerated in such
               Resale Tariff, but will pay the $50 compensation, described in
               the Resale Tariff, to Focal.

          (b)  If Ameritech reports or otherwise provides information on
               unauthorized primary local exchange carrier changes to the FCC,
               the Commission or any other governmental entity, Ameritech agrees
               to report on Focal unauthorized primary local exchange carrier
               changes separately from unauthorized PIC changes.

          (c)  The Parties agree that in the event the Resale Tariff is
               withdrawn by Ameritech or materially revised, they will promptly
               meet and negotiate in good faith a revised procedure for
               resolving carrier selection disputes. If the Parties are unable
               to agree upon such revised procedure within thirty (30) days of a
               Party's request to commence the negotiations, the dispute
               resolution procedures set forth in SECTION 28.3 will be
                                                  ------------
               implemented.

          10.11.3  When Ameritech receives an order for Resale Service from
Focal for Focal's Customer, and Ameritech currently provides resale local
exchange telecommunications services to another carrier ("CARRIER OF RECORD")
for the same Customer, Ameritech shall notify such Carrier of Record of such
order coincident with processing the order. It shall then be the responsibility
of the Carrier of Record and Focal to resolve any issues related to that
Customer. Focal agrees to indemnify and hold Ameritech harmless against any and
all Losses that may result from Ameritech acting under this SECTION 10.11.3.
                                                            ---------------

          10.11.4  When notified by Focal or through the Customer Access Record
Exchange system (CARE) that a Customer has changed its presubscribed
interexchange carrier ("PIC") selection only from one IXC to another IXC,
Ameritech shall provision the PIC only change. Ameritech will modify its process
to conform with industry accepted standards and the requirements of the FCC or
the Commission.

                                      42
<PAGE>
 
     10.12  FUNCTIONALITY REQUIRED TO SUPPORT RESALE SERVICE.

            10.12.1  Directory Listing Requirements. Ameritech shall make
                     ------------------------------                    
available to Focal for Focal Customers directory listings in accordance with the
provisions of ARTICLE XV.
              ----------

            10.12.2  LEC - Assigned Telephone Calling Card Numbers. Effective as
                     ---------------------------------------------
of the date of a Customer's subscription to Focal's service, Ameritech will
block the LEC-assigned telephone line calling card number (including area code)
("TLN") from the Line Identification Database ("LIDB").

            10.12.3  Telephone Assistance Program.  Upon conversion to Focal's
                     ----------------------------
Resale Service of an existing Telecommunications Assistance Program Customer, no
exchange of qualification documentation is necessary. Ameritech will continue to
administer the Telecommunications Assistance Program for the Customer on behalf
of Focal. If Focal's Customer is newly qualified for a Telecommunications
Assistance Program, Focal must send Ameritech the necessary qualification
documentation.

            10.12.4  9-1-1 Services. Ameritech shall provide to Focal, for Focal
                     --------------                                           
Customers, 9-1-1 call routing to the appropriate PSAP. Ameritech shall provide
and validate Focal Customer information to the PSAP. Ameritech shall use its
service order process to update and maintain, on the same schedule that it uses
for its retail Customers, the Focal Customer service information in the ALI/DMS
(Automatic Location Identification/Data Management System) used to support 9-1-1
services.

            10.12.5  Special Services. If Ameritech makes a notation on the
                     ----------------                                    
Customer Service Records (CSR) of Customers who qualify for certain services
available to physically challenged individuals (e.g., special discounts)
                                                ----
("SPECIAL SERVICES"), Ameritech shall provide such data to Focal on the CSR made
available to Ameritech for its Customers. For usage by an Focal Customer of a
Telephone Relay Service, Ameritech will provide Focal with all billing
information furnished to Ameritech by the provider of the Telephone Relay
Service.

            10.12.6  Law Enforcement Interfaces. Interfaces with law enforcement
                     --------------------------                               
agencies and other security matters shall be conducted as specified in SCHEDULE
                                                                       --------
10.12.6.
-------

     10.13  SERVICE FUNCTIONS.

            10.13.1  Point of Contact for Resale Purchase Customer.

            (a)  Primary Point of Contact. Except as otherwise provided in this
                 ------------------------                                    
                 Agreement, Focal shall be the primary point of contact for all
                 Focal Customers.

            (b)  Service Referrals. Ameritech shall refer all questions
                 -----------------                                   
                 regarding any Focal service or product directly to Focal in
                 accordance with the procedures set forth in the Implementation
                 Plan. Ameritech shall use its best efforts to

                                      43
<PAGE>
 
               ensure that all Ameritech representatives who receive inquiries
               regarding Focal services do not in any way disparage or
               discriminate against Focal or its products or services.

          (c)  Customer Contact Employee Training. Ameritech shall provide
               ----------------------------------                       
               training for all its employees who may communicate, either by
               telephone or face-to-face, with Focal Customers to assure that
               the requirements of this Agreement are met. Furthermore, the same
               quality standards that Ameritech requires of its employees when
               contacting an Ameritech Customer (e.g., honesty, respect and
                                                 ---
               courtesy) shall apply when its employees are in contact with
               Focal Customers.

          10.13.2  Operations Support Systems Functions--Provisioning.

          (a)  Electronic Interface for Pre-Ordering, Ordering and Provisioning.
               ----------------------------------------------------------------
               Ameritech will provide an electronic interface for the transfer
               and receipt of data necessary to perform each of the pre-ordering
               ordering, and provisioning functions (e.g., order entry,
                                                     -----
               telephone number selection, and due date selection) associated
               with Resale Services. Initially, the interface for ordering will
               be separate from the interface used for pre-ordering and
               provisioning. By the end of the first quarter of 1997,the
               interface for ordering will migrate to the pre-ordering and
               provisioning interface. The interface will be administered
               through a gateway that will serve as a single point of contact
               for the transmission of such data. The interface will be
               consistent with the Alliance for Telecommunications Industry
               Solutions (ATIS), Telecommunications Industry Forum (TCIF),
               Electronic Data Interchange (EDI) Customer Service Guideline,
               issue 5, and provide the functionality described in SCHEDULE
                                                                   --------
               10.13.2 and Ameritech's Service Order Interface Document, version
               -------
               2.00. The electronic interface to be provided by Ameritech will
               provide system to system communications on a real-time basis
               (response in seconds), with built-in error recovery and built in
               operations, administration and maintenance functionality, at a
               ninety-five percent (95%) network reliability level. However, as
               an industry standard interface is developed by the appropriate
               industry forum, and generally accepted for implementation by the
               industry, Ameritech shall implement such interface.

          (b)  Service Ordering and Provisioning. Service Orders will be placed
               ---------------------------------
               by Focal and provisioned by Ameritech in accordance with the
               procedures described in SECTION 10.7. Any Service Order activity
                                       ------------
               resulting in primary local exchange carrier changes will comply
               with the requirements of 47 C.F.R. (S) 64.1100 and SECTION
                                                                  -------
               10.9.1.
               ------

                                      44
<PAGE>
 
          (c)  Provisioning Support. Ameritech shall provide provisioning
               --------------------
               support to Focal on the same basis Ameritech provides to its
               retail Customers. Provisioning support may be expanded as
               mutually agreed by the Parties.
 
          (d)  Status Reports. After receipt and acceptance of a Service Order,
               --------------
               Ameritech shall provide Focal with service status notices on an
               exception basis.
 
          (e)  Engineering Support. When requested by Focal, Ameritech shall
               -------------------
               provide timely engineering support.

          (f)  Requests for Service Changes. Where Ameritech provides
               ----------------------------                         
               installation, Ameritech's representatives shall inform an Focal
               Customer to contact Focal if such Customer requests a service
               change at the time of installation.

          (g)  Non-Interruption of Service. Except as specifically provided in
               ---------------------------
               this Agreement or pursuant to an order of a court or commission
               of competent jurisdiction, Ameritech may not initiate any
               disconnect, suspension or termination of an Focal Customer's
               Resale Service, unless directed to do so by Focal by transmission
               of a Service Order or Ameritech's receipt of proper authorization
               to change such Customer's primary local exchange carrier to a
               carrier other than Focal.

          10.13.3  Operations Support Systems Functions -- Maintenance.

          (a)  Electronic Interface for Maintenance and Repair. Ameritech will
               -----------------------------------------------              
               provide an electronic interface for the transfer and receipt of
               data necessary to perform the maintenance and repair functions
               (e.g., trouble receipt and trouble status). This interface will
                ----
               be administered through a gateway that will serve as a single
               point of contact for the transmission of such data. The interface
               will be consistent with the Alliance for Telecommunications
               Industry Solutions (ATIS), TI - Telecommunications (TI) -
               Operations, Administration, Maintenance and Provisioning (OAM&P),
               standard TI.227-95 and TI.228-95 and the Ameritech Electronic
               Bonding Interface (EBI) document. However, as an industry
               standard interface is developed by the appropriate industry
               forum, and generally accepted for implementation by the industry,
               Ameritech shall implement such interface.

          (b)  Maintenance. Maintenance will be provided by Ameritech as set
               -----------
               forth in the Implementation Plan and in accordance with the
               requirements set forth in SECTIONS 10.7 and 10.8 and SCHEDULE
                                         -------------     ----     --------
               10.13.
               -----

                                      45
<PAGE>
 
     10.14  RESPONSIBILITIES OF FOCAL.

            10.14.1  Focal shall be responsible for providing to its Customers
and to Ameritech a telephone number or numbers that Focal's Customers can use to
contact Focal in the event of service or repair requests. If Focal's Customers
contact Ameritech with regard to such requests, Ameritech shall inform such
Customers that they should call Focal and will provide Focal's contact numbers
to such Customers. At Focal's request, Ameritech shall provide a "warm" transfer
to Focal of calls it receives from Focal's Customers for service or repair
requests at the rates set forth at Item VI of the Pricing Schedule.

            10.14.2  Focal shall provide Ameritech with accurate and complete
information regarding Focal's Customers in a method reasonably prescribed by
Ameritech to allow Ameritech to keep its Emergency Telephone Number Service
database updated, if Ameritech maintains such a database.

            10.14.3  Prior to the Effective Date,/10/ Focal shall have received
and communicated to Ameritech its Carrier Identification Code and its Access
Carrier Name Abbreviation or Interexchange Access Customer Code.

     10.15  RESPONSIBILITIES OF AMERITECH.

     Ameritech shall provide access to the following services where Ameritech is
the underlying 9-1-1 service provider:

            (i)   Universal Emergency Number service, a telephone exchange
                  communication service which includes lines and equipment
                  necessary for answering, transferring and dispatching public
                  emergency telephone calls originated by persons within the
                  telephone Central Office areas arranged for 9-1-1 calling.

            (ii)  Basic 9-1-1 service (where available) provides for routing all
                  9-1-1 calls originated by Customers having telephone numbers
                  beginning with a given Central Office prefix code or codes to
                  a single PSAP equipped to receive those calls.

            (iii) Enhanced 9-1-1 ("E9-1-1) service, which provides additional
                  features to Basic 9-1-1 service, such as selective routing of
                  9-1-1 calls to a specific PSAP which is selected from the
                  various PSAPs serving Customers within that Central Office
                  area.

________________
/10/  Since the terms of this Agreement are the result of Focal's adoption under
      Section 252(i) of the Act of the Teligent Agreement, the Parties agree
      that the term "Effective Date", for purposes of this SECTION 10.14.3,
                                                           --------------- 
      shall mean February 10, 1999.

                                      46
<PAGE>
 
Both Focal and its Customers purchasing Resale Service under this Agreement are
not charged for calls to the 9-1-1 number, except as provided in any applicable
tariff or pursuant to Applicable Law.

     10.16  EXCHANGE OF BILLING INFORMATION.

            10.16.1  Ameritech shall provide Focal a specific Daily Usage File
("DUF") for Resale Services provided hereunder ("CUSTOMER USAGE DATA"). Such
Customer Usage Data shall be recorded by Ameritech in accordance with the
Ameritech Electronic Billing System (AEBS) and EMR. The DUT shall include
specific daily usage, including both Local Traffic and IntraLATA Toll Traffic,
in EMR format, for each individual Resale Service and shall include sufficient
detail to enable Focal to bill its Customers for Resale Services provided by
Ameritech. Ameritech will provide to Focal detailed specifications which will
enable Focal to develop an interface for the exchange of Customer Usage Data.
Procedures and processes for implementing the interface will be included in the
Implementation Plan. Except as provided in SECTION 10.16.4, no other detailed
                                           ---------------
billing shall be provided by Ameritech to Focal.

            10.16.2  Interexchange call detail forwarded to Ameritech for
billing, which would otherwise be processed by Ameritech, will be returned to
the IXC and will not be passed through to Focal. This call detail will be
returned to the IXC with a transaction code indicating that the returned call
originated from a resold account. Billing for 900 and 976 calls or other
Information Services Traffic will be passed through when Ameritech records the
message. If Focal does not wish to be responsible for 900 and 976 calls, it must
order blocking for resold lines. When the IXC records the 900 and 976 calls, the
call detail will be returned to the IXC. Upon Focal's request, Ameritech will
recourse charges on 900 and 976 calls to the Information Service provider in
accordance with existing agreements with such providers. If the provider will
not accept recourse, Ameritech will notify Focal, and Focal, at its option and
expense, may pursue any rights which Ameritech may have under such agreements to
contest such charge. If Focal elects not to contest such charges or such
Information Service provider does not accept the recourse, Focal will promptly
pay Ameritech for such charges and the dispute shall be solely between Focal and
the Information Service provider.

            10.16.3  Focal shall be responsible for providing all billing
information to its Customers who purchase Resale Services from Focal.

            10.16.4  Ameritech shall bill Focal for Resale Services provided by
Ameritech to Focal pursuant to the provisions of ARTICLE XXVII. Ameritech shall
                                                 -------------
recognize Focal as the Customer of Record for all Resale Services and will send
all notices, bills and other pertinent information directly to Focal. The bill
will include sufficient data to enable Focal to (i) bill all charges to its
Customers which are not included as Customer Usage Data and (ii) reconcile the
billed charges with the Customer Usage Data.

                                      47
<PAGE>
 
     10.17  USE OF SERVICE.

            10.17.1  Focal, and not Ameritech, shall be responsible to ensure
that its and its Customers' use of the Resale Services comply at all times with
Applicable Law. Ameritech may refuse to furnish or may disconnect Resale
Services of Focal or, as appropriate to Focal's Customer, when:

            (a)   An order is issued by a court, the Commission or any other
                  duly authorized agency, finding that probable cause exists to
                  believe that the use made or to be made of a Resale Service is
                  prohibited by Applicable Law, or

            (b)   Ameritech is notified in writing by a law enforcement agency
                  acting within its jurisdiction that any facility furnished by
                  Ameritech is being used or will be used for the purpose of
                  transmitting or receiving gambling information in interstate
                  or foreign commerce in violation of law.

The provisions described in this SECTION 10.17.1 shall apply only to the
                                 ---------------
specific affected Resale Services.

            10.17.2  Termination of Resale Service shall take place after
reasonable notice is provided to Focal, or as ordered by a court.

            10.17.3  To the extent provided under the Telephone Consumer
Protection Act (47 U.S.C. (S) 227) and regulations thereunder. Resale Service
shall not be used for the purpose of solicitation by recorded message when such
solicitation occurs as a result of unrequested calls initiated by the solicitor
by means of automatic dialing devices. Such devices, with storage capability of
numbers to be called or a random or sequential number generator that produces
numbers to be called and having the capability, working alone or in conjunction
with other equipment, of disseminating a prerecorded message to the number
called and which are calling party or called party controlled, are expressly
prohibited.

            10.17.4  The Resale Services shall not be used in any manner that
interferes with other persons in the use of their Telecommunications Service,
prevents other persons from using their Telecommunications Services, or
otherwise impairs the quality of service to other carriers or Ameritech's
Customers.

            10.17.5  If Focal's use of Resale Services interferes unreasonably
with the Resale Services of other carriers or their customers or Ameritech or
Focal's Customers, Focal shall be required to take Resale Services in sufficient
quantity or of a different class or grade to correct such interference.

                                      48
<PAGE>
 
                                  ARTICLE XI
                    NOTICE OF CHANGES -- SECTION 251(C)(5)
                                        
     If a Party makes (i) a change in its network which will materially affect
the interoperability of its network with the other Party or (ii) changes
Operations Support Systems functions which affect the operations of the other
Party, the Party making the change shall provide reasonable advance written
notice of such change to the other Party within such time period as determined
by the FCC or the Commission and their respective rules and regulations.

                                  ARTICLE XII
                       COLLOCATION -- SECTION 251(C)(6)
                                        
     12.1  PHYSICAL COLLOCATION.

Ameritech shall provide to Focal Physical Collocation on its Premises for
equipment necessary for Interconnection (pursuant to ARTICLE III) or for access
                                                     -----------
to unbundled Network Elements (pursuant to ARTICLE IX), except that Ameritech
                                           ----------
will provide for Virtual Collocation of such equipment if Ameritech demonstrates
to the Commission that Physical Collocation is not practical for technical
reasons or because of space limitations, as provided in Section 2.51 (c)(6) of
the Act. Ameritech shall provide Focal Collocation only for the purpose of
Interconnection or access to Ameritech's Network Elements.

     12.2  VIRTUAL COLLOCATION IN PHYSICAL COLLOCATION SPACE. Where Focal is
Virtually Collocated on the Effective Date in a space that was initially
prepared for Physical Collocation, Focal may elect to (i) retain its Virtual
Collocation on that Premises and expand that Virtual Collocation according to
current procedures and applicable tariffs or (ii) revert to Physical
Collocation, in which case Focal shall coordinate with Ameritech for
rearrangement of its transmission equipment and facilities, for which Ameritech
shall impose no conversion charge. All applicable Physical Collocation recurring
charges shall apply.

     12.3  VIRTUAL COLLOCATION IN VIRTUAL COLLOCATION SPACE. Where Focal is
Virtually Collocated in a space which was initially prepared for Virtual
Collocation, Focal may elect to (i) retain its Virtual Collocation in that space
and expand that Virtual Collocation according to current procedures and the
terms and conditions of this Agreement or (ii) unless it is not practical for
technical reasons or because of space limitations, convert its Virtual
Collocation to Physical Collocation at such Premises, in which case Focal shall
coordinate the construction and rearrangement with Ameritech of its transmission
equipment and facilities for which Focal shall pay Ameritech at the rates set
forth at Item VII of the Pricing Schedule. In addition, all applicable Physical
Collocation recurring charges shall apply.

                                      49
<PAGE>
 
     12.4  NONDISCRIMINATORY COLLOCATION.

           Collocation shall be made available to Focal by Ameritech on a basis
that is at parity to the priorities that Ameritech provides to itself, its
subsidiaries, Affiliates or other persons. The quality of design, performance,
features, functions and other characteristics of Collocation made available to
Focal under this Agreement shall be at parity to that which Ameritech provides
in its network to itself, its subsidiaries, its Affiliates or other persons.

     12.5  ELIGIBLE EQUIPMENT.

Focal may Collocate equipment necessary for Interconnection, or access to
Ameritech's  Network Elements including the following types of equipment:

           (a)  OLTM equipment;

           (b)  multiplexers;

           (c)  Digital Cross-Connect Panels;

           (d)  Optical Cross-Connect Panels;

           (e)  Digital Loop Carrier (utilizing transmission capabilities only);

           (f)  Data voice equipment, and

           (g)  any other transmission equipment collocated as of August 1, 1996
                necessary to terminate basic transmission facilities pursuant to
                47 C.F.R. (S)(S) 64.1401 and 64.1402.

Focal may Collocate equipment necessary for Interconnection or access to
unbundled Network Elements, which shall include equipment used for signal
regeneration (or "hubbing"). Additionally, Focal shall be permitted to collocate
for any purpose, or in any manner or method authorized by the Act, the
Commission or the FCC.

     12.6  TRANSMISSION FACILITY OPTIONS. For both Physical Collocation and 
Virtual Collocation, Focal may either purchase unbundled transmission facilities
(and any necessary Cross-Connection) from Ameritech or provide its own or third-
party leased transmission facilities and terminate those transmission facilities
in its equipment located in its Collocation space at Ameritech's Premises.

     12.7  INTERCONNECTION WITH OTHER COLLOCATED CARRIERS.

Upon written request to Ameritech, Focal shall be permitted to Interconnect its
network with that of another collocating Telecommunications Carrier at
Ameritech's Premises by connecting its

                                      50
<PAGE>
 
collocated equipment to the collocated equipment of the other Telecommunications
Carrier via a Cross-Connection or other connecting transmission facilities so
long as (i) Focal's and the other collocating Telecommunications Carrier's
collocated equipment are both used for Interconnection with Ameritech or for
access to Ameritech's Network Elements, (ii) Focal provides the connection
between the equipment in the collocated spaces via a Cross-Connection or other
connecting transmission facility that, at a minimum, complies in all respects
with Ameritech's technical and engineering requirements and (iii) the
connecting transmission facilities of Focal and the other collocating
Telecommunications Carrier are contained wholly within space provided solely for
Physical Collocation within Ameritech's Premises. If Focal Interconnects its
network with another collocating Telecommunications Carrier pursuant to this
SECTION 12.7, Focal shall, in addition to its indemnity obligations set forth in
------------
ARTICLE XXV, indemnify Ameritech for any Loss arising from Focal's installation,
-----------
use, maintenance or removal of such connection with the other collocated
Telecommunications Carrier, to the extent caused by the actions or inactions of
Focal.

     12.8  INTERCONNECTION POINTS AND CABLES.

Ameritech shall:

           12.8.1  provide Focal an Interconnection point or points physically
accessible by both Ameritech and Focal, at which the fiber optic cable carrying
Focal's circuits can enter Ameritech's Premises; provided that Ameritech shall
                                                 --------                    
designate Interconnection Points as close as reasonably possible to Ameritech's
Premises;

           12.8.2  provide at least two (2) such Interconnection points at
Ameritech's Premises at which there are at least two (2) entry points for
Focal's cable facilities, and at which space is available for new facilities in
at least two (2) of those entry points;

           12.8.3  permit Focal Interconnection of copper or coaxial cable if
such Interconnection is first approved by the Commission; and

           12.8.4  permit Focal Physical Collocation of microwave transmission
facilities, except where such Collocation is not practical for technical reasons
or because of space limitations, in which case Ameritech shall provide Virtual
Collocation of such facilities as required where technically feasible.

     12.9  ALLOCATION OF COLLOCATION SPACE.

           12.9.1  Focal may reserve Collocation space for its future use in
Ameritech's Premises in accordance with the provisions of SCHEDULE 12.9.1.
                                                          ---------------
Ameritech shall notify Focal in writing if another Telecommunications Carrier
requests Collocation space that is reserved by Focal. Focal shall within five
(5) Business Days of receipt of such notice provide Ameritech either (i) written
notice that Focal relinquishes such space or (ii) enforce its reservation of
space in accordance with the provisions of SCHEDULE 12.9.1. Failure of Focal to
                                           ---------------
respond to Ameritech within the foregoing five (5) Business Day period shall be
deemed an election by Focal to relinquish such space.

                                      51
<PAGE>
 
            12.9.2  Ameritech shall not be required to lease or construct
additional space in a Premises to provide Focal Physical Collocation when
existing space in such Premises has been exhausted.

            12.9.3  Focal will provide Ameritech with a two (2)-year rolling
forecast of its requirements for Collocation that will be reviewed jointly on a
yearly basis by the Parties, in accordance with the planning processes described
in SCHEDULE 12.9.3. Ameritech will attempt to deliver Collocation pursuant to
   ---------------                                                         
Focal's forecasts to the extent that Collocation space is then available.

     12.10  SECURITY ARRANGEMENTS. Focal shall adopt, at the request of
Ameritech and at Focal's sole cost and expense, reasonable security arrangements
as designated by Ameritech to separate Focal's Collocation space from
Ameritech's facilities, including the construction of a collocation cage.

     12.11  SUBCONTRACTOR AND VENDOR APPROVAL. Ameritech shall permit Focal to
subcontract the construction and build-out of Physical Collocation arrangements
with contractors approved by Ameritech. Approval of such subcontractors by
Ameritech shall be based on the same criteria it uses in approving contractors
for its own purposes. In addition, Ameritech shall allow Focal to have an
Ameritech-approved vendor install updates to collocated equipment, including
software updates.

     12.12  DELIVERY OF COLLOCATED SPACE.

            12.12.1  Ameritech shall provide Focal with a single point of
contact for all inquiries regarding Collocation. Focal shall request space for
Collocation by delivering a written request to Ameritech. Each request for
Collocation shall include (i) the Premises in which Collocation is requested,
(ii) the amount of space requested, (iii) the interoffice transmission
facilities Focal will require for such space, (iv) the equipment to be housed in
such space, (v) Focal's anticipated power requirements for the space, (vi) 
any extraordinary additions or modifications (i.e., security devices, node
                                              ----
enclosures, HVAC, etc.) to the space or to the Premises to accommodate Focal's
collocated equipment, (vii) the specific level of diversity for fiber and power
cabling to and from the Collocated space and (viii) the date on which Focal
intends to initiate service from such space. Ameritech shall notify Focal in
writing within ten (10) Business Days of receiving Focal's request for
Collocation as to whether the requested space is available. If space is not
available for Physical Collocation, Ameritech shall specify in its notice to
Focal when space for Physical Collocation will be made available to Focal and
shall offer to Focal Virtual Collocation Space in accordance with SECTION
                                                                  -------  
12.12.3. If intraoffice facilities will not be available for Collocation of
-------
initial service within three (3) months of receipt of Focal's payment of the
Initial COBO fee for Physical Collocation, or twelve (12) weeks after receipt of
Focal's request for Virtual Collocation pursuant to SECTION 12.12.1, then
                                                    ---------------
Ameritech shall provide written notification, within ten (10) Business Days
after the initial walkthrough, as to when the intraoffice facilities will be
made available.

                                      52
<PAGE>
 
          12.12.2  Physical Collocation.

          (a)  If space for Physical Collocation is immediately available at the
               time of Focal's request, Ameritech shall include in its notice to
               Focal (i) the space to be provided and (ii) whether Ameritech can
               deliver the space to Focal by the date set forth in SECTION
                                                                   -------
               12.12.2 (C).
               -----------

          (b)  If Focal's requested Physical Collocation space is available,
               Ameritech and Focal shall have an initial walkthrough of such
               space within ten (10) Business Days after Ameritech's receipt of
               Focal's Initial COBO Payment. Ameritech shall, within ten (10)
               Business Days after such initial walkthrough, provide
               documentation submitted to and received from contractors for any
               work being done on behalf of Focal that will be billed as
               extraordinary expenses and provide for a parallel installation
               sequence.

          (c)  Ameritech shall deliver to Focal the requested space on or before
               the later of (i) one hundred twenty (120) days from Ameritech's
               receipt of Focal's request for Collocation, (ii) ninety (90) 
               days from the receipt of Focal's Initial COBO Payment (as
               provided on SCHEDULE 12.12) and (iii) such other reasonable date
                           --------------                   
               that the Parties may agree upon if it is not feasible for
               Ameritech to deliver to Focal such space within the foregoing
               intervals (such date of delivery referred to as the "DELIVERY 
               DATE").

          (d)  Physical Collocation space ordered by Focal will be made
               available to Focal by Ameritech as more fully described in
               SECTION 1 OF SCHEDULE 12.12.
               ---------    --------------

          (e)  If Ameritech does not provide Focal with its Collocated space by
               the Delivery Date and such delay is caused directly by
               Ameritech's actions or its failure to act (and not by an Focal
               Delaying Event), Focal shall receive a credit of 1/120th of its
               COBO payment for each day after the applicable Delivery Date that
               such Collocated space is not made available.

          (f)  Ameritech may begin billing Focal for recurring charges for the
               Collocated space on the date such space is made available to
               Focal for occupancy (the "OCCUPANCY DATE"). Focal shall vacate
               the Collocated space if either (i) Focal fails to install within
               ninety (90) days of the Occupancy Date the equipment necessary
               to Interconnection and/or access to unbundled Network Elements
               to be housed in such space or (ii) Focal fails to Interconnect to
               the Ameritech network within one hundred eighty (180) days of the
               Occupancy Date or such other negotiated time as may be mutually
               agreed upon by the Parties. If Focal is required to vacate the
               space pursuant to this SECTION 12.12.2(F), Focal shall vacate
                                      ------------------  
               such space within ninety (90) Business Days of the earliest to
               occur of the foregoing events. If, after vacating a space, Focal
               still requires Collocation in that Premises, Focal shall

                                      53
<PAGE>
 
               be required to submit a new request for Collocation pursuant to
               the provisions of SECTION 12.12.1.
                                 ---------------

          (g)  Physical Collocation will be subject to the additional rules and
               regulations set forth in SECTION 2.0 OF SCHEDULE 12.12, and Focal
                                        -----------    --------------   
               shall pay all costs to provide such Collocation.

          (h)  Ameritech shall provide positive confirmation to Focal when
               construction of Focal Collocated space is fifty percent (50%)
               completed. This confirmation shall also include confirmation of
               the scheduled completion date and Delivery Date. The
               Implementation Plan will include a process for determining when
               construction is fifty percent (50%) complete.

          (i)  At Focal's request Ameritech shall provide, within three (3)
               months after receiving Focal's Initial COBO Payment, equipment
               node enclosures at a height of eight (8) feet, without ceiling.
               Where Ameritech cannot feasibly provide Focal with equipment node
               enclosures within such three (3) month period, Ameritech shall
               notify Focal of this fact within ten (10) Business Days from the
               initial walkthrough. The Parties shall then negotiate a
               reasonable time frame.

          (j)  After completion of construction, Focal and Ameritech will
               complete an acceptance walkthrough of all Collocated space
               requested from Ameritech. Exceptions that are noted during this
               acceptance walkthrough shall be corrected by Ameritech within
               thirty (30) days after the walkthrough. Ameritech shall conduct a
               root cause analysis of all exceptions identified. The correction
               of these exceptions from Focal's original request for Collocation
               shall be at Ameritech's expense, subject to any change orders
               requested by Focal.

          12.12.3  Virtual Collocation.

          (a)  If Focal requests Virtual Collocation, or if requested Physical
               Collocation space is not available at a Premises and Focal elects
               Virtual Collocation, and such Virtual Collocation is available at
               the time of Focal's request, Ameritech shall include in its
               notice to Focal described in Section 12.12.1(i) the space to be
                                                    ------- 
               provided and (ii) whether Ameritech can deliver the space to
               Focal by the date set forth in SECTION 12.12.3(C).
                                              ------------------

          (b)  Ameritech and Focal will have an initial walkthrough of the
               Collocated space to be provided to Focal for Virtual Collocation
               on the earlier of (i) ten (10) Business Days of Ameritech's
               verification of the Virtual Collocation space to be provided to
               Focal and (ii) ten (10) Business Days after Ameritech's receipt
               of Focal's request for Virtual Collocation. Ameritech shall
               within ten

                                      54
<PAGE>
 
               (10) Business Days after such walkthrough provide Focal with
               (i) documentation submitted to and received from contractors for
               any work being done on behalf of Focal that will be billed as
               extraordinary expenses and (ii) a parallel installation sequence.

          (c)  Ameritech shall deliver to Focal the requested space on or before
               the later of (i) twelve (12) weeks from Ameritech's receipt of
               Focal's request for Virtual Collocation and (ii) such other
               reasonable date that the Parties may agree upon if it is not
               feasible for Ameritech to deliver to Focal such space within
               twelve (12) weeks (such date of delivery referred to as the
               "DELIVERY DATE") and Ameritech notified Focal of this fact within
               ten (10) Business Days from the initial walkthrough.

          (d)  Virtual Collocation space ordered by Focal will be made available
               to Focal by Ameritech, as more fully described in SECTION 3 of
                                                                 ---------   
               SCHEDULE 12.12.
               --------------
                
          (e)  Ameritech shall provide positive confirmation to Focal when
               construction of Focal-collocated space is fifty percent (50%)
               completed. This confirmation shall also include confirmation of
               the scheduled completion date and the Delivery Date. The
               Implementation Plan will include a process for determining when
               construction is fifty percent (50%) complete.

          (f)  After completion of construction, Focal and Ameritech will
               complete an acceptance walkthrough of all collocated space
               requested from Ameritech. Exceptions that are noted during this
               acceptance walkthrough shall be corrected by Ameritech within
               thirty (30) days after the walkthrough. Ameritech shall conduct a
               root cause analysis of all exceptions identified. The correction
               of these exceptions from the original request for Collocation
               shall be at Ameritech's expense, subject to any change orders
               requested by Focal.

          (g)  Ameritech shall install cross-connects when cross-connecting for
               thru connect purposes as directed by Focal at the rates provided
               at Item VII of the Pricing Schedule.

    12.13 PRICING. The prices charged to Focal for Collocation are set forth at
Item VII of the Pricing Schedule.

    12.14 BILLING. Ameritech shall bill Focal for Collocation pursuant to the
requirements of ARTICLE XXVII to this Agreement.
                -------------

    12.15 COMMON REQUIREMENTS. The requirements set forth on SCHEDULE 12.15
                                                             --------------     
shall be applicable to both Physical and Virtual Collocation.

                                      55
<PAGE>
 
     12.16  ADDITIONAL REQUIREMENTS. The additional requirements set forth on
SCHEDULE 12.16 shall be applicable to Physical Collocation.
--------------                                            

     12.17  PROTECTION OF SERVICE AND PROPERTY.

            Both Parties shall exercise reasonable care to prevent harm or
damage to the other Party, its employees, agents or Customers, or their
property. Both Parties, their employees, agents, and representatives agree to
take reasonable and prudent steps to ensure the adequate protection of the other
Party's property and services, including:

            12.17.1  Ameritech and Focal shall restrict access to Focal
equipment, support equipment, systems, tools and data, or spaces which contain
or house Focal equipment enclosures, to Focal employees and other authorized 
non-Focal personnel to the extent necessary to perform their specific job
function.

            12.17.2  Focal shall comply at all times with security and safety
procedures and existing, requirements that are defined by Ameritech and
communicated to Focal.

            12.17.3  Ameritech shall allow Focal periodically to inspect or
observe spaces which house or contain Focal equipment or equipment enclosures
and furnish Focal with keys, entry codes, lock combinations, and other materials
or information which may be needed to gain entry into any secured Focal space,
subject to SECTION 12.17.2 and ARTICLE XX and, in the case of Virtual 
           ---------------     ----------
Collocation, payment by Focal of the cost of Ameritech escorts.

            12.17.4  For Physical Collocation, Ameritech shall furnish to Focal
a current written list of Ameritech's employees who Ameritech authorizes to
enter Focal's Physical Collocation space, with samples of the identify 
credential to be carried by such persons.

            12.17.5  Ameritech shall secure external access to the Physical
Collocation space on its Premises in the same or equivalent manner that
Ameritech secures external access to spaces that house Ameritech's equipment.

            12.17.6  For Physical Collocation, Ameritech shall limit the keys
used in its keying equipment or systems for Focal's specific Physical
Collocation space which contain or house Focal equipment or equipment enclosures
to its employees and representatives to emergency access only. Focal shall
further have the right, at its expense, to have locks changed where deemed
necessary for the protection and security of such spaces, provided that Focal
                                                          --------  
shall immediately provide Ameritech with such new keys.

            12.17.7  Ameritech shall use its existing back-up and recovery plan
in accordance with its standard policies for the specific Central Office.

     12.18  STANDARDS OF PERFORMANCE.

                                      56
<PAGE>
 
Ameritech shall provide Collocation to Focal in accordance with the service
levels, procedures and intervals, if any, agreed upon by the Implementation Team
as provided in SECTION 18.6.
               ------------

                                 ARTICLE XIII
                   NUMBER PORTABILITY -- SECTION 251(B)(2).
                                        
     13.1  PROVISION OF LOCAL NUMBER PORTABILITY.

Each Party shall provide to the other Party, to the extent technically feasible,
Local Number Portability in accordance with the requirements of the Act. To the
extent technically feasible, Local Number Portability will be provided by, each
Party with minimum impairment of functionality, quality, reliability and
convenience to subscribers of the other Party's services.

     13.2  INTERIM NUMBER PORTABILITY ("INP").

The Parties agree to provide INP on a reciprocal basis between their networks to
enable their Customers to utilize telephone numbers associated with a Telephone
Exchange Service provided by one Party, in conjunction with a Telephone Exchange
Service provided by the other Party, upon the coordinated or simultaneous
termination of the first Telephone Exchange Service and activation of the second
Telephone Exchange Service. The Parties shall provide reciprocal INP via remote
call forwarding ("RCF"), Direct Inward Dialing ("DID") or through NXX
Migration; provided, in each case that the Customer whose telephone number is
           --------
subject to INP remains within the same serving Wire Center.

     13.3  REMOTE CALL FORWARDING ("RCF").

           13.3.1  If a Telephone Exchange Service Customer of Party A elects to
become a Telephone Exchange Service Customer of Party B, such Customer may elect
to utilize the original telephone number(s) corresponding to the Telephone
Exchange Service(s) it previously received from Party A, in conjunction with the
Telephone Exchange Service(s) it shall now receive from Party B. Provided that
Party B has complied with the requirements of SECTION 10.11.1 and has issued an
                                              ---------------
associated service order to Party A to assign the number to Party B, Party A
shall implement an arrangement whereby all calls to the original telephone
number(s) shall be forwarded on a multiple-path basis to a new telephone
number(s) designated by Party B. Party A shall route the forwarded traffic to
Party B over the appropriate trunks as if the call were a call which had
originated on Party A's network.

           13.3.2  Party B shall become the Customer of Record for the original
Party A's telephone number(s), subject to the RCF or DID arrangements. Party A
shall use its reasonable efforts to provide Party B with a consolidated billing
statement for all collect and billed-to-

                                      57
<PAGE>
 
3rd-number calls associated with those numbers, with sub-account detail by
retained number. Such billing statement shall be delivered in a mutually agreed
format via either paper, electronic file transfer, daily magnetic tape or
monthly magnetic tape. Party A shall provide to Party B the Exchange Message
Record ("EMR") containing detailed records associated with the calls reflected
on the billing statement, as generated by the Ameritech Electronic Billing
System ("AEBS").

           13.3.3  Party A may cancel line-based calling cards and shall, as
directed by Party B, update its LIDB listing for retained numbers subject to
RCF or DID. Ameritech will include billing, number information associated with
numbers used for INP arrangements in its LIDB and will store and administer such
data in the same manner as Ameritech's data for its Customers. Ameritech shall
provide responses to on-line queries to the stored information for the purpose
of calling, card validation, fraud control and billed numbers screening without
charge.

           13.3.4  If a Customer elects to move its Telephone Exchange Service
back to Party A during the continuance of the RCF or DID arrangement, Party B
shall notify Party A of the Customer's termination of service with Party B and
the Customer's instructions regarding its telephone number(s) within two (2)
Business Days of receiving notification from the Customer. Subject to procedures
generally, performed by Party A for potential new Customers (e.g., credit
                                                             ----
checks, receipts of deposit), Party A shall reinstate service to the Customer,
cancel the RCF or DID arrangement, or redirect the RCF, or DID arrangement
pursuant to the Customer's instructions at that time.

           13.3.5  For ported numbers using RCF, Focal shall provide in the 
9-1-1 information Focal provides to Ameritech under this Agreement both the
ported number and Focal's RCF number if Focal has provided such RCF number to
Ameritech. Ameritech shall include such information, if provided by Focal, in
the PSAP database to the extent that the database is capable of storing both
numbers.

     13.4  DIRECT INWARD DIALING. DID service provides trunk-side access to End
Office Switches for direct inward dialing to the other Party's premises
equipment from the telecommunications network to lines associated with the other
Party's switching equipment and must be provided on all trunks in a group
arranged for inward service. In addition, direct facilities are required from
the End Office where a ported number resides to the End Office serving, the
ported Customer. Transport mileage will be calculated as the airline distance
between the End Office where the number is ported and the Interconnection Wire
Center using, the V&H coordinate method. INP-DID must be established with a
minimum configuration of two channels and one (1) unassigned telephone number
per switch, per arrangement for control purposes. Transport facilities arranged
for INP-DID may not be mixed with any other type of trunk group, with no
outgoing calls placed over said facilities. INP-DID will be provided only where
such facilities are available and where the switching equipment of the ordering,
Party is properly equipped. Where INP-DID service is required from more than one
(1) Wire Center or from separate trunk groups within the same Wire Center, such
service provided from each

                                      58
<PAGE>
 
Wire Center or each trunk group within the same Wire Center shall be considered
a separate service.

     13.5 NXX MIGRATION. Where a Party has activated an entire NXX for a single
Customer, or activated a substantial portion of an NXX for a single customer
with the remaining numbers in that NXX either reserved for future use or
otherwise unused, if such Customer chooses to receive service from the other
Party, the first Party shall cooperate with the second Party to have the entire
NXX reassigned (or subsequently reassigned, in the case of subsequent carrier
changes) in the LERG (and associated industry databases, routing tables, etc.)
to an End Office operated by the second Party. Such transfer will be
accomplished with appropriate coordination between the Parties and subject to
standard industry lead-times for movements of NXXs from one switch to another.
In the interim period, prior to the effective date of LERG reassignment, the
existing method of INP will be used.

     13.6  OTHER INTERIM NUMBER PORTABILITY PROVISIONS.

           13.6.1  Each Party shall disclose to the other Party, upon request,
any technical or capacity limitations that would prevent use of a requested
INP implementation in a particular switching office. Both Parties shall
cooperate in the process of porting numbers to minimize Customer out-of-service 
time.

           13.6.2  The Parties shall cooperate in conducting testing to ensure
interconnectivity between systems. Each Party shall inform the other Party of
any system updates that may affect the other Party's network and shall, at
mutually, agreeable times, perform tests to validate the operation of the
network. Additional testing requirements may apply as specified by this 
Agreement.

           13.6.3  Neither Party shall be required to provide Number Portability
for nongeographic services (e.g., 500 and 900 NPAs, 976 NXX number services and
                            ----  
coin telephone numbers) under this Agreement.

           13.6.4  Ameritech and Focal will cooperate to ensure that performance
of trunking and signaling capacity is engineered and managed at levels which are
at parity with that provided by Ameritech to its Customers.

     13.7  COMPENSATION ON TRAFFIC TO INP'ed NUMBERS. The Parties agree that,
under INP, transport and terminating compensation on calls to INP'ed numbers
should be received by each Customer's chosen LEC as if each call to the Customer
had been originally addressed by the caller to a telephone number bearing an 
NPA-NXX directly assigned to the Customer's chosen LEC. In order to accomplish
this objective where INP is employed, the Parties shall utilize the process set
forth in this SECTION 13.7. whereby transport and terminating compensation on 
              ------------                        
calls subject to INP will be passed from the Party (the "PERFORMING PARTY")
which performs the INP to the other Party (the "RECEIVING PARTY") for whose
Customer the INP is provided.

                                      59
<PAGE>
 
           13.7.1  The Parties shall individually and collectively track and
quantify INP traffic between their networks based on the CPN of each call by
identifying CPNs which are INP'ed numbers. The Receiving Party shall charge the
Performing Party for each minute of INP traffic at the INP Traffic Rate
specified in SECTION 13.7.3 in lieu of any other compensation charges for
             --------------  
terminating such traffic.

           13.7.2  By the Interconnection Activation Date in each LATA, the
Parties shall jointly estimate for the prospective year, based on historic data
of all traffic in the LATA, the percentages of such traffic that, if dialed to
telephone numbers bearing, NPA-NXXs directly assigned to a Receiving Party (as
opposed to the INP'ed number), would have been subject to (i) Reciprocal
Compensation ("RECIP TRAFFIC"), (ii) intrastate FGD charges ("INTRA TRAFFIC"),
or (iii) interstate FGD charges ("INTER TRAFFIC"). On the date which is six (6)
months after the Interconnection Activation Date, and thereafter on each
succeeding six (6)-month anniversary of such Interconnection Activation Date,
the Parties shall establish new INP traffic percentages to be applied in the
prospective six (6)-month period, based on actual INP traffic percentages from
the preceding six (6)-month period. The Parties may agree to adopt a different
methodology to calculate INP traffic percentages, including identifying
components different from or in addition to those set forth in this SECTION
                                                                    -------
13.7.2.
------

           13.7.3  The INP Traffic Rate shall be equal to the sum of:

           (Recip Traffic percentage times the Reciprocal Compensation Rate set
                                     -----
forth at Item II of the Pricing Schedule) plus (Intra Traffic percentage times
                                          ----                           -----  
the Receiving Party's effective intrastate FGD rates) plus (Inter Traffic
                                                      ----
percentage times the Receiving Party's effective interstate FGD rates) .
           -----

           Interstate and intrastate FGD rates shall be calculated utilizing the
effective interstate and intrastate carrier common line (CCL) rates, residual
interconnection charge (RIC) rate elements, local switching (LS) rate elements,
one-half the local transport termination (LTT) rate elements, and one-half the
local transport facility (LTF) rate elements (assuming a five (5)mile LTF).

     13.8  PRICING FOR INTERIM NUMBER PORTABILITY. Each Party shall comply with
the methodoloy (including recordkeeping) established by the FCC or the
Commission with respect to such Party's recovery in a competitively neutral
manner of its costs to provide Interim Number Portability. To the extent
permitted by the FCC or the Commission, such costs shall include a Party's costs
to deliver calls between the other Party's Customers via Number Portability.
Until such time as the Commission establishes such methodology, the Parties
shall bill each other for INP consistent with existing tariffs and Commission
orders.

     13.9  PERMANENT NUMBER PORTABILITY. The Parties shall migrate from RCF or
DID to Permanent Number Portability as soon as practically possible but no later
than the date provided for by the FCC. The Parties shall provide Permanent
Number Portability on a reciprocal basis to

                                      60
<PAGE>
 
each other in accordance with rules and regulations as from time to time
prescribed by the FCC and/or the Commission.

     13.10  OTHER INP METHODS.

Other methods of providing INP, to the extent technically feasible, may be
provided pursuant to a Bona Fide Request.

                                  ARTICLE XIV
             DIALING PARITY -- SECTIONS 251(B)(3) AND 271(E)(2)(B)
                                        
     The Parties shall provide Dialing Parity to each other as required under
Section 25 1 (b)(3) of the Act, except as may be limited by Section 271(e)(2)(B)
of the Act.

                                  ARTICLE XV
                    DIRECTORY LISTINGS -- SECTION 251(B)(3)
                                        
     15.1  DIRECTORY LISTINGS. Ameritech shall cause the Publisher to include
Primary Listings of Focal's Customers ("FOCAL DIRECTORY CUSTOMERS") in its
White Pages Directories under the following terms and conditions:

           15.1.1  Publisher will publish the Primary Listing of Focal Directory
Customers located within the geographic scope of Publisher's directories at no
charge.

           15.1.2  Listing of such Focal Directory Customers will be interfiled
with listings of subscribers of Ameritech and other LECs serving the same
geographic area where such listings are included within a directory.

           15.1.3  Publisher shall provide Focal with a copy of such listings
prior to publication in such form and format as may be mutually agreed to by the
Parties. Both Parties shall use their best efforts to ensure the accurate
listing of such information.

           15.1.4  Ameritech or its Publisher must receive all Primary Listings
of Focal Directory Customers prior to the service order close date for the 
directory in which those listings are to appear. Ameritech or its Publisher will
provide Focal with appropriate service order close dates within thirty (30) days
of this information becoming available.

           15.1.5  Publisher may, at no charge, include Primary Listings of
Focal Directory Customers that Focal provides to Ameritech in other directories
published by Publisher or its Affiliate.

                                      61
<PAGE>
 
           15.1.6   Nothing in this Agreement shall restrict Ameritech's
Publisher's authority as publisher of the directories from altering the
geographic scope, directory life, headings, content or format of the
directories. Publisher will provide information on such alterations at the same
time such information is provided to Ameritech.

           15.1.7   Publisher shall include, in the customer information section
of each White Pages and Yellow Pages Directory, information about Focal
services, including addresses and telephone numbers for Focal Customer service.
The form and content of such customer information shall be provided by Focal to
Ameritech or its Publisher. The charge, if any, for the listing, of such
information will be calculated on the same basis as the charges, if any, paid by
Ameritech for similar listings.

     15.2  LISTING AND LISTING UPDATES. Focal will provide Focal Directory
Customer Listings and Listing Updates to Ameritech or its Publisher on a
nonexclusive basis as follows:

           15.2.1   Focal shall provide its Focal Directory Customer Listings to
Ameritech or its Publisher in a mutually agreeable form and format. Focal
acknowledges that Ameritech or its Publisher may impose a charge for changes to
Focal Directory Customer Listings previously provided by Focal to Ameritech or 
its Publisher.

           15.2.2   Within one (1) Business Day of installation, disconnection
or other change in service (including change of nonlisted or nonpublished
status) affecting the directory assistance database or the directory listing of
an Focal Directory Customer, Focal shall provide Listing Updates to Ameritech or
its Publisher in a form and format acceptable to Publisher Listing Updates on
Focal Directory Customers are to be provided to Ameritech and Listing Updates
for facilities-based Customers of Focal shall be provided to Publisher.

           15.2.3   Focal will cooperate with Publisher to develop a cost-
effective, mutually satisfactory, mechanized or electronic process for the
provision of Focal's Listing Updates to Publisher, which process shall be
available for joint testing within six (6) months of the Effective Date.

           15.2.4   Publisher or Ameritech may sell or license the use of 
Customer Listings, or Listing Updates to third persons without the prior written
consent of Focal; provided, however, that Publisher or Ameritech will not:
                  --------  -------
 
           (a)      disclose nonlisted name and address information to any third
                    person, except as may be necessary to undertake delivery of
                    directories, or to perform other services contemplated 
                    under this Agreement;

           (b)      disclose to any third person the identity of a Customer's or
                    resale Customer's LEC;

           (c)      sell or license such Customer listing information sorted 
                    by carrier, or

                                      62
<PAGE>
 
           (d)      disclose listing information for individual cases where
                    Focal has notified Ameritech to not include listing for
                    third party publication.

           15.2.5   Publisher shall provide initial and secondary delivery of
appropriate White Page Directories for resale Customers of Focal on the same
basis as Publisher delivers White Pages Directories to Ameritech's retail
Customers. Publisher and Focal may enter into a separate directory services
agreement which, among the services provided, would include the delivery of
White Page Directories to facilities-based Customers of Focal.

                                  ARTICLE XVI
                     ACCESS TO POLES, DUCTS, CONDUITS AND
            RIGHTS-OF-WAY -- SECTIONS 251(b)(4) AND 224 OF THE ACT
            AND SECTION 361 OF THE MICHIGAN TELECOMMUNICATIONS ACT
                             (M.C.L. (S)484.2361)
                                        
     16.1  STRUCTURE AVAILABILITY.

           16.1.1   Ameritech shall make available, to the extent it may 
lawfully do so, access to poles, ducts, conduits and Rights-of-way (individually
and collectively, "STRUCTURE") owned or controlled by Ameritech for the
placement of Focal's telecommunications equipment and related facilities
("ATTACHMENTS"). "POLES, DUCTS AND CONDUITS" include entrance facilities and
conduit and riser space; controlled environmental vaults, manholes, telephone
equipment closets, remote terminals, cross-connect cabinets, panels or boxes,
equipment cabinets, pedestals, or terminals, and any other infrastructure used
by Ameritech to place telecommunications distribution facilities. "RIGHTS-OF-
WAY" are easements, licenses or any other right, whether based upon grant,
reservation, contract, law or otherwise, to use property if the property is 
used for distribution facilities. The availability of Ameritech Structure for 
Focal's Attachments is subject to and dependent upon all rights, privileges, 
franchises or authorities granted by governmental entities with jurisdiction, 
existing and future agreements with other persons not inconsistent with SECTION
                                                                        -------
16.19, all interests in property granted by persons or entities public or 
-----
private, and Applicable Law, and all terms, conditions and limitations of any 
or all of the foregoing, by which Ameritech owns and controls Structure or 
interests therein.

           16.1.2   Ameritech will not make Structure available (1) where, after
taking all reasonable steps to accommodate such request, there is Insufficient
Capacity to accommodate the requested Attachment, and (2) an Attachment cannot
be accommodated based upon nondiscriminatorily applied considerations of safety,
reliability or engineering principles. For purposes of this ARTICLE XVI,
                                                            -----------
"INSUFFICIENT CAPACITY" means the lack of existing available space on or in
Structure and the inability to create the necessary space by taking all
reasonable steps to do so. Before denying a request for access based upon 
Insufficient Capacity, Ameritech will, in good faith, explore potential 
accommodations with Focal. If Ameritech denies a request by Focal for access to
its Structure for Insufficient Capacity, safety, reliability or engineering

                                      63
<PAGE>
 
reasons, Ameritech will provide Focal a detailed, written reason for such denial
as soon as practicable but, in any event, within forty-five (45) days of the
date of such request.

     16.2 FRANCHISES, PERMITS AND CONSENTS. Focal shall be solely
responsible to secure any necessary franchises, permits or consents from
federal, state, county or municipal authorities and from the owners of private
property, to construct and operate its Attachments at the location of the
Ameritech Structure it uses. Focal shall indemnify Ameritech against loss
directly resulting from any actual lack of Focal's lawful authority to occupy
such Rights-of-way and construct its Attachments therein.

     16.3 ACCESS AND MODIFICATIONS. Where necessary to accommodate a request for
access of Focal, and provided Ameritech has not denied access as described in
SECTION 16.1.2, or because Ameritech may not lawfully make the Structure
--------------
available, Ameritech will, as set forth below, modify its Structure in order to
accommodate the Attachments of Focal. Ameritech may permit Focal to conduct
Field Survey Work and Make Ready Work itself or through its own contractors in
circumstances where Ameritech is unable to complete such work in a reasonable
time frame.

          16.3.1  Before commencing the work necessary to provide such
additional capacity, Ameritech will notify all other parties having Attachments
on or in the Structure of the proposed modification to the Structure. The
modification to accommodate Focal, may at Ameritech's option, include
modifications required to accommodate other attaching parties, including
Ameritech, that desire to modify their Attachments.

          16.3.2  If Focal requests access to an Ameritech Right-of-way
where Ameritech has no existing Structure, Ameritech shall not be required to
construct new poles, conduits or ducts, or to bury cable for Focal but will be
required to make the Right-of-way available to Focal to construct its own poles,
conduits or ducts or to bury its own cable; provided, however, if Ameritech
                                            --------  -------
desires to extend its own Attachments, Ameritech will construct Structure to
accommodate Focal's Attachments.

          16.3.3  The costs of modifying a Structure to accommodate Focal's
request, the requests of another attaching party or the needs of Ameritech shall
be borne by Focal, the other requesting party or Ameritech, respectively, except
that if other parties obtain access to the Structure as a result of the
modification, such parties shall share in the cost of modification
proportionately with the party initiating the modification. An attaching party,
including Ameritech, with a pre-existing Attachment to the Structure to be
modified to accommodate Focal shall be deemed to directly benefit from the
modification if, after receiving notification of the modification, it adds to or
modifies its Attachment. If a party, including Ameritech, uses the modification
to bring its Structure or Attachments into compliance with applicable safety or
other requirements, it shall be considered as sharing in the modification and
shall share the costs of the modification attributable to its upgrade.
Notwithstanding the foregoing, an attaching party or Ameritech with a pre-
existing Attachment to the Structure shall not be required to bear any of the
costs of rearranging or replacing its Attachment if such rearrangement or
replacement is

                                      64 
<PAGE>
 
necessitated solely as a result of an additional Attachment or the modification
of an existing Attachment sought by another attaching party. If an attaching
party, including Ameritech, makes an Attachment to the facility after the
completion of the modification, such party shall share proportionately in the
cost of the modification if such modification rendered the added attachment
possible.

          16.3.4  All modifications to Ameritech's Structure will be owned by
Ameritech. Focal and other parties, including Ameritech, who contributed to the
cost of a modification, may recover their proportionate share of the depreciated
value of such modifications from parties subsequently seeking Attachment to the
modified structure. Any necessary procedures with respect to a Party's recovery
of its proportionate share of the value of any modifications shall be as
prescribed by the Implementation Team.

     16.4 INSTALLATION AND MAINTENANCE RESPONSIBILITY. Focal shall, at its own
expense, install and maintain its Attachments in a safe condition and in
thorough repair so as not to conflict with the use of the Structure by Ameritech
or by other attaching parties. Work performed by Focal on, in or about
Ameritech's Structures shall be performed by properly trained, competent workmen
skilled in the trade. Ameritech will specify the location on the Structure where
Focal's Attachment shall be placed, which location shall be designated in a
nondiscriminatory manner. Focal shall construct each Attachment in conformance
with the permit issued by Ameritech for such Attachment. Other than routine
maintenance and service wire Attachments, Focal shall not modify, supplement or
rearrange any Attachment without first obtaining a permit therefore. Focal shall
provide Ameritech with notice before entering any Structure for construction or
maintenance purposes.

     16.5 INSTALLATION AND MAINTENANCE STANDARDS. Focal's Attachments shall be
installed and maintained in accordance with the rules, requirements and
specifications of the National Electrical Code. National Electrical Safety Code,
Bellcore Construction Practices, the Commission, the Occupational Safety &
Health Act and the valid and lawful rules, requirements and specifications of
any other governing authority having jurisdiction over the subject matter.

     16.6 IMPLEMENTATION TEAM. The Implementation Team to be formed pursuant to
ARTICLE XVIII shall develop cooperative procedures for implementing the terms of
-------------                                                                   
this ARTICLE XVI and to set out such procedures in the Implementation Plan. The
     -----------
Parties, through the Implementation Team, shall develop mutually agreeable
intervals for completion of process steps in providing Focal access to
Ameritech's Structure and appropriate penalties for failure to timely complete
process steps for which fixed intervals or negotiated intervals have been
assigned. Ameritech will provide Focal with access to information regarding the
provision of access to Ameritech's Structure which will be sufficient for Focal
to verify that Ameritech is providing Focal with access to its Structure that is
comparable to that provided by Ameritech to itself, its subsidiaries, Affiliates
and other persons requesting access to Ameritech's Structure.

     16.7 ACCESS REQUESTS. Any request by Focal for access to Ameritech's 
Structure shall be in writing and submitted to Ameritech's Structure Leasing 
Coordinator. Ameritech may

                                      65
<PAGE>
 
prescribe a reasonable process for orderly administration of such requests.
Focal's Attachment to Ameritech's Structure shall be pursuant to a permit issued
by Ameritech for each request for access.

     16.8  UNUSED SPACE. Excepting maintenance ducts as provided in SECTION 16.9
                                                                    ------------
and ducts required to be reserved for use by municipalities, all useable but
unused space on Structure owned or controlled by Ameritech shall be available
for the Attachments of Focal, Ameritech or other providers of Telecommunications
Services or cable television systems. Focal may not reserve space on Ameritech
Structure for its future needs. Ameritech shall not reserve space on Ameritech
Structure for the future need of Ameritech nor permit any other person to
reserve such space. Notwithstanding the foregoing, Focal may provide Ameritech
with a two (2)-year rolling forecast of its growth requirements for Structure
that will be reviewed jointly on an annual basis.

     16.9  MAINTENANCE DUCTS. One duct and one inner-duct in each conduit
section shall be kept vacant as maintenance ducts. Maintenance ducts shall be
made available to Focal for maintenance purposes if it has a corresponding
Attachment.

     16.10 APPLICABILITY. The provisions of this Agreement shall apply to
all Ameritech Structure now occupied by Focal except for structures covered in
the provisions of Focal Ameritech Easement or Condominium Agreements listed in
SCHEDULE 16.10.
--------------

     16.11 OTHER ARRANGEMENTS. Focal's use of Ameritech Structure is subject to
any valid, lawful and nondiscriminatory arrangements Ameritech may now or
hereafter have with others pertaining to the Structure.

     16.12 COST OF CERTAIN MODIFICATIONS. If Ameritech is required by a
governmental entity, court or Commission to move, replace or change the
location, alignment or grade of its conduits or poles, each Party shall bear its
own expenses of relocating its own equipment and facilities. However, if such
alteration is required solely due to Ameritech's negligence in originally
installing the structure, Ameritech shall be responsible for Focal's expenses.

     16.13  MAPS AND RECORDS. Ameritech will provide Focal, at Focal's request
and expense, with access to and copies of maps, records and additional
information relating to its Structure; provided that Ameritech may redact any
                                       --------                              
proprietary information (of Ameritech or third parties) contained or reflected
in any such maps, records or additional information before providing such
information to Focal. Upon request, Ameritech will meet with Focal to clarify
matters relating to maps, records or additional information. Ameritech does not
warrant the accuracy or completeness of information on any maps or records.

     16.14  FOCAL ACCESS. Focal shall provide Ameritech with notice before
entering any Ameritech Structure.

     16.15  OCCUPANCY PERMIT. Focal occupancy of Structure shall be pursuant to
a permit issued by Ameritech for each requested Attachment. Any such permit
shall terminate (a) if 
                                 
                                      66 
<PAGE>
 
Focal's franchise, consent or other authorization from federal, state, county or
municipal entities or private property owners is terminated, (b) if Focal has
not placed and put into service its Attachments within one hundred eighty (180)
days from the date Ameritech has notified Focal that such Structure is available
for Focal's Attachments, (c) if Focal ceases to use such Attachment for any
period of one hundred eighty (180) consecutive days, (d) if Focal fails to
comply with a material term or condition of this ARTICLE XVI and does not
                                                 -----------             
correct such noncompliance within sixty (60) days after receipt of notice
thereof from Ameritech or (e) if Ameritech ceases to have the right or authority
to maintain its Structure, or any part thereof, to which Focal has Attachments.
If Ameritech ceases to have the right or authority to maintain its Structure, or
any part thereof, to which Focal has Attachments, Ameritech shall (i) provide
Focal notice within ten (10) Business Days after Ameritech has knowledge of such
fact and (ii) not require Focal to remove its Attachments from such Structure
prior to Ameritech's removal of its own attachments. Ameritech will provide
Focal with at least sixty (60) days' written notice prior to (x) terminating a
permit or service to an Focal Attachment or removal thereof for a breach of the
provisions of this ARTICLE XVI, (y) any increase in the rates for Attachments to
                   -----------                                                  
Ameritech's Structure permitted by the terms of this Agreement, or (z) any
modification to Ameritech's Structure to which Focal has an Attachment, other
than a modification associated with routine maintenance or as a result of an
emergency. If Focal surrenders its permit for any reason (including forfeiture
under the terms of this Agreement), but fails to remove its Attachments from the
Structure within one hundred eighty (180) days after the event requiring Focal
to so surrender such permit, Ameritech shall remove Focal's Attachments at
Focal's expense.

     16.16  INSPECTIONS. Ameritech may make periodic inspections of any part of
the Attachments of Focal located on Ameritech Structures. Where reasonably
practicable to do so, Ameritech shall provide prior written notice to Focal of
such inspections.

     16.17  DAMAGE TO ATTACHMENTS. Both Focal and Ameritech will exercise
precautions to avoid damaging the Attachments of the other or to any Ameritech
Structure to which Focal obtains access hereunder Subject to the limitations in
ARTICLE XXVI, the Party damaging the Attachments of the other shall be 
------------                                                          
responsible to the other therefor.

     16.18  CHARGES. Ameritech's charges for Structure provided hereunder shall
be determined in compliance with the regulations to be established by the FCC
pursuant to Section 224 of the Act and in compliance with Section 361 of the
Michigan Telecommunications Act (M.C.L. (S)484 2361) and applicable Commission
rules, regulations and orders thereunder. Prior to the establishment of such
rates, Ameritech's charges for Structure will be those of the lowest existing
contract available to an attaching party in the State of Michigan, including any
Affiliate of Ameritech. A deposit shall be required for map preparation, make-
ready surveys and Make-Ready Work.

     16.19  NONDISCRIMINATION. Except as otherwise permitted by Applicable Law,
access to Ameritech-owned or -controlled Structure shall be provided to Focal on
a basis that is nondiscriminatory to that which Ameritech provides to itself,
its Affiliates, Customers, or any other person.

                                      67
<PAGE>
 
     16.20 INTERCONNECTION.

           16.20.1  Upon request by Focal, Ameritech will permit the
interconnection of ducts or conduits owned by Focal in Ameritech manholes.

           16.20.2  Except where required herein, requests by Focal for
interconnection of Focal's Attachments in or on Ameritech Structure with the
Attachments of other attaching parties in or on Ameritech Structure will be
considered on a case-by-case basis and permitted or denied based on the
applicable standards set forth in this ARTICLE XVI for and reasons of
                                       -----------                   
insufficient Capacity, safety, reliability and engineering. Ameritech will
provide a written response to Focal's request within forty-five (45) days of
Ameritech's receipt of such request.

           16.20.3  Focal shall be responsible for the costs of any Make-Ready
Work required to accommodate any interconnection pursuant to SECTION 16.20.
                                                             -------------

     16.21 COST IMPUTATION. Ameritech will impute costs consistent with the
rules under Section 224(g) of the Act.

     16.22 STRUCTURE LEASING COORDINATOR. Requests for access to Ameritech
Structure shall be made through Ameritech's Structure Leasing Coordinator, who
shall be Focal's single point of contact for all matters relating to Focal's
access to Ameritech's Structure. The Structure Leasing Coordinator shall be
responsible for processing requests for access to Ameritech's Structure,
administration of the process of delivery of access to Ameritech's Structure and
for all other matters relating to access to Ameritech's Structure.

     16.23 STATE REGULATION. The terms and conditions in this ARTICLE XVI shall
                                                              -----------
be modified through negotiation between the Parties to comply with the
regulations of the state in which Ameritech owns or controls Structure to which
Focal seeks access if such state meets the requirements of Section 224(c) of the
Act for regulating rates, terms and conditions for pole attachments and so
certifies to the FCC under Section 224(c) of the Act and the applicable FCC
rules pertaining hereto. The terms and conditions of this ARTICLE XVI shall also
                                                          -----------           
be modified by negotiation between the Parties to comply with any applicable
requirements regarding the application of state law set forth in applicable
Commission rules, regulations and orders and the Michigan Telecommunications 
Act. Until the terms and conditions of this ARTICLE XVI are renegotiated, the
                                            -----------
rules, regulations and orders of such state so certifying shall supersede any
provision herein inconsistent therewith.

     16.24 ABANDONMENTS, SALES OR DISPOSITIONS. Ameritech shall notify Focal of
the proposed abandonment, sale, or other intended disposition of any Structure.
In the event of a sale or other disposition of the conduit system or pole,
Ameritech shall condition the sale or other disposition subject to the rights
granted to Focal.

                                    68    
<PAGE>
 
     16.25 STANDARDS OF PERFORMANCE. Ameritech shall provide Structure to Focal
in accordance with the service levels, procedures and intervals, if any, agreed
upon by the Implementation Team as provided in SECTION 18.6.
                                               ------------

                                 ARTICLE XVII
                             REFERRAL ANNOUNCEMENT

     When a Customer changes its service provider from Ameritech to Focal, or
from Focal to Ameritech, and does not retain its original telephone number, the
Party formerly providing service to such Customer shall provide a referral
announcement ("REFERRAL ANNOUNCEMENT") on the abandoned telephone number which
provides details on the Customer's new number. Referral Announcements shall be
provided reciprocally, free of charge to both the other Party and the Customer,
for the period specified in Michigan Administrative Rule 484,134. However, if
either Party provides Referral Announcements for a period longer than the above
period when its Customers change their telephone numbers, such Party shall
provide the same level of service to Customers of the other Party.


                                 ARTICLE XVIII
                  IMPLEMENTATION TEAM AND IMPLEMENTATION PLAN

     18.1  IMPLEMENTATION TEAM. The Parties understand that the arrangements and
provision of services described in this Agreement shall require technical and
operational coordination between the Parties. The Parties further agree that it
is not feasible for this Agreement to set forth each of the applicable and
necessary procedures, guidelines, specifications and standards that will promote
the Parties' provision of Telecommunications Services to their respective
Customers. Accordingly, the Parties agree to form a team (the "IMPLEMENTATION
TEAM") which shall develop and identify those processes, guidelines,
specifications, standards and additional terms and conditions necessary for the
provision of the services and the specific implementation of each Party's
obligations hereunder. Within five (5) days after the Effective Date,/11/ each
Party shall designate, in writing, not more than four (4) persons to be
permanent members of the Implementation Team; provided that either Party may
                                              --------
include in meetings or activities such technical specialists or other
individuals as may be reasonably required to address a specific task, matter or
subject. Each Party may replace its representatives on the Implementation Team
by delivering written notice thereof to the other Party. The processes described
in this ARTICLE XVIII and agreement reached by the Parties in the Implementation
        -------------                                                           
Plan shall not (i) relieve either Party of its obligations to perform any duties
under this Agreement, the Act or any obligation which must be performed by
January 1, 1997 as

______________________

/11/ Since the terms of this Agreement are the result of Focal's adoption under
     Section 252(i) of the Act of the Teligent Agreement, the Parties agree that
     the term "Effective Date", for purposes of this SECTION 18.1 shall mean
                                                     ------------ 
     February 10, 1999.
     
                                      69
<PAGE>
 
imposed by the FCC or (ii) constitute a waiver of a right of either Party to
claim that the parity requirements of this Agreement and of the Act have or have
not been met.

     18.2  IMPLEMENTATION PLAN. Within ninety (90) days after the Effective 
Date,/12/ the Implementation Team shall reach agreements on items to be
      --
included in an operations manual (the "IMPLEMENTATION PLAN"), which shall
include (i) processes, procedures, and milestone agreements reached by the
Implementation Team, (ii) documentation of the various items described in this
Agreement which are to be included in the Implementation Plan, including the
following matters, and (iii) any other matters agreed upon by the Implementation
Team:

     (1)   A Plan as provided in SECTION 8.1;
                                 ----------- 

     (2)   Access to all necessary OSS functions, including interfaces and
           gateways;

     (3)   Procedures that specify the requisite time period(s) in which
           Ameritech shall give Focal notice and the applicable information and
           ---------
           specifications regarding any changes to interfaces of the OSS
           functions;

     (4)   Escalation procedures for provisioning and maintenance;

     (5)   Single points of contact for provisioning and maintenance;

     (6)   Service ordering and provisioning procedures, including provision of
           the trunks and facilities;

     (7)   Provisioning and maintenance support;

     (8)   Conditioning of Collocation spaces and maintenance of Virtually
           Collocated equipment;

     (9)   Procedures and processes for Directories and Directory Listings;

     (10)  Service referral procedures, including procedures for handling
           misdirected inquiries and calls and procedures for handling out-of-
           service or irate Customers;

     (11)  Training;

     (12)  Billing, including measurements, rating and validation process;

_________________________

/12/ Since the terms of this Agreement are the result of Focal's adoption under
 --
     Section 252(i) of the Act of the Teligent Agreement, the Parties agree that
     the term "Effective Date", for purposes of this SECTION 18.2, shall mean
                                                     ------------
     February 10, 1999.

                                      70
<PAGE>
 
     (13)  Network planning components, including system architecture, planning
           SONET equipment configuration, fiber hand-off, test and acceptance of
           SONET ring, trunking, signaling, and augment process;

     (14)  Joint systems readiness and operational readiness plans; and

     (15)  Guidelines for administering access to Rights-of-way, poles and
           conduits of Ameritech.

     Subject to the terms and conditions of this Agreement (including SECTION
                                                                      ------- 
19.5), the Implementation Plan will ensure that no later than the end of
----                                                                   
Contract Month 6 /13/, the operational interfaces will be capable of supporting
all classes and complexities of orders for Network Elements and Resale Services
and all Network Elements and Resale Services are available to order, at all
required volume levels.

     18.3  ACTION OF IMPLEMENTATION TEAM. The Implementation Plan may be amended
from time to time by the Implementation Team as the team deems appropriate.
Unanimous written consent of the permanent members of the Implementation Team
shall be required for any action of the Implementation Team. If the
Implementation Team is unable to act, the existing provisions of the
Implementation Plan shall remain in full force and effect.

     18.4  FURTHER COORDINATION AND PERFORMANCE. Except as otherwise agreed upon
by the Parties, on a mutually agreed-upon day and time once a month during the
Term, the Implementation Team shall discuss the performance of the Parties under
this Agreement. At each such monthly meeting the Parties will discuss: (i) the
administration and maintenance of the Interconnections and trunk groups
provisioned under this Agreement; (ii) the Parties' provisioning of the services
provided under this Agreement; (iii) the Parties' compliance with the
Performance Benchmarks set forth in this Agreement and any areas in which such
performance may be improved; (iv) any problems that were encountered during the
preceding month or anticipated in the upcoming month; (v) the reason underlying
any such problem and the effect, if any, that such problem had, has or may have
on the performance of the Parties; and (vi) the specific steps taken or proposed
to be taken to remedy such problem. In addition to the foregoing, the Parties
through their representatives on the Implementation Team or such other
appropriate representatives will meet to discuss any matters that relate to the
performance of this Agreement, as may be requested from time to time by either
of the Parties.

________________________

/13/ Since the terms of this Agreement are the result of Focal's adoption under
     Section 252(i) of the Act of the Teligent Agreement, the Parties agree that
     the term "Contract Month 6", for purposes of this SECTION 18.2, shall
                                                       ------------
     expire on July 31, 1999.

                                      71
<PAGE>
 
     18.5  OPERATIONAL REVIEW. Representatives of Focal and Ameritech will meet
on a quarterly basis, beginning with the end of the first quarter of 1997, /14/
                                                                            --
to determine that the service cycle of pre-ordering, ordering, provisioning,
maintenance and billing categories are addressed, including the following:

           (a) Interfaces and processes are operational and the agreed-upon
               numbers of Focal Customers for residential and business Resale
               Services are successfully completed per day;

           (b) Interfaces and processes are operational and the agreed-upon
               numbers of orders for Combinations are successfully completed per
               day;

           (c) When applicable, Interfaces and processes are operational and the
               agreed-upon numbers of orders for unbundled Loops are
               successfully completed per day;

           (d) Review of all agreed-upon performance standards; and

           (e) The accuracy rate for bills for wholesale bill validation
               process.

     18.6  ADDITIONAL DUTIES OF IMPLEMENTATION TEAM. In addition to its
responsibilities under SECTION 18.2, the Implementation Team shall meet in the
                       ------------                                           
fourth Contract Month /15/ after Ameritech first:
                       --

           (1) Provides Focal unbundled Network Elements (or any Combination
               thereof) hereunder, to determine if any additional Network
               Element Performance Activities are required to assess Ameritech's
               performance under SECTION 9.10;
                                 ------------

           (2) Delivers Collocated Space to Focal hereunder, to determine if any
               service levels, procedures or intervals are required to assess
               Ameritech's provision of Collocation under SECTIONS 12.4 and
                                                          ------------- 
               12.12 and the applicable remedies, if any, for Ameritech's
               -----
               failure to perform with any of the foregoing service levels,
               procedures and intervals; and

________________________

/14/ Since the terms of this Agreement are the result of Focal's adoption under
     Section 252 (i) of the Act of the Teligent Agreement, the Parties agree
     that the phrase "second quarter of 1999" shall be substituted in lieu of
     the phrase "first quarter of 1997."

/15/ Since the terms of this Agreement are the result of Focal's adoption under
     Section 252(i) of the Act of the Focal Agreement, the Parties agree that
     the term "Fourth Contract Month", for purposes of this SECTION 18.6, shall
                                                            ------------   
     expire on May 30, 1999.

                                      72
<PAGE>
 
           (3) Provides Focal access to Ameritech Structure hereunder, to
               determine if any service levels, procedures or intervals are
               required to assess Ameritech's provision of Structure under
               SECTIONS 16.6 and 16.19 and the applicable remedies, if any, for
               -------------     -----                   
               Ameritech's failure to perform with any of the foregoing service
               levels, procedures and intervals.

If the Implementation Team is unable to agree upon any of the foregoing service
levels, procedures or intervals or applicable remedies (or whether any such
service levels, procedures, intervals or remedies are necessary), such failure
to agree shall be resolved in accordance with the procedures established in
SECTION 28.3.
------------

                                  ARTICLE XIX
                    GENERAL RESPONSIBILITIES OF THE PARTIES

     19.1  COMPLIANCE WITH IMPLEMENTATION SCHEDULE. Each of Ameritech and Focal
shall use its best efforts to comply with the Implementation Schedule.

     19.2  COMPLIANCE WITH APPLICABLE LAW. Each Party shall comply at its own
expense with all applicable federal, state, and local statutes, laws, rules,
regulations, codes, final and nonappealable orders, decisions, injunctions,
judgments, awards and decrees (collectively, "APPLICABLE LAW") that relate to
its obligations under this Agreement.

     19.3  NECESSARY APPROVALS. Each Party shall be responsible for obtaining
and keeping in effect all approvals from, and rights granted by, governmental
authorities, building and property owners, other carriers, and any other persons
that may be required in connection with the performance of its obligations under
this Agreement. Each Party shall reasonably cooperate with the other Party in
obtaining and maintaining any required approvals and rights for which such Party
is responsible.

     19.4  ENVIRONMENTAL HAZARDS. Each Party will be solely responsible at it
own expense for the proper handling, storage, transport, treatment, disposal and
use of all Hazardous Substances by such Party and its contractors and agents.
"HAZARDOUS SUBSTANCES" includes those substances (i) included within the
definition of hazardous substance, hazardous waste, hazardous material, toxic
substance, solid waste or pollutant or contaminant under any Applicable Law and
(ii) listed by any governmental agency as a hazardous substance.

     19.5  FORECASTING REQUIREMENTS.

           19.5 1   The Parties shall exchange technical descriptions and
forecasts of their Interconnection and traffic requirements in sufficient detail
necessary to establish the Interconnections required to assure traffic
completion to and from all Customers in their respective designated service
areas.

                                      73
<PAGE>
 
          19.5.2    Thirty (30) days after the Effective Date/16/ and each month
                                                              --
during the term of this Agreement, each Party shall provide the other Party with
a rolling, six (6) calendar-month, nonbinding forecast of its traffic and volume
requirements for the Interconnection, and Network Elements provided under this
Agreement, in the form and in such detail as agreed by the Parties.
Notwithstanding SECTION 20.1.1, the Parties agree that each forecast provided
                --------------                                               
under this SECTION 19.5.2 shall be deemed "PROPRIETARY INFORMATION" under 
           --------------                                                
ARTICLE XX.
----------           

          19.5.3 In addition to, and not in lieu of, the nonbinding forecasts
required by SECTION 19.5.2, a Party that is required pursuant to this 
Agreement--------------to provide a forecast (the "FORECAST PROVIDER") or a
Party that is entitled pursuant to this Agreement to receive a forecast (the
"FORECAST RECIPIENT") with respect to traffic and volume requirements for the
services and Network Elements provided under this Agreement may request that the
other Party enter into to negotiations to establish a forecast (a "BINDING
FORECAST") that commits such Forecast Provider to purchase, and such Forecast
Recipient to provide, a specified volume to be utilized as set forth in such
Binding Forecast. The Forecast Provider and Forecast Recipient shall negotiate
the terms of such Binding Forecast in good faith and shall include in such
Binding Forecast provisions regarding price, quantity, liability for failure to
perform under a Binding Forecast and any other terms desired by such Forecast
Provider and Forecast Recipient. Notwithstanding SECTION 20.1.1, the Parties
agree that each--------------forecast provided under this SECTION 19.5.3 shall
be deemed "PROPRIETARY--------------INFORMATION" under ARTICLE XX.----------

     19.6  CERTAIN NETWORK FACILITIES. Each Party is individually responsible to
provide facilities within its network which are necessary for routing,
transporting, measuring, and billing traffic from the other Party's network and
for delivering such traffic to the other Party's network using industry standard
format and to terminate the traffic it receives in that standard format to the
proper address on its network. Such facility shall be designed based upon the
description and forecasts provided under SECTIONS 19.5.1, 19.5.2 and, if 
                                         ---------------  ------
applicable, 19.5.3. The Parties are each solely responsible for participation in
            ------
and compliance with national network plans, including The National Network
Security Plan and The Emergency Preparedness Plan.

     19.7  TRAFFIC MANAGEMENT AND NETWORK HARM.

           19 7.1   Each Party may use protective network traffic management
controls, such as 7-digit and 10-digit code gaps on traffic toward the other
Party's network, when required to protect the public-switched network from
congestion due to facility failures, switch congestion or failure or focused
overload. Each Party shall immediately notify the other Party of any protective
control action planned or executed.


------------------------

/16/ Since the terms of this Agreement are the result of Focal's adoption under
 --
     Section 252(i) of the Act of the Teligent Agreement, the Parties agree that
     the term "Effective Date", for purposes of this SECTION 19.5.2, shall mean
                                                     --------------
     February 10, 1999.

                                      74
<PAGE>
 
          19.7.2    Where the capability exists, originating or terminating
traffic reroutes may be implemented by either Party to temporarily relieve
network congestion due to facility failures or abnormal calling patterns.
Reroutes shall not be used to circumvent normal trunk servicing. Expansive
controls shall be used only when mutually agreed to by the Parties.

          19.7.3    The Parties shall cooperate and share pre-planning
information regarding cross-network call-ins expected to generate large or
focused temporary increases in call volumes, to prevent or mitigate the impact
of these events on the public-switched network.

          19.7.4    Neither Party shall use any product or service provided
under this Agreement or any other service related thereto or used in combination
therewith in any manner that interferes with any person in the use of such
person's Telecommunications Service, prevents any person from using its
Telecommunications Service, impairs the quality of Telecommunications Service to
other carriers or to either Party's Customers, causes electrical hazards to
either Party's personnel, damage to either Party's equipment or malfunction of
either Party's billing equipment.

     19.8   INSURANCE. At all times during the term of this Agreement, each
Party shall keep and maintain in force at such Party's expense all insurance
required by Applicable Law, general liability insurance in the amount of at
least $10,000,000 and worker's compensation insurance. Upon request from the
other Party, each Party shall provide to the other Party evidence of such
insurance (which may be provided through a program of self-insurance).

     19.9   LABOR RELATIONS. Each Party shall be responsible for labor relations
with its own employees. Each Party agrees to notify the other Party as soon as
practicable whenever such Party has knowledge that a labor dispute concerning
its employees is delaying or threatens to delay such Party's timely performance
of its obligations under this Agreement and shall endeavor to minimize
impairment of service to the other Party (by using its management personnel to
perform work or by other means) in the event of a labor dispute to the extent
permitted by Applicable Law.

     19.10  GOOD FAITH PERFORMANCE. Each Party shall act in good faith in its
performance under this Agreement and, in each case in which a Party's consent or
agreement is required or requested hereunder, such Party shall not unreasonably
withhold or delay such consent or agreement, as the case may be.

     19.11  RESPONSIBILITY TO CUSTOMERS. Each Party is solely responsible to its
Customers for the services it provides to such Customers.

     19.12  UNNECESSARY FACILITIES. No Party shall construct facilities which
require another Party to build unnecessary facilities.

                                      75
<PAGE>
 
     19.13   COOPERATION. The Parties shall work cooperatively to minimize fraud
associated with third-number billed calls, calling card calls, and any other
services related to this Agreement.

     19.14   NXX CODE ADMINISTRATION. Each Party is responsible for
administering NXX codes assigned to it.

     19.15   LERG LISTINGS. Each Party is responsible for obtaining Local
Exchange Routing Guide ("LERG") listings of CLLI codes assigned to its switches.

     19.16   LERG USE. Each Party shall use the LERG published by Bellcore or
its successor for obtaining routing information and shall provide all required
information to Bellcore for maintaining the LERG in a timely manner.

     19.17   SWITCH PROGRAMMING. Each Party shall program and update its own
Central Office Switches and End Office Switches and network systems to recognize
and route traffic to and from the other Party's assigned NXX codes. Except as
mutually agreed or as otherwise expressly defined in this Agreement, neither
Party shall impose any fees or charges on the other Party for such activities.

     19.18   TRANSPORT FACILITIES. Each Party is responsible for obtaining
transport facilities sufficient to handle traffic between its network and the
other Party's network. Each Party may provide the facilities itself, order them
through a third party, or order them from the other Party.

                                  ARTICLE XX
                            PROPRIETARY INFORMATION

     20.1    DEFINITION OF PROPRIETARY INFORMATION.

             20.1.1  "PROPRIETARY INFORMATION" means:

             (a)    all proprietary or confidential information of a Party (a
                    "DISCLOSING PARTY") including specifications, drawings,
                    sketches, business information, forecasts, records
                    (including each Party's records regarding Performance
                    Benchmarks), Customer Proprietary Network Information,
                    Customer Usage Data, audit information, models, samples,
                    data, system interfaces, computer programs and other
                    software and documentation that is furnished or made
                    available or otherwise disclosed to the other Party or any
                    of such other Party's Affiliates (individually and
                    collectively, a "RECEIVING PARTY") pursuant to this
                    Agreement and, if written, is marked "Confidential" or
                    "Proprietary" or by other similar notice or if oral or
                    visual, is identified as "Confidential" or "Proprietary" at
                    the time of disclosure; and

                                       76
<PAGE>
 
             (b)    any portion of any notes, analyses, data, compilations,
                    studies, interpretations or other documents prepared by any
                    Receiving Party to the extent the same contain, reflect, are
                    derived from, or are based upon, any of the information
                    described in subsection (a) above, unless such information
                    contained or reflected in such notes, analyses, etc. is so
                    commingled with the Receiving Party's information that
                    disclosure could not possibly disclose the underlying
                    proprietary or confidential information (such portions of
                    such notes, analyses, etc. referred to herein as "DERIVATIVE
                    INFORMATION").

             20.1.2 The Disclosing Party will use its reasonable efforts to
follow its customary practices regarding the marking of tangible Proprietary
Information as "confidential," "proprietary," or other similar designation. The
Parties agree that the designation in writing by the Disclosing Party that
information is confidential or proprietary shall create a presumption that such
information is confidential or proprietary to the extent such designation is
reasonable.

             20.1.3 Notwithstanding the requirements of this ARTICLE XX, all
                                                             ----------
information relating to the Customers of a Party, including information that
would constitute Customer Proprietary Network Information of a Party pursuant to
the Act and FCC rules and regulations, and Customer Usage Data, whether
disclosed by one Party to the other Party or otherwise acquired by a Party in
the course of the performance of this Agreement, shall be deemed "PROPRIETARY
INFORMATION."

       20.2  DISCLOSURE AND USE.

             20.2.1 Each Receiving Party agrees that from and after the
                    Effective Date:/17/
                                    --

             (a)    all Proprietary Information communicated, whether before,
                    on or after the Effective Date, to it or any of its
                    contractors, consultants or agents ("REPRESENTATIVES") in
                    connection with this Agreement shall be held in confidence
                    to the same extent as such Receiving Party holds its own
                    confidential information; provided that such Receiving
                                              --------
                    Party or Representative shall not use less than a
                    reasonable standard of care in maintaining the
                    confidentiality of such information;

             (b)    it will not, and it will not permit any of its employees, 
                    Affiliates or Representatives to disclose such Proprietary
                    Information to any third person;

________________________________

/17/   Since the terms of this Agreement are the result of Focal's adoption
 --
       under Section 252(i) of the Act of the AT&T Agreement, the Parties agree
       that the term "Effective Date", for purposes of this SECTION 20.2.1,
                                                            --------------
       shall mean February 10, 1999.

                                      77
<PAGE>
 
             (c)     it will disclose Proprietary Information only to those of
                     its employees, Affiliates and Representatives who have a
                     need for it in connection with the use or provision of
                     services required to fulfill this Agreement; and

             (d)     it will, and will cause each of its employees, Affiliates
                     and Representatives to use such Proprietary Information
                     only to perform its obligations under this Agreement or to
                     use services provided by the Disclosing Party hereunder and
                     for no other purpose, including its own marketing purposes.

             20.2.2  A Receiving Party may disclose Proprietary Information of a
Disclosing Party to its Representatives who need to know such information to
perform their obligations under this Agreement; provided that before disclosing
                                                -------- 
any Proprietary Information to any Representative, such Party shall notify such
Representative of such person's obligation to comply with this Agreement. Any
Receiving Party so disclosing Proprietary Information shall be responsible for
any breach of this Agreement by any of its Representatives and such Receiving
Party agrees, at its sole expense, to use its reasonable efforts (including
court proceedings) to restrain its Representatives from any prohibited or
unauthorized disclosure or use of the Proprietary Information. Each Receiving
Party making such disclosure shall notify the Disclosing Party as soon as
possible if it has knowledge of a breach of this Agreement in any material
respect. A Disclosing Party shall not disclose Proprietary Information directly
to a Representative of the Receiving Party without the prior written
authorization of the Receiving Party.

             20.2.3  Proprietary Information shall not be reproduced by any
Receiving Party in any form except to the extent (i) necessary to comply with
the provisions of SECTION 20.3 and (ii) reasonably necessary to perform its
                  ------------                                             
obligations under this Agreement. All such reproductions shall bear the same
copyright and proprietary rights notices as are contained in or on the original.

             20.2.4  This SECTION 20.2 shall not apply to any Proprietary
                          ------------                                   
Information which the Receiving Party can establish to have:

             (a)     been disclosed by the Receiving Party with the Disclosing
                     Party's prior written consent;

             (b)     become generally available to the public other than as a
                     result of disclosure by a Receiving Party;

             (c)     been independently developed by a Receiving Party by an
                     individual who has not had knowledge of or direct or
                     indirect access to such Proprietary Information;

             (d)     been rightfully obtained by the Receiving Party from a
                     third person without knowledge that such third person is
                     obligated to protect its

                                      78
<PAGE>
 
                    confidentiality; provided that such Receiving Party has no
                                     --------
                    reasonable basis on which to inquire as to whether or not
                    such information was subject to a confidentiality agreement
                    at the time such information was acquired; or

             (e)     been obligated to be produced or disclosed by Applicable
                     Law; provided that such production or disclosure shall have
                          --------
                     been made in accordance with SECTION 20.3.
                                                  ------------

     20.3    GOVERNMENT DISCLOSURE.

             20.3.1 If a Receiving Party desires to disclose or provide to the
Commission, the FCC or any other governmental authority any Proprietary
Information of the Disclosing Party, such Receiving Party shall, prior to and as
a condition of such disclosure, (i) provide the Disclosing Party with written
notice and the form of such proposed disclosure as soon as possible but in any
event early enough to allow the Disclosing Party to protect its interests in the
Proprietary Information to be disclosed and (ii) attempt to obtain in accordance
with the applicable procedures of the intended recipient of such Proprietary
Information an order, appropriate protective relief or other reliable assurance
that confidential treatment shall be accorded to such Proprietary Information.

             20.3.2 If a Receiving Party is required by any governmental
authority or by Applicable Law to disclose any Proprietary Information, then
such Receiving Party shall provide the Disclosing Party with written notice of
such requirement as soon as possible and prior to such disclosure. Upon receipt
of written notice of the requirement to disclose Proprietary Information, the
Disclosing Party, at its expense, may then either seek appropriate protective
relief in advance of such requirement to prevent all or part of such disclosure
or waive the Receiving Party's compliance with this SECTION 20.3 with respect to
                                                    ------------                
all or part of such requirement.

             20.3.3 The Receiving Party shall use all commercially reasonable
efforts to cooperate with the Disclosing Party in attempting to obtain any
protective relief which such Disclosing Party chooses to seek pursuant to this
SECTION 20.3. In the absence of such relief, if the Receiving Party is legally
------------
compelled to disclose any Proprietary Information, then the Receiving Party
shall exercise all commercially reasonable efforts to preserve the
confidentiality of the Proprietary Information, including cooperating with the
Disclosing Party to obtain an appropriate order or other reliable assurance that
confidential treatment will be accorded the Proprietary Information.

     20.4    OWNERSHIP.

             20.4.1 All Proprietary Information, other than Derivative
Information, shall remain the property of the Disclosing Party, and all
documents or other tangible media delivered to the Receiving Party that embody
such Proprietary Information shall be, at the option of the

                                      79
<PAGE>
 
Disclosing Party, either promptly returned to Disclosing Party or destroyed,
except as otherwise may be required from time to time by Applicable Law (in
which case the use and disclosure of such Proprietary Information will continue
to be subject to this Agreement), upon the earlier of (i) the date on which the
Receiving Party's need for it has expired and (ii) the expiration or termination
of this Agreement (including any applicable Transition Period).

             20.4.2  At the request of the Disclosing Party, any Derivative
Information shall be, at the option of the Receiving Party, either promptly
returned to the Disclosing Party or destroyed, except as otherwise may be
required from time to time by Applicable Law (in which case the use and
disclosure of such Proprietary Information will continue to be subject to this
Agreement), upon the earlier of (i) the date on which the Receiving Party's need
for it has expired and (ii) the expiration or termination of this Agreement
(including any applicable Transition Period).

             20.4.3  The Receiving Party may at any time either return to the
Disclosing Party or destroy Proprietary Information.

             20.4.4  If destroyed, all copies shall be destroyed and upon the
written request of the Disclosing Party, the Receiving Party shall provide to
the Disclosing Party written certification of such destruction. The destruction
or return of Proprietary Information shall not relieve any Receiving Party of
its obligation to treat such Proprietary Information in the manner required by
this Agreement.

                                  ARTICLE XXI
                             TERM AND TERMINATION

     21.1    TERM. The initial term of this Agreement shall expire on January
29, 2000 (the "INITIAL TERM") which shall commence on the Effective Date. Upon
expiration of the Initial Term, this Agreement shall automatically be renewed
for additional one (1)-year periods (each, a "RENEWAL TERM") unless a Party
delivers to the other Party written notice of termination of this Agreement at
least one hundred twenty (120) days prior to the expiration of the Initial Term
or a Renewal Term.

     21.2    RENEGOTIATION OF CERTAIN TERMS. Notwithstanding the foregoing, upon
delivery of written notice at least one hundred twenty (120) days prior to the
expiration of the Initial Term or any Renewal Term, either Party may require
negotiations of the rates, prices and charges, terms, and conditions of the
services to be provided under this Agreement effective upon such expiration. If
the Parties are unable to satisfactorily negotiate such new rates, prices,
charges and terms within ninety (90) days of such written notice, either Party
may petition the Commission or take such other action as may be necessary to
establish appropriate terms. If prior to the applicable expiration date, the
Parties are unable to mutually agree on such new rates, prices, charges, terms
and conditions or the Commission does not issue its order, the

                                      80
<PAGE>
 
Parties agree that the rates, terms and conditions ultimately ordered by such
Commission or negotiated by the Parties shall be effective retroactive to such
expiration date.

     21.3    DEFAULT. When a Party believes that the other Party is in violation
of a material term or condition of this Agreement ("DEFAULTING PARTY"), it shall
provide written notice to such Defaulting Party of such violation prior to
commencing the dispute resolution procedures set forth in SECTION 28.3 and it
                                                          ------------
shall be resolved in accordance with the procedures established in SECTION 28.3.
                                                                   ------------

     21.4    TRANSITIONAL SUPPORT.

             21.4.1 In the event of the termination or expiration of this
Agreement for any reason, each Party agrees to maintain the level and quality of
services still being provided by it as of the date of termination or expiration
of this Agreement ("TRANSITION DATE"), and to cooperate reasonably in an orderly
and efficient transition to a successor provider.

             21.4.2 Each Party agrees (i) to furnish services during a period
for up to one (1) year (or such longer period as may be agreed by the Parties)
after the Transition Date ("TRANSITION PERIOD") on terms and conditions and at
charges that are the same as those in effect upon the Transition Date, and (ii)
to enter into an agreement with the other Party for a transition plan that
specifies the nature, extent, and schedule of the services to be provided during
such Transition Period. During the Transition Period, Ameritech and Focal will
cooperate in good faith to effect an orderly transition of service under this
Agreement. Ameritech and Focal agree to exercise their respective reasonable
efforts to avoid or minimize service disruptions or degradation in services
during such transition.

     21.5    PAYMENT UPON EXPIRATION OR TERMINATION. In the case of the
expiration or termination of this Agreement for any reason, each of the Parties
shall be entitled to payment for all services performed and expenses accrued or
incurred prior to such expiration or termination, provided that a Party is
                                                  --------
entitled to recover such expenses under the provisions of this Agreement.


                                 ARTICLE XXII
                 DISCLAIMER OF REPRESENTATIONS AND WARRANTIES

     EXCEPT AS EXPRESSLY PROVIDED UNDER THIS AGREEMENT, NO PARTY MAKES OR
RECEIVES ANY WARRANTY, EXPRESS, IMPLIED OR STATUTORY, WITH RESPECT TO THE
SERVICES, CONDITIONS, AND PRODUCTS IT PROVIDES OR IS CONTEMPLATED TO PROVIDE
UNDER THIS AGREEMENT AND EACH PARTY DISCLAIMS THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND/OR OF FITNESS FOR A PARTICULAR PURPOSE.

                                      81
<PAGE>
 
                                 ARTICLE XXIII
                             CANCELLATION CHARGES
                                        
     Except as provided in SECTIONS 9.1.3 and 19.5.3, pursuant to a Bona Fide
                           --------------     ------                       
Request or as otherwise provided in any applicable tariff or contract referenced
herein, cancellation charges shall not be imposed upon, or payable by, either
Party.

                                 ARTICLE XXIV
                                 SEVERABILITY

     24.1 SEVERABILITY. If any provision of this Agreement shall be held to be
illegal, invalid or unenforceable, each Party agrees that such provision shall
be enforced to the maximum extent permissible so as to effect the intent of the
Parties, and the validity, legality and enforceability of the remaining
provisions of this Agreement shall not in any way be affected or impaired
thereby. If necessary to effect the intent of the Parties, the Parties shall
negotiate in good faith to amend this Agreement to replace the unenforceable
language with enforceable language that reflects such intent as closely as
possible.

     24.2 NON-CONTRAVENTION OF LAWS. Nothing in this Agreement shall be
construed as requiring or permitting either Party to contravene any mandatory
requirement of Applicable Law.

                                  ARTICLE XXV
                                INDEMNIFICATION
                                        
     25.1 GENERAL INDEMNITY RIGHTS. Each Party (the "INDEMNIFYING PARTY") shall
defend and indemnify the other Party, its officers, directors, employees and
permitted assignees (collectively, the "INDEMNIFIED PARTY") and hold such
Indemnified Party harmless against
                           
          (a)  any Loss to a third person arising out of: the negligent acts or
               omissions, or willful misconduct ("FAULT") by such Indemnifying
               Party or the Fault of its employees, agents and subcontractors;
               provided, however, that (1) with respect to employees or agents
               of the Indemnifying Party, such Fault occurs while performing
               within the scope of their employment, (2) with respect to
               subcontractors of the Indemnifying Party, such Fault occurs in
               the course of performing duties of the subcontractor under its
               subcontract with the Indemnifying Party, and (3) with respect to
               the Fault of employees or agents of such subcontractor, such
               Fault occurs while performing within the scope of their
               employment by the subcontractor with respect to such duties of
               the subcontractor under the subcontract; 
     
                                      82
<PAGE>
 
          (b)  any Loss arising from such Indemnifying Party's use of services
               offered under this Agreement, involving pending or threatened
               claims, actions, proceedings or suits ("CLAIMS"), claims for
               libel, slander, invasion of privacy, or infringement of
               Intellectual Property rights arising from the Indemnifying
               Party's own communications or the communications of such
               Indemnifying Party's Customers;

          (c)  any Loss arising from Claims for actual or alleged infringement
               of any Intellectual Property right of a third person to the
               extent that such Loss arises from an Indemnified Party's or an
               Indemnified Party's Customer's use of a service provided under
               this Agreement; provided, however, that an Indemnifying Party's
                               --------  -------
               obligation to defend and indemnify the Indemnified Party shall
               not apply in the case of (i) (A) any use by an Indemnified Party
               of a service (or element thereof) in combination with elements,
               services or systems supplied by the Indemnified Party or persons
               other than the Indemnifying Party or (B) where an Indemnified
               Party or its Customer modifies or directs the Indemnifying Party
               to modify such service and (ii) no infringement would have
               occurred without such combined use or modification;

          (d)  any and all penalties imposed upon the Indemnifying Party's
               failure to comply with the Communications Assistance to Law
               Enforcement Act of 1994 ("CALEA") and, at the sole cost and
               expense of the Indemnifying Party, any amounts necessary to
               modify or replace any equipment, facilities or services
               provided to the Indemnified Party under this Agreement to ensure
               that such equipment, facilities and services fully comply with
               CALEA; and
               
          (e)  any Loss arising from such Indemnifying Party's failure to comply
               with Applicable Law.

     25.2 INDEMNIFICATION PROCEDURES. Whenever a Claim shall arise for
indemnification under this ARTICLE XXV, the relevant Indemnified Party, as
                           -----------                                  
appropriate, shall promptly notify, the Indemnifying Party and request the
Indemnifying Party to defend the same. Failure to so notify, the
Indemnifying Party shall not relieve the Indemnifying Party of any
liability that the Indemnifying Party might have, except to the extent that such
failure prejudices the Indemnifying Party's ability to defend such Claim. The
Indemnifying Party shall have the right to defend against such liability or
assertion in which event the Indemnifying Party shall give written notice
to the Indemnified Party of acceptance of the defense of such Claim and the
identity of counsel selected by the Indemnifying Party. Until such time as
Indemnifying Party provides such written notice of acceptance of the defense of
such Claim, the Indemnified Party shall defend such Claim, at the expense of
the Indemnifying Party, subject to any right of the Indemnifying Party, to
seek reimbursement for the costs of such defense in the event that it is
determined that Indemnifying Party had no obligation to indemnify the
Indemnified Party for

                                 83
<PAGE>
 
such Claim. The Indemnifying Party shall have exclusive right to control and
conduct the defense and settlement of any such Claims subject to consultation
with the Indemnified Party. The Indemnifying Party shall not be liable for any
settlement by the Indemnified Party unless such Indemnifying Party has approved
such settlement in advance and agrees to be bound by the agreement incorporating
such settlement. At any time, an Indemnified Party shall have the right to
refuse a compromise or settlement and, at such refusing Party's cost, to take
over such defense; provided that in such event the Indemnifying Party shall not
                   -------- 
be responsible for, nor shall it be obligated to indemnify the relevant
Indemnified Party against, any cost or liability in excess of such refused
compromise or settlement. With respect to any defense accepted by the
Indemnifying Party, the relevant Indemnified Party shall be entitled to
participate with the Indemnifying Party in such defense if the Claim requests
equitable relief or other relief that could affect the rights of the Indemnified
Party and also shall be entitled to employ separate counsel for such defense at
such Indemnified Party's expense. If the Indemnifying Party does not accept the
defense of any indemnified Claim as provided above, the relevant Indemnified
Party shall have the right to employ counsel for such defense at the expense of
the Indemnifying Party. Each Party agrees to cooperate and to cause its
employees and agents to cooperate with the other Party in the defense of any
such Claim and the relevant records of each Party shall be available to the
other Party with respect to any such defense, subject to the restrictions and
limitations set forth in ARTICLE XX.
                         ----------


                                 ARTICLE XXVI
                            LIMITATION OF LIABILITY
   
     26.1 LIMITED RESPONSIBILITY. Each Party shall be responsible only for
service(s) and facility(ies) which are provided by that Party, its authorized
agents, subcontractors, or others retained by such parties, and neither Party
shall bear any responsibility for the services and facilities provided by the
other Party, its Affiliates, agents, subcontractors, or other persons retained
by such parties. No Party shall be liable for any act or omission of another
Telecommunications Carrier (other than an Affiliate) providing a portion of a
service.

     26.2 APPORTIONMENT OF FAULT. In the case of any Loss arising from the
negligence or willful misconduct of both Parties, each Party shall bear, and its
obligation shall be limited to, that portion of the resulting expense caused by
its negligence or misconduct of such Party's Affiliates, agents, contractors or
other persons acting in concert with it.

     26.3 LIMITATION OF DAMAGES. Except for indemnity obligations under ARTICLE
                                                                        -------
XXV, each Party's liability to the other Party for any Loss relating to or
---
arising out of any negligent act or omission in its performance of this
Agreement, whether in contract, tort or otherwise, shall be limited to the
total amount properly charged to the other Party by such negligent or breaching
Party for the service(s) or function(s) not performed or improperly
performed. Notwithstanding the foregoing, in cases involving any Claim for a
Loss associated with the installation, provision, termination, maintenance,
repair or restoration of an individual Network Element or

                                 84
<PAGE>
 
Combination or a Resale Service provided for a specific Customer of the other
Party, the negligent or breaching Party's liability shall be limited to the
greater of: (i) the total amount properly charged to the other Party for the
service or function not performed or improperly performed and (ii) the amount
such negligent or breaching Party would have been liable to its Customer if the
comparable retail service was provided directly to its Customer.

     26.4 LIMITATIONS IN TARIFFS. Each Party may, in its sole discretion,
provide in its tariffs and contracts with its Customers or third parties that
relate to any service, product or function provided or contemplated under this
Agreement that, to the maximum extent permitted by Applicable Law, such Party
shall not be liable to such Customer or third party for (i) any Loss relating
to or arising out of this Agreement, whether in contract, tort or otherwise,
that exceeds the amount such Party would have charged the applicable person for
the service, product or function that gave rise to such Loss and (ii) any
Consequential Damages (as defined in Section 26.5). To the extent a Party elects
not to place in its tariffs or contracts such limitation(s) of liability, and
the other Party incurs a Loss as a result thereof, such Party shall indemnify
and reimburse the other Party for that portion of the Loss that would have been
limited had the first Party included in its tariffs and contracts the
limitation(s) of liability that such other Party included in its own tariffs at
the time of such Loss.

     26.5 CONSEQUENTIAL DAMAGES. In no event shall either Party have any
liability whatsoever to the other Party for any indirect, special,
consequential, incidental or punitive damages, including loss of anticipated
profits or revenue or other economic loss in connection with or arising from
anything said, omitted or done hereunder (collectively, "CONSEQUENTIAL
DAMAGES"), even if the other Party has been advised of the possibility of such
damages; provided that the foregoing shall not limit a Party's obligation under
         --------
SECTION 25.1 to indemnify, defend and hold the other Party harmless against any
------------
amounts payable to a third person, including any losses, costs, fines,
penalties, criminal or civil judgments or settlements, expenses (including
attorneys' fees) and Consequential Damages of such third person.

     26.6 REMEDIES. Except as expressly provided herein, no remedy set forth in
this Agreement is intended to be exclusive and each and every remedy shall be
cumulative and in addition to any other rights or remedies now or hereafter
existing under applicable law or otherwise.

                                 ARTICLE XXVII
                                    BILLING
                                        
     27.1 BILLING.

          27.1.1 Each Party will bill all applicable charges, at the rates
set forth herein, in the Pricing Schedule and as set forth in applicable
tariffs or contracts referenced herein, for the services provided by that Party
to the other Party in accordance with this ARTICLE XXVII and the Implementation
                                           -------------  
Plan.

                                 85
<PAGE>
 
          27.1.2 The Parties agree that in order to ensure the proper
performance and integrity of the entire billing process, each Party will be
responsible and accountable for transmitting to the other Party an accurate and
current bill. Each Party agrees to implement control mechanisms and procedures
to render a bill that accurately reflects the services ordered and used by the
other Party.

     27.2 RECORDING. To the extent technically feasible, the Parties shall
record all available call detail information associated with calls originated or
terminated to the other Party, in accordance with the Implementation Plan and as
specifically required herein.

     27.3 PAYMENT OF CHARGES. Subject to the terms of this Agreement, Focal and
Ameritech will pay each other within forty-five (45) calendar days from the date
of an invoice (the "BILL DUE DATE"). If the Bill Due Date is on a day other than
a Business Day, payment will be made on the next Business Day. Payments shall be
made in U.S. Dollars via electronic funds transfer ("EFT") to the other 
Party's bank account. Within thirty (30) days of the Effective Date, /18/ the
                                                                      --
Parties shall provide each other the name and address of its bank, its account
and routing number and to whom payments should be made payable. If such banking
information changes, each Party shall provide the other Party at least sixty
(60) days' written notice of the change and such notice shall include the new
banking information. If a Party receives multiple invoices which are payable on
the same date, such Party may remit one payment for the sum of all amounts
payable to the other Party's bank. Each Party shall provide the other Party with
a contact person for the handling of payment questions or problems.

     27.4 LATE PAYMENT CHARGES. If either Party fails to remit payment for any
charges for services by the Bill Due Date, or if a payment or any portion of
a payment is received by either Party after the Bill Due Date, or if a payment
or any portion of a payment is received in funds which are not immediately
available to the other Party as of the Bill Due Date, then a late payment
penalty shall be assessed. The portion of the payment not received by the Bill
Due Date shall accrue interest as provided in SECTION 27.6. In no event,
                                              ------------
however, shall interest be assessed on any previously assessed late payment
charges.

     27.5 ADJUSTMENTS. 

          27.5.1  A Party shall promptly reimburse or credit the other Party for
any charges that should not have been billed to the other Party as provided 
in this Agreement. Such reimbursements shall be set forth in the appropriate
section of the invoice.

          27.5.2  A Party shall bill the other Party for any charges that should
have been billed to the other Party as provided in this Agreement, but have not
been billed to the other

______________________

/18/ Since the terms of this Agreement are the result of Focal's adoption under
 --
     Section 252(i) of the Act of the Teligent Agreement, the Parties agree that
     the term "Effective Date", for purposes of this SECTION 27.3, shall mean
                                                     ------------
     February 10, 1999.

                                      86
<PAGE>
 
Party ("UNDERBILLED CHARGES"); provided, however, that, except as provided in
                               --------  -------
ARTICLE XXVIII, the Billing Party shall not bill for Underbilled Charges which
--------------
were incurred more than one (1) year prior to the date that the Billing Party
transmits a bill for any Underbilled Charges. Notwithstanding the foregoing,
Focal shall not be liable for any Underbilled Charges for which Customer Usage
Data was not furnished by Ameritech to Focal within ten (10) months of the date
such usage was incurred.

     27.6 INTEREST ON UNPAID AMOUNTS. Any undisputed amounts not paid when due
shall accrue interest from the date such amounts were due at the lesser of (i)
one and one-half percent (1 1/2%) per month or (ii) the highest rate of
interest that may be charged under Applicable Law, compounded daily from the
number of days from the Bill Due Date to and including the date that payment is
actually made.


                                ARTICLE XXVIII
                        AUDIT RIGHTS, DISPUTED AMOUNTS
                            AND DISPUTE RESOLUTION
                                        
     28.1 AUDIT RIGHTS.
           
          28.1.1 Subject to the restrictions set forth in ARTICLE XX and except
                                                          ----------
as may be otherwise specifically provided in this Agreement, a Party ("AUDITING
PARTY") may audit the other Party's ("AUDITED PARTY") books, records, data and
other documents, as provided herein, once each Contract Year for the purpose of
evaluating the accuracy of Audited Party's billing and invoicing. The scope of
the audit shall be limited to the services provided and purchased by the Parties
and the associated charges, books, records, data and other documents relating
thereto for the period which is the shorter of (i) the period subsequent to the
last day of the period covered by the Audit which was last performed (or if no
audit has been performed, the Effective Date /19/ and (ii) the twenty-four (24)
                                              --
month period immediately preceding the date the Audited Party received notice of
such requested audit. Such audit shall begin no fewer than thirty (30) days
after Audited Party receives a written notice requesting an audit and shall be
completed no later than thirty (30) days after the start of such audit. Such
audit shall be conducted by an independent auditor acceptable to both Parties.
The Parties shall select an auditor by the thirtieth day following Audited
Party's receipt of a written audit notice. Auditing Party shall cause the
independent auditor to execute a nondisclosure agreement in a form agreed upon
by the Parties. Notwithstanding the foregoing, an Auditing Party may audit
Audited Party's books, records and documents more than once during any Contract
Year if the previous audit found previously uncorrected net variances or errors
in invoices in Audited Party's favor with an aggregate value

______________________

/19/ Since the terms of this Agreement are the result of Focal's adoption under
 --
     Section 252(i) of the Act of the Teligent Agreement, the Parties agree that
     the term "Effective Date", for purposes of this SECTION 28.1.1, shall mean
                                                     --------------
     February 10, 1999.

                                      87
<PAGE>
 
of at least two percent (2%) of the amounts payable by Auditing Party for
audited services provided during the period covered by the audit.

          28.1.2 Each audit shall be conducted on the premises of Audited Party
during normal business hours. Audited Party shall cooperate fully in any such
audit, providing the independent auditor reasonable access to any and all
appropriate Audited Party employees and books, records and other documents
reasonably necessary to assess the accuracy of Audited Party's bills. No Party
shall have access to the data of the other Party, but shall rely upon summary
results provided by the independent auditor. Audited Party may redact from the
books, records and other documents provided to the independent auditor any
confidential Audited Party information that reveals the identity of other
Customers of Audited Party. Each Party shall maintain reports, records and data
relevant to the billing of any services that are the subject matter of this
Agreement for a period of not less than twenty-four (24) months after creation
thereof, unless a longer period is required by Applicable Law.

          28.1.3 If any audit confirms any undercharge or overcharge, then
Audited Party shall (i) for any overpayment promptly correct any billing error,
including making refund of any overpayment by Auditing Party in the form of a
credit on the invoice for the first full billing cycle after the Parties have
agreed upon the accuracy of the audit results and (ii) for any undercharge
caused by the actions of or failure to act by the Audited Party, immediately
compensate Auditing Party for such undercharge, in each case with interest at
the lesser of (x) one and one-half (1 1/2%) percent per month and (y) the
highest rate of interest that may be charged under Applicable Law, compounded
daily, for the number of days from the date on which such undercharge or
overcharge originated until the date on which such credit is issued or payment
is made and available, as the case may be. Notwithstanding the foregoing, Focal
shall not be liable for any Underbilled Charges for which Customer Usage Data
was not furnished by Ameritech to Focal within ten (10) months of the date such
usage was incurred.

          28.1.4 Audits shall be at Auditing Party's expense, subject to
reimbursement by Audited Party in the event that an audit finds, and the Parties
subsequently verify, adjustment in the charges or in any invoice paid or payable
by Auditing Party hereunder by an amount that is, on an annualized basis,
greater than two percent (2%) of the aggregate charges for the audited services
during the period covered by the audit.

           28.1.5 Any Disputes concerning audit results shall be referred to the
Parties' respective responsible personnel for informal resolution. If these
individuals cannot resolve the Dispute within thirty (30) days of the referral,
either Party may request in writing that an additional audit shall be conducted
by an independent auditor acceptable to both Parties, subject to the
requirements set out in SECTION 28.1.1. Any additional audit shall be at the
                        -------------- 
requesting Party's expense.

                                      88
<PAGE>
 
     28.2 DISPUTED AMOUNTS.

          28.2.1 If any portion of an amount due to a Party (the "BILLING
PARTY") under this Agreement is subject to a bona fide dispute between the
Parties, the Party billed (the "NON-PAYING PARTY") shall, prior to the Bill Due
Date, give written notice to the Billing Party of the amounts it disputes
("DISPUTED AMOUNTS") and include in such written notice the specific details and
reasons for disputing each item; provided, however, a failure to provide such
                                 --------  -------
notice by that date shall not preclude a Party from subsequently challenging
billed charges. The Non-Paying Party shall pay when due all undisputed amounts
to the Billing Party. Notwithstanding the foregoing, except as provided in
SECTION 28.1, a Party shall be entitled to dispute only those charges for which
------------
the Bill Due Date was within the immediately preceding twelve (12) months of the
date on which the other Party received notice of such Disputed Amounts.

          28.2.2 If the Non-Paying Party disputes a charge and does not pay such
Disputed Amounts by the Bill Due Date, such Disputed Amounts shall be subject to
late payment charges as set forth in SECTION 27.4. If the Non-Paying Party
                                     ------------
disputes charges and the dispute is resolved in favor of such Non-Paying Party,
the Billing Party shall credit the invoice of the Non-Paying Party for the
amount of the Disputed Amounts along with any applicable late payment charges
assessed no later than the second Bill Due Date after the resolution of the
Dispute. Accordingly, if a Non-Paying Party disputes charges and the dispute is
resolved in favor of the Billing Party, the Non-Paying Party shall pay the
Billing Party the amount of the Disputed Amounts and any associated late payment
charges assessed no later than the second Bill Due Date after the resolution of
the Dispute. In no event, however, shall any late payment charges be assessed on
any previously assessed late payment charges.

          28.2.3 If the Parties are unable to resolve the issues related to the
Disputed Amounts in the normal course of business within sixty (60) days after
delivery to the Billing Party of notice of the Disputed Amounts, each of the
Parties shall appoint a designated representative who has authority to settle
the Dispute and who is at a higher level of management than the persons with
direct responsibility for administration of this Agreement. The designated
representatives shall meet as often as they reasonably deem necessary in order
to discuss the Dispute and negotiate in good faith in an effort to resolve such
Dispute. The specific format for such discussions will be left to the discretion
of the designated representatives, however all reasonable requests for relevant
information made by one Party to the other Party shall be honored.

          28.2.4 If the Parties unable to resolve issues related to the Disputed
Amounts within forty-five (45) days after the Parties' appointment of designated
representatives pursuant to SECTION 28.3, then either Party may file a complaint
                            ------------
with the Commission to resolve such issues or proceed with any other remedy
pursuant to law or equity. The Commission or the FCC may direct payment of 
any or all Disputed Amounts (including any accrued interest) thereon or
additional amounts awarded plus applicable late fees, to be paid to either
Party.

                                 89
<PAGE>
 
          28.2.5 The Parties agree that all negotiations pursuant to this
SECTION 28.2 shall remain confidential in accordance with ARTICLE XX and shall
------------                                              ----------
be treated as compromise and settlement negotiations for purposes of the Federal
Rules of Evidence and state rules of evidence.

     28.3 DISPUTE ESCALATION AND RESOLUTION. Except as otherwise provided
herein, any dispute, controversy or claim (individually and collectively, a
"DISPUTE") arising under this Agreement shall be resolved in accordance with the
procedures set forth in this SECTION 28.3. In the event of a Dispute between the
                             ------------
Parties relating to this Agreement and upon the written request of either Party,
each of the Parties shall appoint a designated representative who has authority
to settle the Dispute and who is at a higher level of management than the
persons with direct responsibility for administration of this Agreement. The
designated representatives shall meet as often as they reasonably deem necessary
in order to discuss the Dispute and negotiate in good faith in an effort to
resolve such Dispute. The specific format for such discussions will be left to
the discretion of the designated representatives, however, all reasonable
requests for relevant information made by one Party to the other Party shall be
honored. If the Parties are unable to resolve issues related to a Dispute within
thirty (30) days after the Parties' appointment of designated representatives as
set forth above, the Parties shall attempt in good faith to address any default
or resolve any Dispute according to the rules, guidelines or regulations of the
Commission (and any procedures available to a Telecommunications provider under
the Michigan Telecommunications Act). Nowithstanding the foregoing, in no event
shall the Parties permit the pending of a Dispute to disrupt service to any
Focal Customer or Ameritech Customer.

     28.4 EQUITABLE RELIEF. Nowithstanding the foregoing, this ARTICLE XXVIII
                                                               --------------
shall not be construed to prevent either Party from seeking and obtaining
temporary equitable remedies, including temporary restraining orders, if, in its
judgment, such action is necessary to avoid irreparable harm. Despite any such
action, the Parties will continue to participate in good faith in the dispute
resolution procedures described in this ARTICLE XXVIII.
                                        --------------

                                 ARTICLE XXIX
                              REGULATORY APPROVAL

     29.1 COMMISSION APPROVAL.

     The Parties understand and agree that this Agreement will be filed with the
Commission for approval by such Commission (or the FCC if the Commission fails
to act) pursuant to Section 252 of the Act. Each Party agrees that this
Agreement is satisfactory to them as an agreement under Sections 251 and 252
of the Act. Each Party agrees to fully support approval of this Agreement by the
Commission (or the FCC) under Section 252 of the Act without modification; 
provided, however, that each Party may exercise its right to judicial review
--------  -------
under Section 252(e)(6) of the Act, or any other available remedy at law or
equity, with respect to any matter included herein by arbitration under the Act
over the objection of such Party. If the

                                 90
<PAGE>
 
Commission, the FCC or any court rejects any portion of this Agreement, the
Parties agree to meet and negotiate in good faith to arrive at a mutually
acceptable modification of the rejected portion and related provisions; provided
                                                                        --------
that such rejected portion shall not affect the validity of the remainder of
this Agreement. The Parties acknowledge that nothing in this Agreement shall
limit a Party's ability, independent of such Party's agreement to support and
participate in the approval of this Agreement, to assert public policy issues
relating to the Act.

     29.2 TARIFFS. If either Party is required by any governmental authority to
file a tariff or make another similar filing to implement any provision of this
Agreement (other than a tariff filed by a Party that generally relates to one or
more services provided under this Agreement but not specifically to Focal or
Ameritech) (an "AMERITECH/FOCAL INTERCONNECT TARIFF"), such Party shall (i)
consult with the other Party reasonably in advance of such filing about the form
and substance of such Ameritech/Focal Interconnect Tariff, (ii) provide to such
other Party its proposed Ameritech/Focal Interconnect Tariff and obtain such
other Party's agreement on the form and substance of such Ameritech/Focal
Interconnect Tariff prior to such filing, and (iii) take all steps reasonably
necessary to ensure that such Ameritech/Focal Interconnect Tariff or other
filing imposes obligations upon such Party that are as close as possible to
those provided in this Agreement and preserves for such other Party the full
benefit of the rights otherwise provided in this Agreement. If, subsequent to
the effective date of any such Ameritech/Focal Interconnect Tariff, a Party is
no longer required to file tariffs with the Commission or the FCC, either
generally or for specific services, the Parties agree to modify this Agreement
to reflect herein the relevant and consistent terms and conditions of such
Ameritech/Focal Interconnect Tariffs as of the date on which the requirement to
file such Ameritech/Focal Interconnect Tariffs was lifted. Nothing in this
SECTION 29.2 shall be construed to grant a Party any right to review any tariff
------------
filing of the other Party other than the Ameritech/Focal Interconnection Tariff,
other than as provided under Applicable Law.

     29.3 AMENDMENT OR OTHER CHANGES TO THE ACT; RESERVATION OF RIGHTS. The
Parties acknowledge that the respective rights and obligations of each Party as
set forth in this Agreement are based on the text of the Act and the rules and
regulations promulgated thereunder by the FCC and the Commission as of the
Effective Date. In the event of any amendment of the Act, or any final and
nonappealable legislative, regulatory, judicial order, rule or regulation or
other legal action that revises or reverses the Act, the FCC's First Report and
Order in CC Docket Nos. 96-98 and 95-185 or any applicable Commission order or
arbitration award purporting to apply the provisions of the Act (individually
and collectively, an "AMENDMENT TO THE ACT"), either Party may by providing
written notice to the other Party require that the affected provisions be
renegotiated in good faith and this Agreement be amended accordingly to reflect
the pricing, terms and conditions of each such Amendment to the Act relating to
any of the provisions in this Agreement. If any such amendment to this Agreement
affects any rates or charges of the services provided hereunder, each Party
reserves its rights and remedies with respect to the collection of such rates or
charges on a retroactive basis, including the right to seek a surcharge before
the applicable regulatory authority.

                                 91
<PAGE>
 
     29.4 REGULATORY CHANGES. If any final and nonappealable legislative,
regulatory, judicial or other legal action (other than an Amendment to the Act,
which is provided for in SECTION 29.3) materially affects the ability of a Party
                         ------------
to perform any material obligation under this Agreement, a Party may, on thirty
(30) days' written notice (delivered not later than thirty (30) days following
the date on which such action has become legally binding and has otherwise
become final and nonappealable), require that the affected provision(s) be
renegotiated, and the Parties shall renegotiate in good faith such mutually
acceptable new provision(s) as may be required; provided that such affected
                                                --------
provisions shall not affect the validity of the remainder of this Agreement.

     29.5 PROXY RATES. In the event the initial rates under this Agreement are
"proxy rates" established by the FCC or the Commission, the Parties are to
substitute rates later established by the FCC or Commission under procedures
consistent with the Act and any Order of the FCC or Commission.

                                  ARTICLE XXX
                                 MISCELLANEOUS
                                        
     30.1 AUTHORIZATION.

          30.1.1 Ameritech Services, Inc. is a corporation duly organized,
validly existing and in good standing under the laws of the State of Delaware.
Ameritech Information Industry Services, a division of Ameritech Services, Inc.
has full power and authority to execute and deliver this Agreement and to
perform the obligations hereunder on behalf of and as agent for Ameritech
Michigan.

          30.1.2 Focal is a corporation duly organized, validly existing and in
good standing under the laws of the State of Delaware and has full power and
authority to execute and deliver this Agreement and to perform its obligations
hereunder. Focal represents and warrants to Ameritech that it has been certified
as an LEC by the Commission and is authorized to provide in the State of
Delaware the services it has contracted to provide herein.

     30.2 DESIGNATION OF AFFILIATE. Each Party may without the consent of the
other Party fulfill its obligations under this Agreement by itself or may cause
its Affiliates to take some or all of such actions to fulfill such obligations.
Upon such designation, the Affiliate shall become a primary obligor hereunder
with respect to the delegated matter, but such designation shall not relieve the
designating Party of its obligations as primary obligor hereunder. Any Party
which elects to perform its obligations through an Affiliate shall cause its
Affiliate to take all action necessary for the performance hereunder of such
Party's obligations. Each Party represents and warrants that if an obligation
under this Agreement is to be performed by an Affiliate, such Party has the
authority to cause such Affiliate to perform such obligation and such Affiliate
will have the resources required to accomplish the delegated performance.

                                      92
<PAGE>
 
     30.3 SUBCONTRACTING. Either Party may subcontract the performance of its
obligation under this Agreement without the prior written consent of the other
Party; provided, however, that the Party subcontracting such obligation shall
       --------  -------
remain fully responsible for the performance of such obligation and be solely
responsible for payments due its subcontractors.

     30.4 INDEPENDENT CONTRACTOR. Each Party shall perform services hereunder as
an independent contractor and nothing herein shall be construed as creating any
other relationship between the Parties. Each Party and each Party's contractor
shall be solely responsible for the withholding or payment of all applicable
federal, state and local income taxes, social security taxes and other payroll
taxes with respect to their employees, as well as any taxes, contributions or
other obligations imposed by applicable state unemployment or workers'
compensation acts. Each Party has sole authority and responsibility to hire,
fire and otherwise control its employees.

     30.5 FORCE MAJEURE. No Party shall be responsible for delays or failures in
performance of any part of this Agreement (other than an obligation to make
money payments) resulting from acts or occurrences beyond the reasonable control
of such Party, including acts of nature, acts of civil or military authority,
any law, order, regulation, ordinance of any government or legal body,
embargoes,epidemics, terrorist acts, riots, insurrections, fires, explosions,
earthquakes, nuclear accidents, floods, work stoppages, equipment failures,
power blackouts, volcanic action, other major environmental disturbances,
unusually severe weather conditions, inability to secure products or services of
other persons or transportation facilities or acts or omissions of
transportation carriers (individually or collectively, a "FORCE MAJEURE EVENT")
or delays caused by the other Party or any other circumstances beyond the
Party's reasonable control. If a Force Majeure Event shall occur, the Party
affected shall give prompt notice to the other Party of such Force Majeure Event
specifying the nature, date of inception and expected duration of such Force
Majeure Event, whereupon such obligation or performance shall be suspended to
the extent such Party is affected by such Force Majeure Event during the
continuance thereof or be excused from such performance depending on the nature,
severity and duration of such Force Majeure Event (and the other Party shall
likewise be excused from performance of its obligations to the extent such
Party's obligations relate to the performance so interfered with). The affected
Party shall use its reasonable efforts to avoid or remove the cause of
nonperformance and the Parties shall give like notice and proceed to perform
with dispatch once the causes are removed or cease. Notwithstanding the
preceding, no delay or other failure to perform shall be excused pursuant to
this SECTION 30.5 (i) by the acts or omission of a Party's subcontractors,
     ------------
materialmen, suppliers or other third persons providing products or services to
such Party unless such acts or omissions are themselves the product of a Force
Majeure Event, and unless such delay or failure and the consequences thereof are
beyond the control and without the fault or negligence of the Party claiming
excusable delay or other failure to perform, or (ii) if such Party fails to
implement any steps taken to mitigate the effects of a Force Majeure Event e.g.,
                                                                           ----
disaster recovery plans) in a nondiscriminatory manner during the period
performance is impaired.

     30.6 GOVERNING LAW. For all claims under this Agreement that are based upon
issues within the jurisdiction (primary or otherwise) of the FCC, the exclusive
jurisdiction and remedy

                                      91
        
<PAGE>
 
for all such claims shall be as provided for by the FCC and the Act. For all
claims under this Agreement that are based upon issues within the jurisdiction
(primary or otherwise) of the Commission, the exclusive jurisdiction for all
such claims shall be with such Commission, and the exclusive remedy for such
claims shall be as provided for by such Commission. In all other respects, this
Agreement shall be governed by the domestic laws of the State of Michigan
without reference to conflict of law provisions; provided, however, that the
                                                 --------  -------
Parties shall consult with each other and attempt to agree on a common state law
to govern an issue that affects each of the Regional Interconnection Agreements
and such issue is not particular to a specific State's law.

     30.7 TAXES.

          30.7.1 Each Party purchasing services hereunder shall pay or otherwise
be responsible for all federal, state, or local sales, use, excise, gross
receipts, transaction or similar taxes, fees or surcharges levied against or
upon such purchasing Party (or the providing Party when such providing Party is
permitted to pass along to the purchasing Party such taxes, fees or surcharges),
except for any tax on either Party's corporate existence, status or income.
Whenever possible, these amounts shall be billed as a separate item on the
invoice. To the extent a sale is claimed to be for resale, the purchasing Party
shall furnish the providing Party a proper resale tax exemption certificate as
authorized or required by statute or regulation by the jurisdiction providing
said resale tax exemption. Failure to timely provide said resale tax exemption
certificate will result in no exemption being available to the purchasing Party
for any changes invoiced prior to the date such exemption certificate is
furnished. To the extent that a Party includes gross receipts taxes in any of
the charges or rates of services provided hereunder, no additional gross
receipts taxes shall be levied against or upon the purchasing Party.
 
          30.7.2 The Party obligated to pay any such taxes may contest the same
in good faith, at its own expense, and shall be entitled to the benefit of any
refund or recovery, provided that such contesting Party shall not permit any
                    --------
lien to exist on any asset of the other Party by reason of such contest. The
Party obligated to collect and remit shall cooperate in any such contest by the
other Party. As a condition of contesting any taxes due hereunder, the
contesting Party agrees to be liable and indemnify and reimburse the other Party
for any additional amounts that may be due by reason of such contest, including
any interest and penalties.

     30.8 NON-ASSIGNMENT. Neither Party may assign or transfer (whether by
operation of law or otherwise) this Agreement (or any rights or obligations
hereunder) to a third person without the prior written consent of the other
Party; provided that each Party may assign or transfer this Agreement to an
       --------
Affiliate in accordance with SECTION 30.2 by providing prior written notice to
                             ------------ 
the other Party of such assignment or transfer; provided, further, that such
                                                --------  -------
assignment is not inconsistent with Applicable Law or the terms and conditions
of this Agreement. Any attempted assignment or transfer that is not permitted is
void ab initio. Without limiting the generality of the foregoing, this Agreement
     -- ------
shall be binding upon and shall inure to the benefit of the Parties' respective
successors and assigns and the assigning Party will remain liable for the
performance of any assignee.

                                      94
<PAGE>
 
     30.9  NON-WAIVER. Failure of either Party to insist on performance of any
term or condition of this Agreement or to exercise any right or privilege
hereunder shall not be construed as a continuing or future waiver of such term,
condition, right or privilege.

     30.10 NOTICES. Notices given by one Party to the other Party under this
Agreement shall be in writing (unless specifically provided otherwise herein)
and unless otherwise specifically required by this Agreement to be delivered to
another representative or point of contact, shall be (a) delivered personally,
(b) delivered by express delivery service, (c) mailed, certified mail or first
class U.S. mail postage prepaid, return receipt requested or (d) delivered by
telecopy; provided that a confirmation copy is sent by the method described in
          --------
(a), (b) or (c) of this SECTION 30.10, to the following addresses of the
                        -------------
Parties:


          To Focal:
          
          Focal Communications Corporation of Michigan
          200 N. LaSalle Street
          Suite 800
          Chicago, Illinois 60601
          Attn: Director Regulatory Affairs
          
          To Ameritech:
          
          Ameritech Information Industry Services
          350 North Orleans, Floor 3
          Chicago, IL 60654
          Attn: Vice President - Network Providers 
          Facsimile: (312)335-2927
          
          with a copy to:
          
          Ameritech Information Industry Services
          350 North Orleans, Floor 5
          Chicago, IL 60654
          Attn: Vice President and General Counsel
          Facsimile: (312)245-0254

or to such other address as either Party shall designate by proper notice.
Notices will be deemed given as of the earlier of (i) the date of actual
receipt, (ii) the next business day when notice is sent via express mail or
personal delivery, (iii) three (3) days after mailing in the case of first class
or certified U.S. mail or (iv) on the date set forth on the confirmation in the
case of telecopy.

                                      95
<PAGE>
 
     30.11 PUBLICITY AND USE OF TRADEMARKS OR SERVICE MARKS.

Neither Party nor its subcontractors or agents shall use the other Party's
trademarks, service marks, logos or other proprietary trade dress in any
advertising, press releases, publicity matters or other promotional materials
without such Party's prior written consent, except as permitted by Applicable
Law.

     30.12 NONEXCLUSIVE DEALINGS.

This Agreement does not prevent either Party from providing or purchasing
services to or from any other person nor, except as provided in Section 2.52(i)
of the Act, does it obligate either Party to provide or purchase any services
not specifically provided herein.

     30.13 NO THIRD PARTY BENEFICIARIES; DISCLAIMER OF AGENCY. Except as may be
specifically set forth in this Agreement, this Agreement is for the sole benefit
of the Parties and their permitted assigns, and nothing herein express or
implied shall create or be construed to create any third-party beneficiary
rights hereunder. Nothing in this Agreement shall constitute a Party as a legal
representative or agent of the other Party, nor shall a Party have the right or
authority to assume, create or incur any liability or any obligation of any
kind, express or implied, against or in the name or on behalf of the other Party
unless otherwise expressly permitted by such other Party. No Party undertakes to
perform any obligation of the other Party, whether regulatory or contractual, or
to assume any responsibility for the management of the other Party's business.

     30.14 NO LICENSE. No license under patents, copyrights or any other
Intellectual Property right (other than the limited license to use consistent
with the terms, conditions and restrictions of this Agreement) is granted either
Party or shall be implied or arise by estoppel with respect to any transactions
contemplated under this Agreement.

     30.15 SURVIVAL. The Parties' obligations under this Agreement which by
their nature are intended to continue beyond the termination or expiration of
this Agreement shall survive the termination or expiration of this Agreement,
including ARTICLES XX, XXI, XXII, XXIII, XXV, AND XXVI, SECTIONS 3.9.4, 6.5,
          -----------  ---  ----  -----  ---      ----  --------------  ---
10.11.3, 16.15, 16.17, 19.5.3, 28.2, 28.3, 30.7, 30.11, AND 30.14 AND SCHEDULE
-------  -----  -----  ------  ----  ----  ----  -----      -----     --------
10.9.6.
------

      30.16 SCOPE OF AGREEMENT. This Agreement is intended to describe and
enable specific Interconnection and access to unbundled Network Elements and
compensation arrangements between the Parties. This Agreement does not obligate
either Party to provide arrangements not specifically provided herein. Except as
specifically contained herein or provided by the FCC or the Commission within
its lawful jurisdiction, nothing in this Agreement shall be deemed to affect any
access charge arrangement.

     30.17 COUNTERPARTS. This Agreement may be executed in any number of
counterparts, each of which shall be deemed an original; but such counterparts
shall together constitute one and the same instrument.

                                      96
<PAGE>
 
     30.18 ENTIRE AGREEMENT. The terms contained in this Agreement and any
Schedules, Exhibits, tariffs and other documents or instruments referred to
herein, which are incorporated into this Agreement by this reference, constitute
the entire agreement between the Parties with respect to the subject matter
hereof, superseding all prior understandings, proposals and other
communications, oral or written. Specifically, the Parties expressly acknowledge
that the rates, terms and conditions of this Agreement shall supersede those
existing arrangements of the Parties, if any, set forth on SCHEDULE 30.18.
                                                           -------------- 
Neither Party shall be bound by any terms additional to or different from those
in this Agreement that may appear subsequently in the other Party's form
documents, purchase orders, quotations, acknowledgments, invoices or other
communications. This Agreement may only be modified by a writing signed by an
officer of each Party.


                                 ARTICLE XXXI
                             AMERITECH COLLOCATION
                                        
     31.1 PHYSICAL COLLOCATION.

     Focal shall provide to Ameritech Physical Collocation in the LEC Access
Equipment Room in Focal's Wire Centers for equipment necessary for
Interconnection (pursuant to ARTICLE III). Focal shall provide Ameritech
                             -----------
Collocation only for the purpose of such Interconnection.

     31.2 ELIGIBLE EQUIPMENT.

     Ameritech may Collocate equipment necessary for Interconnection of the same
type that it uses to provide total service access/20/ for Focal.
                                                  --

     31.3 TRANSMISSION FACILITY OPTIONS.

     Ameritech may either purchase transmission facilities (and any necessary
Cross-Connection) from Focal or provide its own transmission facilities and
terminate those transmission facilities in its equipment located in its
Collocation space at Focal's Premises.

     31.4 INTERCONNECTION POINTS AND CABLES.

     Focal shall:

     31.4.1 provide Ameritech an Interconnection point or points physically
accessible by both Ameritech and Focal, at which the fiber optic cable carrying
Ameritech's circuits can enter

______________

/20/  Total service access are access services purchased by Focal from Ameritech
 --                                                                            
      to provide switched or dedicated access to Focal Customers.

                                      97
<PAGE>
 
Focal's Premises; provided that Focal shall designate Interconnection Points as
                  --------
close as reasonably possible to Focal's Premises;

     31.4.2 provide at least two (2) such Interconnection points at Focal's
Premises at which there are at least two (2) entry points for Ameritech's cable
facilities, and at which space is available for new facilities in at least two
(2) of those entry points; and

     31.4.3 permit Ameritech Interconnection of copper or coaxial cable if such
Interconnection is first approved by the Commission.

     31.5   ALLOCATION OF COLLOCATION SPACE.

     31.5.1 Focal shall not be required to lease or construct additional space
in a Premises to provide Ameritech Physical Collocation when existing space in
such Premises has been exhausted.

     31.5.2 Ameritech will provide Focal a two (2)-year rolling forecast of its
requirements for Collocation that will be reviewed jointly on a yearly basis by
the Parties, in accordance with the planning processes agreed upon pursuant to
SCHEDULE 12.9.3. Focal will attempt to deliver Collocation pursuant to
---------------
Ameritech's forecasts to the extent that Collocation space is then available.

     31.5.3 The Parties expect that under normal conditions Focal will have
space available for Ameritech to interconnect with Focal for purposes of
terminating Local Traffic and IntraLATA Toll Traffic. However, should space not
be available, Focal will attempt to establish a POI at another mutually
agreeable Focal Wire Center which Focal determines has available space and
sufficient facilities for transporting, traffic between Focal Wire Centers at
rates, terms and conditions to be negotiated upon by the Parties. If an
alternative POI is not available in the LATA, the Parties will enter into good
faith negotiations to establish an alternative method for Ameritech to terminate
Local Traffic and IntraLATA Toll Traffic on Focal's network.

     31.6   SUBCONTRACTOR AND VENDOR APPROVAL. Focal shall allow Ameritech to
have an Focal-approved subcontractor install updates to Collocated equipment,
including software updates. Approval of such subcontractors by Focal shall be
based on the same criteria it uses in approving contractors for its own
purposes.

     31.7   DELIVERY OF COLLOCATED SPACE.

            31.7.1 Focal shall provide Ameritech with a single point of contact
for all inquiries regarding Collocation. If Ameritech needs to install
additional equipment in the LEC Access Equipment Room, Ameritech shall request
additional space for Collocation by delivering a written request to Focal. Each
request for Collocation shall include (i) the Premises in which Collocation is
requested, (ii) the interoffice transmission facilities Ameritech will require
for such space, (iii) the equipment to be housed in such space, and (iv) the
date on which Ameritech
<PAGE>
 
intends to initiate service from such space. Focal shall notify Ameritech in
writing within ten (10) Business Days of receiving Ameritech's request for
Collocation as to whether the requested space is available. If intraoffice
facilities will not be available for Collocation of initial service within three
(3) months after receipt of Ameritech's request for space pursuant to this
Section, then Focal shall provide written notification, within ten (10) Business
Days after the receipt of such request, as to when the intra office facilities
will be made available.

          31.7.2 Physical Collocation.

                 (a) If additional space for Physical Collocation is immediately
available at the time of Ameritech's request, Focal shall include in its notice
to Ameritech (i) the space to be provided and (ii) whether Focal can deliver the
space to Ameritech by the date set forth in SECTION 31.7.2(C).
                                            -----------------

                 (b) If Ameritech's requested Physical Collocation space is
available, Ameritech and Focal shall have an initial walkthrough of such
space within ten (10) Business Days after Focal confirms that the requested
space is available.

                 (c) Focal shall deliver to Ameritech the requested space on or
before the later of (i) one hundred twenty (120) days from Focal's receipt of
Ameritech's request for Collocation and (ii) such other reasonable date that the
Parties may agree upon if it is not feasible for Focal to deliver to Ameritech
such space within the foregoing intervals (such date of delivery referred to as
the "DELIVERY DATE").

                 (d) Physical Collocation will be subject to the additional
rules and regulations set forth in SCHEDULE 31.7.
                                   -------------

                 (e) After completion of construction, Focal and Ameritech will
complete an acceptance walkthrough of all Collocated space requested from Focal.
Exceptions that are noted during this acceptance walkthrough shall be corrected
by Focal within thirty (30) days after the walkthrough. Focal shall conduct a
root cause analysis of all exceptions identified. The correction of these
exceptions shall be at Focal's expense, subject to any change orders requested
by Ameritech.

                (f)  Ameritech shall also be entitled to credits for delays by
Focal in provisioning space for Collocation, and for the inability of Ameritech
to use equipment located in space provided for Collocation as a result of the
failure by Focal to comply with its obligations under this Agreement, pursuant
to terms and conditions agreed upon by the Implementation Team.

     31.8 PRICING. The prices charged to Ameritech for Collocation are set forth
on Exhibit PS-VII-A of the Pricing Schedule.

                                      99
<PAGE>
 
     31.9  BILLING.  Focal shall bill Ameritech for Collocation pursuant to the
requirements of ARTICLE XXVII to this Agreement.
                -------------

     31.10 ADDITIONAL REQUIREMENTS. The additional requirements set forth on
SCHEDULE 31.10 shall be applicable to Physical Collocation.
---------------                                            

     31.11 PROTECTION OF SERVICE AND PROPERTY.

           Both Parties shall exercise reasonable care to prevent harm or damage
to the other Party, its employees, agents or Customers, or their property. Both
Parties, their employees, agents, and representatives agree to take reasonable
and prudent steps to ensure the adequate protection of the other Party's
property and services, including:

           31.11.1  Ameritech and Focal shall restrict access to Ameritech
equipment, support equipment, systems, tools and data, or spaces which contain
or house Ameritech equipment enclosures, to Ameritech employees and other
authorized non-Ameritech personnel to the extent necessary to perform their
specific job function.
 
           31.11.2  Ameritech shall comply at all times with security and safety
procedures and existing requirements that are defined by Focal and communicated
to Ameritech.

           31.11.3  Focal shall allow Ameritech periodically to inspect or
observe spaces which house or contain Ameritech equipment or equipment
enclosures and furnish Ameritech with keys, entry codes, lock combinations, and
other materials or information which may be needed to gain entry into any
secured Ameritech space, subject to SECTION 31.11.2 and ARTICLE XX.
                                    ---------------     ----------

           31.11.4   Focal shall furnish to Ameritech a current written list of
Focal employees who Focal authorizes to enter Ameritech's Physical Collocation
space, with samples of the identifying credentials to be carried by such
persons.

           31.11.5  Focal shall secure external access to the Physical 
Collocation space on its Premises in the same or equivalent manner that Focal
secures external access to spaces that house Focal's equipment.

           31.11.6  Focal shall limit the keys used in its keying systems for
Ameritech's specific Physical Collocation space which contain or house Ameritech
equipment or equipment enclosures to its employees and representatives to
emergency access only. Ameritech shall further have the right, at its expense,
to have locks changed where deemed necessary for the protection and security of
such spaces, provided that Ameritech shall immediately provide Focal with such
             --------
new keys.

           31.11.7  Focal shall use its existig back-up and recovery plan in
accordance with its standard policies for the specific Wire Center.

                                      100
<PAGE>
 
      31.12 STANDARDS OF PERFORMANCE. Focal shall provide Collocation to
Ameritech in accordance with the service levels, procedures and intervals to be
agreed upon by the Implementation Team.

      IN WITNESS WHEREOF, the Parties have caused this Agreement to be executed
as of this 10th day of February 1999./21/
                                      --

FOCAL COMMUNICATIONS                       AMERITECH INFORMATION INDUSTRY
CORPORATION OF MICHIGAN                    SERVICES, A DIVISION OF AMERITECH
                                           SERVICES, INC., ON BEHALF OF AND AS
                                           AGENT FOR AMERITECH MICHIGAN


By: /s/ John R. Barnicle                   By: /s/ Karen S. Vessely
   --------------------------                 -----------------------------
Printed: John R. Barnicle                  Printed: Karen S. Vessely
        ---------------------                      ------------------------
Title:   C.O.O                             Title:   President
        ---------------------                      ------------------------

_____________________

/21/ This Agreement is the result of Focal's adoption of the terms and
 --
     conditions of that certain Interconnection Agreement under Sections 251 and
     252 of the Telecommunications Act of 1996 dated January 28, 1997 by and
     between Ameritech Michigan and Teligent, Inc. (the "Teligent Agreement").
     The Teligent Agreement was the result of Teligent's adoption of the terms
     and conditions of that certain Interconnection Agreement dated as of
     January 28, 1997 by and between Ameritech Michigan and AT&T Communications
     of Michigan, Inc. (the "AT&T Agreement"). This Agreement does not
     represent a voluntary or negotiated agreement under Section 252 of the
     Act but instead merely represents Ameritech's compliance with what Focal
     maintains is its rights under Section 252(i) of the Act. Filing and
     performance by Ameritech of this Agreement does not in any way constitute a
     waiver by Ameritech of its position of the illegality or unreasonableness
     of any rates, terms or conditions set forth in this Agreement, nor does it
     constitute a waiver by Ameritech of any rights and remedies it may have to
     seek review of this Agreement, the Teligent Agreement, or the AT&T
     Agreement, or to petition the Commission, other administrative body, or
     court for reconsideration or reversal of any determination made by the
     Commission in Cause No. U-11151/52 (the "AT&T Arbitration"), or seek 
     review in any way of any provisions included in this Agreement as a
     result of Focal's election under Section 252(i) of the Act. The Parties
     acknowledge that in no event shall any of the rates, terms or
     conditions set forth in this Agreement apply to any products or services
     purchased by Focal prior to the later of (i) the date the Commission
     approves this Agreement under Section 252(e) of the Act, and (ii) absent
     such Commission approval, the date this Agreement is deemed approved under
     Section 252(e)(4) of the Act.

     Neither Ameritech nor Focal's execution of this Agreement and compliance
     with the terms and conditions of this Agreement shall be construed as or is
     intended to be a concession or admission by either Party that any
     contractual provision required by the Commission in the AT&T Arbitration or
     any provision in this Agreement, the Teligent Agreement, or the AT&T
     Agreement complies with the rights and duties imposed by the Act, a
     decision by the FCC or the Commission, a decision of the courts, or other
     Applicable Law, and both Ameritech and Focal specifically reserve their
     respective full rights to assert and pursue claims arising from or related
     to this Agreement. Ameritech further contends that certain provisions of
     this Agreement including, without limitation. SECTIONS 9.1.2 and 9.2 are
                                                   --------------     ---       
     inconsistent with Ameritech's rights under the Act as interpreted by the
     United States Supreme Court in AT&T CORP. V. IOWA UTILITIES BD., 1999 WL
                                    --------------------------------
     24588 (Jan. 25, 1999). Ameritech reserves its rights, notwithstanding
     anything to the contrary in this Agreement, to exercise its rights as
     described in Footnote 9 of this Agreement, SECTION 29.3 of the Agreement,
                                                ------------
     and/or to seek appropriate legal and/or equitable relief. Further, in
     addition to any rights a Party may have under this Agreement including
     SECTION 29.3, if any provision in the AT&T Agreement is amended or modified
     ------------
     as result of any order or finding by the FCC, the Commission or a court of
     competent jurisdiction with respect to issues addressed in Case No. 97-
     60176 pending before the United States District Court of the Eastern
     District of Michigan (or any appeal thereof), this Agreement shall be
     deemed to be amended consistent with such order or finding, including the
     date such amendment is deemed effective.
<PAGE>
 
                                 SCHEDULE 1.2

                                  DEFINITIONS

     "9-1-1" means the services described in SECTION 3.9.
                                             ------------

     "9-1-1 CONTROL OFFICE SOFTWARE ENHANCEMENT CONNECTION CHARGE" is as
defined in SECTION 3.9.2(e) of this Agreement.
           ----------------

     "ACCESS TOLL CONNECTING TRUNKS" is as defined in SECTION 5.1.
                                                      -----------

     "ACT" means the Communications Act of 1934 (47 U.S.C. (S) 151 et seq.), as
                                                                   -------
amended by the Telecommunications Act of 1996, and as from time to time
interpreted in the duly authorized rules and regulations of the FCC or the
Commission having authority to interpret the Act within its stsate of
jurisdiction.

     "ADSL" OR "ASYMMETRICAL DIGITAL SUBSCRIBER LINE" means a transmission
technology which transmits an asymmetrical digital signal using one of a variety
line of codes.

     "ADVANCED INTELLIGENT NETWORK" OR "AIN" is a network functionality that
permits specific conditions to be programmed into a switch which, when met,
directs the switch to suspend call processing and to receive special
instructions for further call handling instructions in order to enable carriers
to offer advanced features and services.

     "AFFILIATE" is As Defined in the Act.

     "AMA" means the Automated Message Accounting structure inherent in switch
technology that initially records telecommunication message information. AMA
format is contained in the Automated Message Accounting document, published by
Bellcore as GR-1100-CORE which defines the industry standard for message
recording.
          
     "APPLICABLE LAWS" is as defined in SECTION 19.2.
                                        -------------

     "ARBITRATOR" is the person selected by the Parties to serve as Arbitrator
for any dispute submitted to arbitration pursuant to the dispute resolution
process.

     "AS DEFINED IN THE ACT" means as specifically defined by the Act and as
from time to time interpreted in the duly authorized rules and regulations of
the FCC or the Commission.

     "AS DESCRIBED IN THE ACT" means as described in or required by the Act and
as from time to time interpreted in the duly authorized rules and regulations of
the FCC or the Commission.

     "AUTOMATIC LOCATION IDENTIFICATION" OR "ALI" means a feature by which the
service address associated with the calling party's listed telephone number
identified by ANI as defined

                                 Sch. 1.2 - 1
<PAGE>
 
herein, is forwarded to the PSAP for display. Additional telephones with the 
same number calling party's including secondary locations and off-premise 
extensions will be identified with the service address of the calling party's 
listed number.

     "AUTOMATIC NUMBER IDENTIFICATION" or "ANI" means a Feature Group D 
signaling parameter which refers to the number transmitted through a network 
identifying the billing number of a calling party. With respect to 9 1 1 and E9
1 1, "ANI" means a feature by which the calling party's telephone number is 
automatically forwarded to the E9-1-1 Control Office and to the PSAP display and
transfer office

     "AUTOMATIC ROUTE SELECTION" or "ARS" means a service feature associated 
with a specific grouping of lines that provides for automatic selection of the 
least expensive or most appropriate transmission facility for each call based on
criteria programmed into the system.

     "BELLCORE" means Bell Communications Research, Inc.

     "BILL DATE" means the date that a bill is issues by a party.

     "BINDING FORECAST" is as defined in SECTION 19.5.3.
                                         --------------   

     "BLV/BLVI TRAFFIC" means an operator service call in which the caller 
inquires as to the busy status of or requests an interruption of a call on 
another Customer's Telephone Exchange Service line.

     "BUSINESS DAY" means a day on which banking institutions are required to be
open for business in Chicago, Illinois.

     "BONA FIDE REQUEST" means the process described on SCHEDULE 2.2.
                                                        ------------ 

     "CABS" means the Carrier Access Billing System which is contained in a 
document prepared under the direction of the Billing Committee of the OBF. The 
Carrier Access Billing System document is published by Bellcore in Volumes 1, 
1A, 2, 3, 3A, 4 and 5 as Special Reports SR-OPT-001868, SR-OPT-001869, 
SR-OPT-001871, SR-OPT-001872, SR-OPT-001873, SR-OPT-001874, and SR-OPT-001875,
respectively, contains the recommended guidelines for the billing of access and
other connectivity services.

     "CALLING PARTY NUMBER" or "CPN" is a Common Channel Interoffice Signaling 
("CCIS") parameter which refers to the number transmitted through a network 
identifying the calling party.

     "CARRIER OF RECORD" is as defined in SECTION 10.11.3.
                                          ---------------

     "CCS" means one hundred (100) call seconds.

                                 Sch. 1.2 - 2
<PAGE>
 
     "CENTRAL OFFICE SWITCH" means a switch used to provide Telecommunications
Services, including:

          (a)  "END OFFICE SWITCHES," which are used to terminate Customer
     station Loops for the purpose of Interconnection to each other and to
     trunks; and

          (b) "TANDEM OFFICE SWITCHES," OR "TANDEMS," which are used to connect
               and switch trunk circuits between and among other Central Office
               Switches.
               
     A Central Office Switch may also be employed as a combination End Office/
Tandem Office Switch.

     "CENTREX" means a Telecommunications Service associated with a specific
grouping of lines that uses Central Office switching equipment for call routing
to handle direct dialing of calls and to provide many private branch 
exchange-like features.

     "CLASS FEATURES" means certain CCIS-based features available to Customers
including: Automatic Call Back; Caller Identification and related blocking
features; Distinctive Ringing/Call Waiting; Selective Call Forward; and
Selective Call Rejection.

     "COMMERCIAL MOBILE RADIO SERVICE"' OR "CMRS" is As Defined in the Act.

     "COBO" is as defined in SECTION 12.12.2(b).
                             ------------------

     "COLLOCATION" is As Described in the Act.

     "COMBINATION" is as defined in SECTION 9.3.1.
                                    -------------

     "COMMISSION" or "MPSC" means the Michigan Public Services Commission.

     "COMMON CHANNEL INTEROFFICE SIGNALING" OR "CCIS" means the signaling
system, developed for use between switching systems with stored-program
control, in which all of the signaling information for one or more groups of
trunks is transmitted over a dedicated high-speed data link rather than on a
per-trunk basis and, unless otherwise agreed by the Parties, the CCIS used by
the Parties shall be SS7.

     "CONSEQUENTIAL DAMAGES" is as defined in SECTION 26.5.
                                              ------------

     "CONTRACT MONTH" means a calendar month (or portion thereof) during the
term of this Agreement. Contract Month 1 shall commence on the first day of
the first calendar month following the Effective Date and end on the last day of
that calendar month.

     "CONTRACT YEAR" means a twelve (12)-month period during the term of this
Agreement commencing on the Effective Date and each anniversary thereof

                              Sch. 1. 2 - 3
<PAGE>
 
     "CONTROL OFFICE" means the Central Office providing Tandem Switching
Capability for E9-1-1 calls. The Control Office controls switching of ANI 
information to the PSAP and also provides the Selective Routing feature,
standard speed calling features, call transfer capability and certain
maintenance functions for each PSAP.

      "CROSS CONNECTION" means a connection provided pursuant to Collocation at
the Digital Signal Cross Connect, Main Distribution Frame or other suitable
frame or panel between (i) the collocated Party's equipment and (ii) the
equipment of a third-party collocated Telecommunications Carrier or the
equipment or facilities of the other Party which provides such Collocation.

     "CUSTOMER" means a third-party residence or business that subscribes to
Telecommunications Services provided at retail by either of the Parties.

     "CUSTOMER LISTING(S)" means a list containing the names, the telephone
numbers, addresses and zip codes of Customers within a defined geographical
area, except to the extent such Customers have requested not to be listed in a
directory.

     "CUSTOMER NAME AND ADDRESS INFORMATION" or "CNA" means the name, service
address and telephone numbers of a Party's Customers for a particular Exchange
Area. CNA includes nonpublished listings, coin telephone information and
published listings.

     "CUSTOMER PROPRIETARY NETWORK INFORMATION" is As Defined in the Act.

     "CUSTOMER USAGE DATA" is as defined in SECTION 10.16.1.
                                            ---------------

     "DATA MANAGEMENT SYSTEM" or "DMS" means a system of manual procedures
and computer processes used to create, store and update the data required to
provide the Selective Routing ("SR") and ALI features.

     "DELAYING EVENT" means (a) any failure of a Party to perform any of its
obligations set forth in this Agreement, caused in whole or in part by (i) the
failure of the other Party to perform any of its obligations set forth in this
Agreement (including the Implementation Schedule and the Implementation Plan),
or (ii) any delay, act or failure to act by the other Party or its Customer,
agent or subcontractor or (b) any Force Majeure Event.

     "DELIVERY DATE" is as defined in SECTIONS 12.12.2(b) and 12.12.3(b).
                                      -------------------     ----------

     "DERIVATIVE INFORMATION" is as defined in SECTION 20.1.1(b).
                                               -----------------

     "DIALING PARTY" is As Defined in the Act.
           
     "DIGITAL SIGNAL LEVEL" means one of several transmission rates in the time-
division multiplex hierarchy.

                                 Sch. 1.2 - 4
<PAGE>
 
     "DIGITAL SIGNAL LEVEL 0" OR "DS0" means the 64 Kbps zero-level signal in
the time-division multiplex hierarchy.

     "DIGITAL SIGNAL LEVEL 1" OR "DS1" means the 1.544 Mbps first-level signal
in the time-division multiplex hierarchy. In the time-division multiplexing
hierarchy of the telephone network, DS1 is the initial level of multiplexing.

     "DIGITAL SIGNAL LEVEL 3" OR "DS3" means the 44.736 Mbps third-level in the
time-division multiplex hierarchy. In the time-division multiplexing hierarchy
of the telephone network, DS3 defined as the third level of multiplexing.

     "DISCLOSING PARTY" is as defined in SECTION 20.1.1.
                                         --------------

     "DISPUTE" is as defined in SECTION 28.3.
                                ------------

     "DISPUTED AMOUNTS" is as defined in SECTION 28.2.1.
                                         --------------

     "DOCUMENTATION OF AUTHORIZATION" is as defined in SCHEDULE 10.11.1.
                                                       ----------------

     "EFFECTIVE DATE" is the date indicated in the Preamble on wh1ch this
Agreement shall become effective.

     "EMERGENCY SERVICES" mean police, fire, ambulance, rescue and medical
services.

     "E9-1-1" or "ENHANCED 9-1-1 (E9-1-1) SERVICE" provides completion of 9-1-
1 calls via dedicated trunking facilities and includes Automatic Number
Identification (ANI), Automatic Location Identification (ALI) and/or Selective
Routing (SR).

     "EQUAL IN QUALITY" is as defined in SECTION 3.6.
                                         -----------

     "EXCHANGE ACCESS" is As Defined in the Act.

     "EXCHANGE AREA" means an area, defined by the Commission, for which a
distinct local rate schedule is in effect.

     "EXCHANGE MESSAGE RECORD" or "EMR" means the standard used for exchange
of Telecommunications message information among Telecommunications providers for
billable, non-billable, sample, settlement and study data. EMR format is
contained in Bellcore Practice BR-010-200-010 CRIS Exchange Message Record.

     "FCC" means the Federal Communications Commission.

     "FIBER-MEET" means an Interconnection architecture method whereby the
Parties physically Interconnect their networks via an optical fiber interface
(as opposed to an electrical interface) at

                                 Sch. 1.2 - 5
<PAGE>
 
a mutually agreed upon location, at which one Party's responsibility or
service begins and the other Party's responsibility ends.

     "FORCE MAJEURE EVENT" is as defined in SECTION 30.5.
                                            ------------

     "FORECAST PROVIDER" is as defined in SECTION 19.5.3.
                                          --------------

     "GRANDFATHERED SERVICES" is as defined in SECTION 10.3.1.
                                               --------------

     "HAZARDOUS SUBSTANCES" is as defined in SECTION 19.4.
                                             ------------

     "HDSL" or "HIGH-BIT RATE DIGITAL SUBSCRIBER LINE" means a transmission
technology which transmits up to a DS1-level signal, using any one of the
following line codes: 2 Binary/ 1 Quartenary ("2BIQ"), Carrierless AM/PM,
Discreet Multitone ("DMT"), or 3 Binary / 1 Octel ("3B10").

     "IMPLEMENTATION PLAN" is as defined in SECTION 18.2.
                                            ------------

     "IMPLEMENTATION TEAM" is as defined in SECTION 18.1.
                                            ------------

     "INCUMBENT LOCAL EXCHANGE CARRIER" OR "ILEC" is As Defined in the Act.

     "INFORMATION SERVICE TRAFFIC" means Local Traffic or IntraLATA Toll
Traffic which originates on a Telephone Exchange Service line and which
is addressed to an information service provided over a Party's information
services platform (e.g., 976).

     "INITIAL BILLING COMPANY" OR "IBC" means the Local Exchange Carrier which
provides the Feature Group B or D services in an End Office. For purposes of
this Agreement, Focal is the IBC.

     "INITIAL TERM" is as defined in SECTION 21.1.
                                     ------------

     "INSUFFICIENT CAPACITY" is as defined in SECTION 16.1.2.
                                              --------------

     "INTEGRATED DIGITAL LOOP CARRIER" means a subscriber loop carrier system
that is twenty-four (24) local Loop transmission paths combined into a 1.544
Mbps digital signal which integrates within the switch at a DS1 level.

     "INTEGRATED SERVICES DIGITAL NETWORK" OR "ISDN" means a switched network
service that provides end-to-end digital connectivity for the simultaneous
transmission of voice and data. Basic Rate Interface-ISDN (BRI-ISDN) provides
for a digital transmission of two 64 Kbps bearer channels and one 16 Kbps data
channel (2B+D).

     "INTELLECTUAL PROPERTY" means copyrights, patents, trademarks, trade-
secrets, mask works and all other intellectual property rights.
                                                      
                                 Sch. 1.2 - 6
<PAGE>
 
     "INTERCONNECTION" is As Defined in the Act.

     "INTERCONNECTION ACTIVATION DATE" is as defined in SECTION 2.1.
                                                        -----------

     "INTEREXCHANGE CARRIER" or "IXC" means a carrier that provides interLATA or
intraLATA Telephone Toll Services.

     "INTERIM TELECOMMUNICATIONS NUMBER PORTABILITY" OR "INP" is as described
in the Act.

     "INTERLATA" is As Defined in the Act.

     "INTRALATA TOLL TRAFFIC" means all intraLATA calls other than Local Traffic
calls but including interzone calls.

     "LISTING UPDATE(S)" means information with respect to Customers necessary
for Publisher to publish directories under this Agreement in a form and format
acceptable to Publisher. For Customers whose telephone service has changed since
the last furnished Listing Update because of new installation, disconnection,
change in address, change in name, change in non-listed or non-published status,
or other change may affect the listing of the Customer in a directory, Listing
Updates shall also include information necessary in order for Publisher to
undertake initial delivery and subsequent delivery of directories, including
mailing addresses, delivery addresses and quantities of directories requested by
a Customer. In the case of Customers who have transferred service from another
LEC to Focal without change of address, Listing Updates shall also include the
Customer's former listed telephone number and former LEC, if available.
Similarly, in the case of Customers who have transferred service from Focal to
another LEC, Listing Updates shall also include the Customer's referral
telephone number and new LEC, if available.

     "LINE INFORMATION DATABASE(S) (LIDB)" means one or all, as the context may
require, of the Line Information Databases owned individually by ILECs and other
entities which provide, among other things, calling card validation
functionality for telephone line number cards issued by ILECs and other
entities. A LIDB also contains validation data for collect and third number-
billed calls, which include billed number screening.

     "LOCAL ACCESS AND TRANSPORT AREA" or "LATA" is As Defined in the Act.

     "LOCAL EXCHANGE CARRIER" or "LEC" is As Defined in the Act.

     "LOCAL LOOP TRANSMISSION" or "LOOP" means the transmission path which
extends from Network Interface Device or demarcation point at a Customer's
premises to the Main Distribution Frame or other designated frame or panel in
a Party's Wire Center which services the Customer. Loops are defined by the
electrical interface rather than the type of facility used.

                                 Sch. 1.2 - 7
<PAGE>
 
     "LOCAL NUMBER PORTABILITY" OR "LNP" means the ability of users of
Telecommunications Services to retain, at the same location, existing telephone
numbers without impairment of quality, reliability, or convenience when
switching from one Telecommunications Carrier to another.

     "LOCAL TRAFFIC" means those calls as defined by Ameritech's local calling
area as described in maps, tariffs, or rule schedules filed with and approved by
the Commission as of the Effective Date.

     "LOSS" or "LOSSES" means any and all losses, costs (including court
costs), claims, damages (including fines, penalties, and  criminal or civil
judgments and settlements), injuries, liabilities and expenses (including
attorneys' fees).

     "MAIN DISTRIBUTION FRAME" means the distribution frame of the Party
providing the Loop used to interconnect cable pairs and line and trunk equipment
terminals on a switching system.

     "MAKE-READY WORK" means all work, including rearrangement or transfer
of existing facilities or other changes required to accommodate Focal's
Attachments.

     "MECAB" refers to the Multiple Exchange Carrier Access Billing (MECAB)
document prepared by the Billing Committee of the Ordering and Billing Forum
(OBF), which functions under the auspices of the Carrier Liaison Committee
(CLC) of the Alliance for Telecommunications Industry Solutions (ATIS). The
MECAB document published by Bellcore as Special Report SR-BDS-000983 contains
the recommended guidelines for the billing of an access service provided by
two or more LECs, or by one LEC in two or more states within a single LATA.

     "MEET-POINT BILLING" means the process whereby each Party bills the
appropriate tariffed rate for its portion of a jointly provided Switched
Exchange Access Service.

     "MULTIPLE BILL/SINGLE TARIFF" means that each Party will prepare and
render its own meet point bill in accordance with its own tariff for its portion
of the switched access service.

     "NETWORK ELEMENT" is As Defined in the Act.

     "NORTH AMERICAN NUMBERING PLAN" or "NANP" means the numbering plan used in
the United States that also serves Canada, Bermuda, Puerto Pico and certain
Caribbean Islands. The NANP format is a 10-digit number that consists of a 3-
digit NPA code (commonly referred to as the area code), followed by a 3-digit
NXX code and 4-digit line number.

     "NUMBER PORTABILITY" is As Defined in the Act.

     "NXX" means the three-digit code which appears as the first three digits
of a seven-digit telephone number.

                                 Sch. 1.2 - 8
<PAGE>
 
      "OBF" means the Ordering and Billing Forum (OBF), which functions under
the auspices of the Carrier Liaison Committee (CLC) of the Alliance for
Telecommunications Industry Solutions (ATIS).

     "OCCUPANCY DATE" is as defined in SECTION 12.12.2(E).
                                       ------------------

     "OPTICAL LINE TERMINATING MULTIPLEXOR" or "OLTM" is as defined in
SECTION 3.3.
-----------

     "PARTY" means either Ameritech or Focal, and "PARTIES" means Ameritech and
Focal.

     "PHYSICAL COLLOCATION" is As Defined in the Act.

     "PIC" is as defined in SECTION 10.11.4.
                            ---------------

     "PLAN" is as defined in SECTION 8.1.
                             -----------

     "PREMISES" is As Defined in the Act.

     "PRIMARY LISTING" means the single directory listing provided to Customers
by Publisher under the terms of this Agreement. Each telephone configuration
that allows a terminating call to hunt for an available time among a series of
lines shall be considered a single Customer entitled to a single primary
listing.

     "PROPRIETARY INFORMATION" is as defined in SECTION 20.1.1.
                                                 --------------

     "PUBLIC SAFETY ANSWERING POINT" or "PSAP" means an answering location for
9-1-1 calls originating in a given area. A PSAP may be designed as Primary or
Secondary, which refers to the order in which calls are directed for answering.
Primary PSAPs respond first; Secondary PSAPs receive calls on a transfer basis
only, and generally serve as a centralized answering location for a particular
type of emergency call. PSAPs are staffed by employees of Service Agencies such
as police, fire or emergency medical agencies or by employees of a common bureau
serving a group of such entities.

     "PUBLISHER" means Ameritech's White Pages Directories publisher.

     "RATE CENTER" means the specific geographic point which has been designated
by a given LEC as being associated with a particular NPA-NXX code which has been
assigned to the LEC for its provision of Telephone Exchange Service. The Rate
Center is the finite geographic point identified by a specific V&H coordinate,
which is used by that LEC to measure, for billing purposes, distance sensitive
transmission services associated with the specific Rate Center; provided that a
                                                                --------
Rate Center cannot exceed the boundaries of an Exchange Area as defined by the
Commission.

     "RECEIVING PARTY" is as defined in SECTION 20.1.1.
                                        --------------

                                 Sch. 1.2 - 9
<PAGE>
 
      "RECIPROCAL COMPENSATION" is As Described in the Act.

      "REFERRAL ANNOUNCEMENT" is as defined in ARTICLE XVII.
                                               ------------

      "RENEWAL TERM" is as defined in SECTION 21.1
                                      ------------

      "RESALE LISTING(S)" means a list containing the names, the telephone
numbers, addresses and zip codes of Customers of Focal within the defined
geographic area, except to the extent such Customers of Focal have requested
not to be listed in a directory.

      "RESALE SERVICES" is as defined in SECTION 10.1.
                                         ------------

      "RESALE TARIFF" is as defined in SECTION 10.11.2.
                                       ---------------

      "ROUTING POINT" means a location which a LEC has designated on its own
network as the homing (routing) point for inbound traffic to one or more of its
NPA-NXX codes. The Routing Point is also used to calculate mileage measurements
for the distance-sensitive transport element charges of Switched Exchange Access
Services. Pursuant to Bellcore Practice BR 795-100-100 (the "RP PRACTICE"), the
Routing Point (referred to as the "RATING POINT" in such RP Practice) may be an
End Office Switch location, or a "LEC CONSORTIUM POINT OF INTERCONNECTION".
Pursuant to such RP Practice, each "LEC CONSORTIUM POINT OF INTERCONNECTION"
shall be designated by a common language location identifier (CLLI) code with
(x)KD in positions 9, 10, 11, where (x) may be any alphanumeric A-Z or 0-9. The
Routing Point must be located within the LATA in which the corresponding NPA-NXX
is located. However, Routing Points associated with each NPA-NXX need not be the
same as the corresponding Rate Center, nor must there be a unique and separate
Routing Point corresponding to each unique and separate Rate Center; provided
                                                                     --------
only that the Routing Point associated with a given NPA-NXX must be located in
the same LATA as the Rate Center associated with the NPA-NXX.

      "SELECTIVE ROUTING" OR "SR" means an E9-1-1 feature that routes an E9-1-1
call from a Control Office to the designated Primary PSAP based upon the
identified number of the calling party.

      "SERVICE AGENCY" means the public agency, the State or any local
government unit or special purpose district which has the authority to provide
police, fire fighting, medical or other emergency services, which has requested
the local telephone company to provide an E9-1-1 Telecommunications Service for
the purpose of voice-reporting emergencies by the public.

      "SERVICE CONTROL POINT" OR "SCP" is As Defined in the Act.

      "SERVICE LINE" means a telecommunications link from the Central Office
terminating at the PSAP.

                                 Sch. 1.2 - 10
<PAGE>
 
      "SIGNALING END POINT" OR "SEP" means a signaling point, other than an STP,
which serves as a source or a repository for CCIS messages.

      "SIGNAL TRANSFER POINT" OR "STP" is As Defined in the Act.

      "SUBSEQUENT BILLING COMPANY" OR "SBC" means the Local Exchange Carrier
which provides a segment of transport or switching services in connection with
Feature Group B or D switched access service. For purposes of this Agreement,
Ameritech is initially the SBC.

      "SUNSETTED SERVICES" is as defined in SECTION 10.3.2.
                                            --------------

      "SWITCHED ACCESS DETAIL USAGE DATA" means a category 1101XX record as
defined in the EMR Bellcore Practice BR 010-200-010.

      "SWITCHED ACCESS SUMMARY USAGE DATA" means a category 1150XX record as
defined in the EMR Bellcore Practice BR 010-200-010.

      "SWITCHED EXCHANGE ACCESS SERVICE" means the offering of transmission or
switching services to Telecommunications Carriers for the purpose of the
origination or termination of Telephone Toll Service. Switched Exchange Access
Services include: Feature Group A, Feature Group B, Feature Group D, 800/888
access, and 900 access and their successors or similar Switched Exchange Access
Services.

      "SYNCHRONOUS OPTICAL NETWORK" or "SONET" means an optical interface
standard that allows inter-networking of transmission products from multiple
vendors. The base rate is 51.84 Mbps (OC-1/STS-1) and higher rates are direct
multiples of the base rate, up to 13.22 Gpbs.

      "TECHNICAL REFERENCE SCHEDULE" is the list of technical references set
forth in SCHEDULE 2.3.
         ------------

      "TECHNICALLY FEASIBLE POINT" is As Described in the Act.

      "TELECOMMUNICATIONS" is As Defined in the Act.

      "TELECOMMUNICATIONS ACT" means the Telecommunications Act of 1996 and any
rules and regulations promulgated thereunder.
 
      "TELECOMMUNICATIONS ASSISTANCE PROGRAM" means any means-tested or
subsidized Telecommunications Service offering, including Lifeline, that is
offered only to a specific category of subscribers.

      "TELECOMMUNICATIONS CARRIER" is As Defined in the Act.

      "TELECOMMUNICATIONS SERVICE" is As Defined in the Act.

                                 Sch. 1.2 - 11
<PAGE>
 
     "TELEPHONE EXCHANGE SERVICE" is As Defined in the Act.

     "TELEPHONE RELAY SERVICE" means a service provided to speech and hearing-
impaired callers that enables such callers to type a message into a telephone
set equipped with a keypad and message screen and to have a live operator read
the message to a recipient and to type message recipient's response to the
speech or hearing-impaired caller.

      "TELEPHONE TOLL SERVICE" is As Defined in the Act.

      "FOCAL DIRECTORY CUSTOMER" is as defined in SECTION 15.1.
                                                  ------------

      "UNAUTHORIZED SWITCHING" is as defined in SECTION 10.11.2(a).
                                                ------------------

      "VIRTUAL COLLOCATION" is As Defined in the Act.

      "WHITE PAGES DIRECTORIES" means directories or the portion of co-bound
directories which include a list in alphabetical order by name of the telephone
numbers and addresses of telecommunication company customers.

     "WHOLESALE RESALE SERVICES" is as defined in SECTION 10.1.
                                                  ------------

     "WIRE CENTER" means the Premises of a Party which serves as a Routing Point
for Switched Exchange Access Service.

                                 Sch. 1.2 - 12
                                         
<PAGE>
 
                                  SCHEDULE 2.1
                           IMPLEMENTATION SCHEDULE
                                   Michigan

                                
<TABLE> 
<CAPTION>                      
  LATA    LEC Office CLLI        Focal             Ameritech     Interconnection
                             Interconnection    Interconnection  Activation Date
                              Wire Center         Wire Center  
                                 FIWC               (AIWC)      
<S>     <C>                <C>                 <C>              <C>
        Tandems

340     DTRTMIBH20T        DTRTMIMDH02         SFLDMIMKDSO      See Note 1

340     PNTCMIM50T         PNTCMIMNH15         SFLDMIMKDSO      "

340     WAYNMIMN20T        WAYNMIMMNH00        SFLDMIMKDSO      "

340     WBFDMIMN20T        SFLDMIMNH13         SFLDMIMKDSO      "           
 

        End Offices

340     ABHGMIMNDSO        ABHGMIMNHOO         SFLDMIMKDSO      See Note 1

340     ANARMIMNDSO        WAYNMIMNHOO         SFLDMIMKDSO      "

340     BITNMIESDSO        NRVLMIMNHOO         SFLDMIMKDSO      "

340     BRHMMIMNDSO        BRHMMIMNHOO         SFLDMIMKDSO      "           

340     CKTNMIMNDSO        PNTCMIMNH15         SFLDMIMKDSO      "

340     CMRCMIMNDSO        PNTCMIMNH15         SFLDMIMKDSO      "

340     CNLNMIMNDSO        CNLNMIMNHOI         SFLDMIMKDSO      "

340     DTRTMIVWDSO        DTRTMIBLH23         SFLDMIMKDSO      "

340     DRBRMIDBDSO        DRBRMIFBHO7         SFLDMIMKDSO      "

340     DRBRMIFBDSO        DRBRMIFBH07         SFLDMIMKDSO      "

340     DRBRMIFBDSI        DRBRMIFBH07         SFLDMIMKDSO      "

340     DRBRMIORDSO        DRBRMIFBH07         SFLDMIMKDSO      "

340     DRPLMIDPDSO        PNTCMIMNH15         SFLDMIMKDSO      "

340     FLNTMIMNDSO        PNTCMIMNH15         SFLDMIMKDSO      "

340     FLRKMIFRDSO        DRBRMIFBH07         SFLDMIMKDSO      "

340     HGPKMITSDSO        DTRTMIMDH02         SFLDMIMKDSO      "

340     HOWLMIMNDSO        NRVLMIMNH00         SFLDMIMKDSO      "
</TABLE>                                       
                                               
                                 Sch. 2.1 - 1
<PAGE>
 
<TABLE> 
<CAPTION>                      
  LATA    LEC Office CLLI        Focal             Ameritech     Interconnection
                             Interconnection    Interconnection  Activation Date
                              Wire Center         Wire Center  
                                 FIWC               (AIWC)      
<S>     <C>                <C>              <C>                 <C>
340     LIVNMIMNDSO        LIVNMIMNH01      SFLDMIMKDSO         " 

340     LNPKMIATDSO        DRBRMIFBHO7      SFLDMIMKDSO         " 

340     MTCLMICLDSO        TROYMISMH06      SFLDMIMKDSO         " 

340     MTCLMIMNDSO        TROYMIMNH06      SFLDMIMKDSO         " 

340     MTCLMINRDSO        TROYMIMNH06      SFLDMIMKDSO         " 

340     PLMOMIMNDSO        PLMOMIMNH00      SFLDMIMKDSO         " 

340     PTHRMIMNDSO        PNTCMIMNH15      SFLDMIMKDSO         " 

340     RMLSMIMNDSO        WAYNMIMNH00      SFLDMIMKDSO         " 

340     ROCHMIMNDSO        PNTCMIMNH15      SFLDMIMKDSO         " 

340     RSVLMIMNDSO        CNLNMIMNH01      SFLDMIMKDSO         " 

340     RYLOMIMNDSO        RYLOMIMNH02      SFLDMIMKDSO         " 

340     SFLDMIMNDSO        SFLDMIMNH13      SFLDMIMKDSO         " 

340     SFLDMIMNDS1        SFLDMIMNH13      SFLDMIMKDSO         " 

340     SFLDMIOKDSO        SFLDMIMNH13      SFLDMIMKDSO         " 

340     TAYLMIWKDSO        DRBPMIFBH07      SFLDMIMKDSO         " 

340     TRENMIMNDSO        DRBRMIFBH07      SFLDMIMKDSO         " 

340     TROYMIMNDSO        TROYMIMNH06      SFLDMIMKDSO         " 

340     TROYMISMDSO        TROYMISMH06      SFLDMIMKDSO         " 

340     UTICMIMNDSO        ABHGMIMNH00      SFLDMIMKDSO         " 

340     WBFDMIMNDSO        SFLDMIMNH13      SFLDMIMKDSO         " 

340     WKLKMIMNDSO        NRVLMIMNH00      SFLDMIMKDSO         " 

340     WRRNMIMNDSO        WRRNMIMNH01      SFLDMIMKDSO         " 

340     WRRNMITLDSO        WRRNMITLH00      SFLDMIMKDSO         " 

340     YPSLMIMNDSO        WAYNMIMNH00      SFLDMIMKDSO         " 
</TABLE> 

Note I - Interconnection Activation Date is 150 days from the execution date on
the signature block.

                                 Sch. 2.1 - 2
<PAGE>
 
                                  SCHEDULE 2.2

                               BONA FIDE REQUEST

      1.  Ameritech shall promptly consider and analyze the submission of a
Bona Fide Request that Ameritech provide: (a) Interconnection, access to an
unbundled Network Element (including Combinations thereof) not otherwise
provided hereunder at the time of such request; (b) an Interconnection or
connection to a Network Element that is different in quality to that which
Ameritech provides itself at the time of such request; or (c) a customized
service for features, capabilities, functionalities or unbundled Network Element
not otherwise provided hereunder at the time of such request.

      2.  A Bona Fide Request shall be submitted in writing and shall include a
technical description of each requested Interconnection, Network Element,
Combination and/or customized feature, capability or functionality.

      3.  Focal may cancel a Bona Fide Request at any time, but shall pay
Ameritech's reasonable and demonstrable costs of processing and/or implementing 
the Bona Fide Request up to the date of cancellation, except if (i) any 
processing charges are of the type which are not generally passed on by 
Ameritech to its retail or resale Customers and (ii) such costs or cost 
categories representing such charges are not included in the prices Focal pays 
for the services provided by Ameritech under this Agreement.

      4.  Within five (5) Business Days of its receipt, Ameritech shall
acknowledge receipt of the Bona Fide Request.

      5.  Within thirty (30) days of its receipt of a Bona Fide Request,
Ameritech shall provide to Focal a preliminary, analysis of such
Interconnection, Network Element, or requested level of quality thereof that is
the subject of the Bona Fide Request or customized feature, capability or
functionality. The preliminary analysis shall confirm that Ameritech will either
offer access to the Interconnection, Network Element, or requested level of
quality or will provide a detailed explanation that access to such
Interconnection, Network Element, or requested level of quality is not
technically feasible and/or that the request does not qualify as an
Interconnection, Network Element, or requested level of quality that is required
to be provided under the Act. If the receiving Party determines that the
Interconnection, Network Element, or requested level of quality that is the
subject of the Bona Fide Request is technically feasible and is otherwise
required to be provided under the Act, Ameritech shall provide Focal a firm
price proposed and availability date for such development ("BONA FIDE REQUEST
QUOTE"). For Bona Fide Requests that involve either: (i) combinations of
standard offerings or (ii) individual customer arrangements that do not require
alterations not otherwise performed for individual customer arrangements, for
Ameritech retail customers, Ameritech shall provide a Bona Fide Request Quote
within such thirty (30)-day period. For all other Bona Fide Requests, Ameritech
shall provide a Bona Fide Request Quote as soon as feasible, but in any event
not more than sixty (60) days from the date Ameritech received such Bona Fide
Request. 

      6.  Within thirty (30) days of  receipt of the Bona Fide Request Quote, 
the requesting Party must either confirm its order for such Interconnection or 
Network Element pursuant to the Bona Fide Request Quote or, if it believes such 
quote is inconsistent with the requirements of the Act, exercise its rights 
under SECTION 28.3.
      ------------

      7.  Unless Focal agrees otherwise, all prices shall be consistent with
 the pricing principles of the Act, FCC and/or the Commission.

      8.  If a Party to a Bona Fide Request believes that the other Party
is not requesting, negotiating,or processing the Bona Fide Request in good
faith, or disputes a determination, or price or cost quote, such Party may
exercise its rights under SECTION 28.3.
                          ------------

                                 Sch. 2.2 - 1
<PAGE>
 
                                 SCHEDULE 2.3

                         TECHNICAL REFERENCE SCHEDULE

 Unbundled Network Elements
 --------------------------

      Unbundled Loop Transmission
      ---------------------------

      Bellcore TA-NWT-000393
      ANSI T1.413-1995 Specifications
      AM TR-TMO-000122
      AM TR-TMO-000123
      Bellcore TR-NWT-000393
      ANSI T1. 102-1993, American National Standard for Telecommunication -
          Digital Hierarchy - Electrical Interfaces
      Bellcore Technical Requirement TR-NWT-000499, Issue 5, December 1993,
          section 7
      ANSI T1.413-1995
      ANSI TIE 1 Committee Technical report Number 28

      Local Switching
      ---------------

      Bellcore FR-NWT-000064 (Local Switching Systems General Requirements)
      Bellcore GR-1432-CORE (TCAP)
      Bellcore GR-905-CORE (ISUP)
      Bellcore GR-1429-CORE (Call Management)
      Bellcore GR-1357-CORE (Switched Fractional DS1)
      Bellcore GR-1428-CORE (Toll Free Service)
      Bellcore GR-1597-CORE (Calling Name)
      Bellcore GR-954-CORE (Line Information Database)
      Bellcore GR-2863-CORE (Advanced Intelligent Network)
      GR-1298-CORE, AIN Switching System Generic Requirements
      GR-1299-CORE, AIN Switch-Service Control Point (SCP)/Adjunct Interface
          Generic Requirements
      TR-NWT-001284, AIN 0.1 Switching System Generic Requirements
      SR-NWT-002247, AIN Release 1 Update
      ANSI standards Q.931, Q.932
      Bellcore TR-NWT-08
      Bellcore TR-NWT-303
      TR-NWT-000393, January 1991, Generic Requirements for ISDN Basic Access
          Digital Subscriber Lines
      Bellcore TR-NWT-303

                                 Sch. 2.3 - 1
<PAGE>
 
      Dedicated and Shared Transport
      ------------------------------

      AM TR-NIS-000111
      AM RT-NIS 000133
      ANSI T1.101-1994, American National Standard for Telecommunications -
           Synchronization Interface Standard Performance and Availability
      ANSI T1.102-1993 American National Standard for Telecommunications -
          Digital Hierarchy - Electrical Interfaces
      ANSI T1.105-1995, American National Standard for Telecommunications -
           Synchronous Optical Network (SONET) - Basic Description including
           Multiplex Structure, Rates and Formats
      ANSI T1.105.01-1995, American National Standard for Telecommunications -
           Synchronous Optical Network (SONET) - Automatic Protection Switching
      ANSI T1.105.02-1995, American National Standard for Telecommunications
           - Synchronous Optical Network (SONET) - Payload Mappings
      ANSI T1.105.03-1994, American National Standard for Telecommunications -
           Synchronous Optical Network (SONET) - Jitter at Network Interfaces
      ANSI T1.105.03a-1995, American National Standard for Telecommunications
           - Synchronous Optical Network (SONET)- Jitter at Network Interfaces
           - DS1 Supplement
      ANSI T1.105.04-1995, American National Standard for Telecommunications -
           Synchronous Optical Network (SONET) - Data Communication Channel
           Protocols and Architectures
      ANSI T1.105.05-1994, American National Standard for Telecommunications -
           Synchronous Optical Network (SONET) - Tandem Connection
      ANSI T1.106-1988, American National Standard for Telecommunications -
           Digital Hierarchy - Optical Interface Specifications (Single Mode)
      ANSI T 1.107-1988, American National Standard for Telecommunications -
           Digital Hierarchy - Formats Specifications
      ANSI T 1.107a-1990, American National Standard for Telecommunications -
           Digital Hierarchy - Supplement to Formats Specifications (DS3 Format
           Applications)
      ANSI T1.107b-1991, American National Standard for Telecommunications
           Digital Hierarchy - Supplement to Formats Specifications
      ANSI T1.117-1991, American National Standard for Telecommunications
           Digital Hierarchy - Optical Interface Specifications (SONET) (Single
           Mode - Short Reach)
      ANSI T1.119-1994, American National Standard for Telecommunications -
           Synchronous Optical Network (SONET) - Operations, Administration,
           Maintenance, and Provisioning (OAM&P) Communications
      ANSI T1.119.01-1995, American National Standard for Telecommunications -
           Synchronous Optical Network (SONET) - Operations, Administration,
           Maintenance, and Provisioning (OAM&P) Communications Protection
           Switching Fragment 
      ANSI T1.119.02-199x, American National Standard for Telecommunications -
           Synchronous Optical Network (SONET) - Operations, Administration,
           Maintenance, and Provisioning (OAM&P) Communications Performance
           Monitoring Fragment

                                 Sch. 2.3 - 2
<PAGE>
 
      ANSI T1.231-1993, American National Standard for Telecommunications -
           Digital Hierarchy - Layer 1 In-Service Digital Transmission
           performance monitoring
      ANSI T1.403-1989, Carrier to Customer Installation, DS1 Metallic Interface
           Specification
      ANSI T1.404-1994, Network-to-Customer Installation - DS3 Metallic
           Interface Specification
      Bellcore FR-440 and TR-NWT-000499, Transport Systems Generic Requirements
           (TSGR): Common Requirements
      Bellcore GR-820-CORE, Generic Transmission Surveillance: DS1 & DS3
           Performance
      Bellcore GR-253-CORE, Synchronous Optical Network Systems (SONET); Common
           Generic Criteria
      Bellcore TR-NWT 000507, Transmission, Section 7, Issue 5 (Bellcore,
           December 1993). (A module of LSSGR, FR-NWT-000064.)
      Bellcore TR-NWT-000776, Network Interface Description for ISDN Customer
           Access
      Bellcore TR-INS-000342, High-Capacity Digital Special Access Service-
           Transmission Parameter Limits and Interface Combinations, Issue 1,
           February 1991

      Signaling Transfer Points (STPs)
      --------------------------------

      ANSI T1.111.2 
      ANSI T1.111.3
      ANSI T1.111.4
      ANSI T1.112
      ANSI T1.112.4
      ANSI T1.118
      ANSI T1.111.6
      ANSI T1.112.5
      GR-2863-CORE, CCS Network Interface Specification Supporting Advanced
           Intelligent Network (AIN)
      GR-2902-CORE, CCS Network Interface Specification (CCSNIS) Supporting
           Toll-Free Service Using Advanced Intelligent Network (AIN)
      Bellcore GR-905-CORE, Common Channel Signaling Network Interface
           Specification (CCSNIS) Supporting Network Interconnection, Message
           Transfer Part (MTP), and Integrated Services Digital Network User
           Part (ISDNUP)
      Bellcore GR-1432-CORE, CCS Network Interface Specification (CCSNIS)
           Supporting Signaling Connection Control Part (SCCP) and Transaction
           Capabilities Application Part (TCAP)
      ANSI T1.111-1992, American National Standard for Telecommunications -
           Signaling System Number 7 (SS7) - Message Transfer Part (MTP)
      ANSI T1.111A-1994, American National Standard for Telecommunications -
           Signaling System Number 7 (SS7) - Message Transfer Part (MTP) 
           Supplement
      ANSI T1.112-1992, American National Standard for Telecommunications -
           Signaling System Number 7 (SS7) - Signaling Connection Control Part
           (SCCP)
      ANSI T1.115-1990, American National Standard for Telecommunications -
           Signaling System Number 7 (SS7) - Monitoring and Measurements for 
           Networks

                                 Sch. 2.3 - 3
<PAGE>
 
      ANSI T1.116-1990, American National Standard for Telecommunications -
           Signaling System Number 7 (SS7) - Operations, Maintenance and
           Administration Part (OMAP)
      ANSI T1.118-1992, American National Standard for Telecommunications -
           Signaling System Number 7 (SS7) - Intermediate Signaling Network
           Identification (ISNI)
      Bellcore GR-905-CORE, Common Channel Signaling Network Interface
           Specification (CCSNIS) Supporting Network Interconnection, Message
           Transfer Part (MTP), and Integrated Services Digital Network User
           Part (ISDNUP)
      Bellcore GR-1432-CORE, CCS Network Interface Specification (CCSNIS)
           Supporting Signaling Connection Control Part (SCCP) and Transaction
           Capabilities Application Part (TCAP)

      Service Control Points (SCPs)/Call-Related Databases
      ----------------------------------------------------

      SR-TSV-002275 (BOC Notes on the Ameritech Networks, SR-TSV-002275, Issue
           2 (Bellcore, April 1994))
      GR-246-CORE, Bell Communications Research Specification of Signaling
           System Number 7, ISSUE 1 (Bellcore, December 1995)
      GR-1432-CORE, CCS Network Interface Specification (CCSNIS) Supporting
           Signaling Connection Control Part (SCCP) and Transaction 
           Capabilities Application Part (TCAP). (Bellcore, March 1994)
      GR-954-CORE, CCS Network Interface Specification (CCSNIS) Supporting
           Line Information Database (LIDB) Service 6, Issue 1, Rev. I
           (Bellcore, October 1995)
      GR-1149-CORE, OSSGR Section 10: System Interfaces, Issue 1 (Bellcore,
           October 1995) (Replaces TR-NWT-001149)
      GR-1158-CORE, OSSGR Section 22.3: Line Information Database 6, Issue
           (Bellcore, October 1995)
      GR-1428-CORE, CCS Network Interface Specification (CCSNIS) Supporting
           Toll Free Service (Bellcore, May 1995)
      BOC Notes on Ameritech Networks, SR-TSV-002275, ISSUE 2 (Bellcore, April
           1994)
      GR- 1280-CORE, AIN Service Control Point (SCP) Generic Requirements

      Tandem Switching
      ----------------

      Bellcore TR-TSY-000540, Issue 2R2, Tandem Supplement, 6/1/90
      GR-905-CORE
      GR-1429-CORE
      GR-2863-CORE
      GR-2902-CORE

      Performance Standards
      ---------------------

      Bellcore FR-64, LATA Switching Systems Generic Requirements (LSSGR)
  
                                 Sch. 2.3 - 4
<PAGE>
 
      Bellcore TR-NWT-000499, Issue 5, Rev 1, April 1992, Transport Systems
           Generic Requirements (TSGR): Common Requirements
      Bellcore TR-NWT-000418, Issue 2, December 1992, Generic Reliability
           Assurance Requirements For Fiber Optic Transport Systems
      Bellcore TR-NWT-000057, Issue 2, January 1993, Functional Criteria for
           Digital Loop Carriers Systems
      Bellcore TR-NWT-000507, Issue 5, December 1993, LSSGR - Transmission,
           Section 7
      Bellcore TR-TSY-000511, Issue 2, July 1987, Service Standards, a Module
           (Section 11) of LATA Switching Systems Generic Requirements (LSSGR,
           FR-NWT-000064)
      BELLCORE TR-NWT-000393, January 1991, Generic Requirements for ISDN
           Basic Access Digital Subscriber Lines
      Bellcore TR-NWT-000909, December 1991, Generic Requirements and
           Objectives for Fiber In The Loop Systems
      Bellcore TR-NWT-000505, Issue 3, May 1991, LSSGR Section 5, Call
           Processing
      Bellcore LSSGR TR-TSY-000511
      Bellcore TR-NWT-001244, Clocks for the Synchronized Network: Common
           Generic Criteria
      ANSI T1.105 -1995

      Network Interface Device
      ------------------------

      Bellcore Technical Advisory TA-TSY-000120, "Customer Premises or Network
           Ground Wire"
      Bellcore Generic Requirement GR-49-CORE, "Generic Requirements for Outdoor
           Telephone Network Interface Devices"
      Bellcore Technical Requirement TR-NWT-00239, "Indoor Telephone Network
           Interfaces"
      Bellcore Technical Requirement TR-NWT-000937, "Generic Requirements
           for Outdoor and Indoor Building Entrance"

Interconnection
---------------

     Trunking Interconnection
     -------------------------

     GR-317-CORE, Switching System generic requirements for Call Control
           Using the Integrated Services Digital Network User Part (ISDNUP),
           Bellcore, February, 1994

     GR-394-Core, Switching System generic requirements for Interexchange
           Carrier Interconnection Using the Integrated Services Digital Network
           User Part (ISDNUP), Bellcore, February, 1994

      FR-NWT-000064, LATA Switching Systems Generic Requirements (LSSGR),
           Bellcore, 1994 Edition
      ANSI T1. 111
      ANSI T1. 112
      ANSI T1. 113

                                 Sch. 2.3 - 5
<PAGE>
 
     Bellcore GR-905-CORE, Common Channel Signaling Network Interface
           Specification (CCSNIS) Supporting Network Interconnection, Message 
           Transfer Part (MTP), and Integrated Services Digital Network User 
           Part (ISDNUP)
     Bellcore GR-1428-CORE, CCS Network Interface Specification (CCSNIS)
           Supporting Toll-Free Service
     Bellcore GR-1429-CORE, CCS Network Interface Specification (CCSNIS)
           Supporting Call Management Services
     Bellcore GR-1432-CORE, CCS Network Interface Specification (CCSNIS)
           Supporting Signaling Connection Control Part (SCCP) and Transaction
           Capabilities Application Part (TCAP)
     ANSI T1.110-1992, American National Standard Telecommunications - 
           Signaling System Number 7 (SS7) - General Information;
     ANSI T1.111-1992, American National Standard for Telecommunications -
           Signaling System Number 7 (SS7) - Message Transfer Part (MTP)
     ANSI T1.111 A-1994, American National Standard for Telecommunications -
           Signaling System Number 7 (SS7) - Message Transfer Part (MTP)
           Supplement
     ANSI T1.112-1992, American National Standard for Telecommunications -
           Signaling System Number 7 (SS7) - Signaling Connection Control Part
           (SCCP)
     ANSI T1.113-1995, American National Standard for Telecommunications -
           Signaling System Number 7 (SS7) - Integrated Services Digital Network
           (ISDN) User Part 
     ANSI T1.114-1992, American National Standard for Telecommunications -
           Signaling System Number 7 (SS7) - Transaction Capabilities
           Application Part (TCAP)
     ANSI T1.115-1990, American National Standard for Telecommunications -
           Signaling System Number 7 (SS7) - Monitoring and Measurements for
           Networks
     ANSI T1.116-1990, American National Standard for Telecommunications -
           Signaling System Number 7 (SS7) - Operations, Maintenance and
           Administration Part (OMAP)
     ANSI T1.118-1992, American National Standard for Telecommunications -
           Signaling System Number 7 (SS7) - Intermediate Signaling Network 
           Identification (ISNI)
     Bellcore GR-905-CORE, Common Channel Signaling Network Interface
           Specification (CCSNIS) Supporting Network Interconnection, Message
           Transfer Part (MTP), and Integrated Services Digital Network
           User Part (ISDNUP)
     Bellcore GR-954-CORE, CCS Network Interface Specification (CCSNIS)
           Supporting Line Information Database (LIDB) Service
     Bellcore Special Report SR-TSV-002275, BOC Notes on the LEC Networks-
           Signaling
     Ameritech Supplement AM-TR-OAT-000069, Common Channel Signaling Network
           Interface Specifications
     Bellcore Standard FR-NWT-000476
     ANSI Standard T1.206

     Electrical/Optical Interfaces
     -----------------------------

     Bellcore Technical Publication TR-INS-000342, High Capacity Digital Special
           Access Service, Transmission Parameter Limits and Interface
           Combinations;

                              Sch. 2.3 - 6
<PAGE>
 
      Ameritech Technical Publication TR-NIS-000111, Ameritech 0C3, OC12 and
           OC48 Service Interface Specifications; and
      Ameritech Technical Publication AM-TR-NIS-000133, Ameritech 0C3, OC12 and
           OC48 Dedicated Ring Service Interface Specifications.

 Collocation
 -----------

     Bellcore Network Equipment Building Systems (NEBS) standards TR-EOP-000063
           National Electrical Code (NEC) use latest issue
     TA-NPL-000286, NEBS Generic Engineering Requirements for System Assembly
           and Cable Distribution, Issue 2 (Bellcore, January 1989)
     TR-EOP-000063, Network Equipment-Building System (NEBS) Generic Equipment
           Requirements, Issue 3, March 1988
     TR-NWT-000840, Supplier Support Generic Requirements (SSGR), (A Module of 
           LSSGR, FR-NWT-000064), Issue 1 (Bellcore, December 1991)
     TR-NWT-001275 Central Office Environment Installations/Removal Generic
           Requirements, Issue 1, January 1993
     Institute of Electrical and Electronics Engineers (IEEE) Standard 383, IEEE
           Standard for Type Test of Class 1 E Electrical Cables, Field Splices,
           and Connections for Nuclear Power Generating Stations
     National Electrical Code (NEC) use latest issue
     TA-NPL-000286, NEBS Generic Engineering Requirements for System Assembly
           and Cable Distribution, Issue 2 (Bellcore, January 1989)
     TR-EOP-000063, Network Equipment-Building System (NEBS) Generic Equipment
           Requirements, Issue 3, March 1988
     TR-EOP-000151, Generic Requirements for 24-, 48-, 130- and 140- Volt
           Central Office Power Plant Rectifiers, Issue 1 (Bellcore, May 1985)
     TR-EOP-000232, General Requirements for Lead-Acid Storage Batteries, Issue
           1 (Bellcore, June 1985)
     TR-NWT-000154, General Requirements for 24-, 48-, 130-, and 140- Volt
           Central Office Power Plant Control and Distribution Equipment, 
           Issue 2 (Bellcore, January 1992)
     TR-NWT-000295, Isolated Ground Planes: Definition and Application to
           Telephone Central Offices, Issue 2 (Bellcore, July 1992)
     TR-NWT-000840, Supplier Support Generic Requirements (SSGR), (A Module
     of LSSGR, FR-NWT-000064), Issue 1 (Bellcore, December 1991)
     TR-NWT-001275, Central Office Environment Installations/Removal Generic
           Requirements, Issue 1, January 1993 
     Underwriters' Laboratories Standard, UL 94

                              Sch. 2.3 - 7
<PAGE>
 
                                 SCHEDULE 3.8

               AMERITECH INTERCONNECTION PERFORMANCE BENCHMARKS

1.0   Trunk Provisioning Intervals

      1.1 Number of End Office
          Trunks Per Order Per Day               Interval
          ------------------------               --------
                             1-48                14 days
                             49-96               15 days
                             97+                 Negotiated
 
      1.2 New Trunk Groups to Tandem(s)          Negotiated
          -----------------------------

2.0   Trunking Grade of Service

      Blocking Standards

          Traffic Type                           Measurement
          ------------                           -----------
      Exchange Access Final Trunk Group Traffic  1/2 of 1% (0.005)
          via Tandems
      All Other Final Trunk Group Traffic        1% (0.01)

3.0  Truck Restoral 
     
          Type of Outage                         Interval
          --------------                         --------
      Service Affecting                          within 1 hour
      Non-Service Affecting                      within 24 hours


The Parties agree that additional Interconnection Performance Benchmarks may be
agreed upon by the Implementation Team. However, if any additional
Interconnection Performance Benchmarks require a Party to maintain records which
it then does not maintain, the Party requesting such new or additional
benchmarks shall utilize the Bona Fide Request process with respect to such
records.


                              Sch. 3.8 - 1
<PAGE>
 
                             SCHEDULE 3.9

                                 9-1-1 SERVICE

1.0   STANDARD FEATURES

      1.1. Forced Disconnect. Enables the PSAP attendant to release a connection
           -----------------                                                  
 on a 9-1-1 call, even if the calling party remains off-hook. The time required
to effect the forced disconnect varies as a function of the office type.

      1.2. Default Routing. Default Routing is activated when an incomong 9-1-1 
           ---------------
call cannot be selectively routed due to an ANI failure, garbled digits or other
causes. Such incoming calls are routed from the 9-1-1 Control Office to a
default PSAP if requested by the primary PSAP. Each incoming 9-1-1 facility
group to the Control Office is assigned to a designated default PSAP. Default
ANI and ALI data is provided when a call is Default Routed to indicate such
routing has taken place.

      1.3. Alternate Routing. Alternate Routing allows 9-1-1 calls to be routed
           -----------------
to a designated alternate location if (a) all 9-1-1 Service Lines to the
Primary PSAP are busy, or (b) the Primary PSAP closes down for a period (e.g,
                                                                         ---
night service).

      1.4. Central Office Transfer Arrangements:
           ------------------------------------

          1.4.1.    Manual transfer enables the PSAP attendant to transfer an
incoming call by depressing the switchhook of the associated telephone or the
"add" button on the Display and Transfer Unit and dialing either a 10-
digit telephone number, a 7-digit telephone number or a
2-digit speed calling code.

          1.4.2.    Fixed transfer enables a PSAP attendant to transfer incoming
9-1-1 calls to Secondary PSAPs by use of a single button on the Display and
Transfer Unit.

          1.4.3.    Selective transfer provides the PSAP with the ability to
transfer an incoming call to another responding agency by depressing a single
button labeled with the type of agency (e.g., "FIRE") on the Display and
                                        ---
Transfer Unit. Selective transfer is only available when Selective Routing is
provided.

2.0   9-1-1 MEET POINTS FOR PRIMARY AND DIVERSE ROUTES

      The point of Interconnection for Focal's Primary and Diverse Routes to the
mux/co-location and 9-1-1 Control Offices is at the Ameritech Central Office.
Focal shall pay tariff charges for Diverse routes. Focal will be responsible for
determining the proper quantity of trunks from its End Office(s) to the
Ameritech Central Office(s). Trunks between the Ameritech Central Office and the
Ameritech Control Office shall be delivered by Ameritech within twenty (20)
Business Days


                              Sch. 3.9 - 1
<PAGE>
 
following order by Focal. Following delivery, Focal and Ameritech will cooperate
to promptly test all transport facilities between Focal's network and the
Ameritech Control Office to assure proper functioning of the 9-1-1 service.


                                 Sch. 3.9 - 2
<PAGE>
 
                                 SCHEDULE 6.0

                       MEET-POINT BILLING RATE STRUCTURE

A   Interstate access - Terminating to or originating from Focal Customers
    served from an Focal local exchange End Office.

RATE ELEMENT                 BILLING
                                                 COMPANY

CCL                                              Focal                  
Local Switching                                  Focal
Interconnection charge                           Focal

Local Transport (Tandem) Termination             50% Ameritech
                                                 50% Focal

Local Transport (Tandem) facility                This will calculated based on  
                                                 NECA tariff No. 4 filings for
                                                 each Party
      
Tandem Switching                                 Ameritech      
Entrance Facility                                Ameritech 

B. Intrastate access - Terminating to or originating from Focal Customers served
   from an Focal local exchange End Office.
   
RATE ELEMENT                 BILLING
                                                 COMPANY

CCL                                              Focal
Local Switching                                  Focal
Interconnection Charge                           Focal
                
Local Transport (Tandem) Termination             50% Ameritech
                                                 50% Focal

Local Transport (Tandem) Facility                This will be caculated based 
                                                 on NECA tariff No. 4 filings
                                                 for each Party

     
                              Sch. 6.0 - 1
<PAGE>
 
Tandem Switching                                 Ameritech
Entrance Facility                                Ameritech
 

                                 Sch. 6.0 - 2
<PAGE>
 
                                SCHEDULE 9.2.1

                                 LOCAL LOOPS

      Subject to SECTION 1.1 of SCHEDULE 9.5, Ameritech shall allow Focal to
                 -----------    ------------
access the following Loop types (in addition to those Loops available under
applicable tariffs) unbundled from local switching and local transport.

      "2-WIRE ANALOG VOICE GRADE LOOP" OR "ANALOG 2W," which supports analog
transmission of 300-3000 Hz, repeat loop start, loop reverse battery, or ground
start seizure and disconnect in one direction (toward the End Office Switch),
and repeat ringing in the other direction (toward the Customer) and terminates
in a 2-Wire interface at both the central office MDF and the customer premises.
Analog 2W includes Loops sufficient for the provision of PBX trunks, pay
telephone lines and electronic key system lines. Analog 2W will be provided in
accordance with the specifications, interfaces, and parameters described in
Technical Reference AM-TR-TMO-000122, Ameritech Unbundled Analog Loops.

     "4-WIRE ANALOG VOICE GRADE LOOP" or "ANALOG 4W," which supports
transmission of voice grade signals using separate transmit and receive paths
and terminates in a 4-wire electrical interface at both ends. Analog 4W will be
provided in accordance with the specifications, interfaces, and parameters
described in Technical Reference AM-TR-TMO-000122, Ameritech Unbundled Analog 
Loops.

     "2-WIRE ISDN 160 KBPS DIGITAL LOOP" or "BRI-ISDN" which supports digital
transmission of two 64 Kbps bearer channels and one 16 Kbps data channel (2B+D).
BRI-ISDN is a 2B+D Basic Rate Interface-Integrated Services Digital Network
(BRI-ISDN) Loop which will meet national ISDN standards and conform to Technical
Reference AM-TR-TMO-000123, Ameritech Unbundled Digital Loops (Including ISDN).

     "2-WIRE ADSL-COMPATIBLE LOOP" or "ADSL 2W" is a transmission path which
facilitates the transmission of up to a 6 Mbps digital signal downstream (toward
the Customer) and up to a 640 kpbs digital signal upstream (away from the
Customer) while simultaneously carrying an analog voice signal. An ADSL-2W is
provided over a 2-Wire, non-loaded twisted copper pair provisioned using revised
resistance design guidelines and meeting ANSI Standard T1.413-1995 and AM TR-TM
O-000123. An ADSL-2W terminates in a 2-wire electrical interface at the Customer
premises and at the Ameritech Central Office frame. ADSL technology can only be
deployed over Loops which extend less than 18 Kft. from Ameritech's Central
Office. ADSL compatible Loops are available on1y where existing copper
facilities can meet the ANSI T1.413-1995 specifications.


                             Sch. 9.2.1 - 1
<PAGE>
 
      "2-WIRE HDSL-COMPATIBLE LOOP" OR "HDSL 2W" is a transmission path which
facilitates the transmission of a 768 Kbps digital signal over a 2-Wire, non-
loaded twisted copper pair meeting the specifications in ANSI T1E1 Committee
Technical Report Number 28. HDSL compatible Loops are available only where
existing copper facilities can meet the T1E1 Technical Report Number 28 and
AM-TR-TMO-000123 specifications.

      "4-WIRE HDSL-COMPATIBLE LOOP" OR "HDSL 4W" is a transmission path which
facilitates the transmission of a 1.544 Mbps digital signal over two 2-Wire,
non-loaded twisted copper pairs meeting the specifications in ANS1 T1E1 
Committee Technical Report Number 28 and AM TR-TMO-000123. HDSL compatible Loops
are available only where existing copper facilities can meet the T1E1 Technical
Report Number 28 specifications.

     "4-WIRE 64 KBPS DIGITAL LOOP" OR "4-WIRE 64 DIGITAL" is a transmission path
which supports transmission of digital signals of up to a maximum binary
information rate of 64 Kbps and terminates in a 4-Wire electrical interface at
both the Customer premises and on the MDF in Ameritech's Central Office. 4-Wire
64 Digital will be provided in accordance with the specifications, interfaces
and parameters described in AM-TR-TM-000123.

     "4-WIRE 1.554 MBPS DIGITAL LOOP" OR "1.544 MPBS DIGITAL" is a transmission
path which supports transmission of digital signals of up to a maximum binary
information rate of 1.544 Mpbs and terminates in a 4-Wire electrical interface
at the Customer premises and on the DSX frame in Ameritech's Central Office.
1.544 Mbps Digital will be provided in accordance with the specifications,
interfaces and parameters described in AM-TR-TMO-00023.


                             Sch. 9.2.1 - 2
<PAGE>
 
                                SCHEDULE 9.2.2
 
                 UNBUNDLED ACCESS TO NETWORK INTERFACE DEVICES
 
     Ameritech's Network Interface Device ("NID") is a Network Element that
utilizes a cross-connect device to connect loop facilities to inside wiring.
 
     Ameritech will permit Focal to connect Focal's loop to the inside wiring of
the Customer's premises through Ameritech's NID, where necessary. Focal must
establish the connection to Ameritech's NID through an adjoining NID which
serves as the network interface or demarcation for Focal's loop.

     Maintenance and control of premises (inside wiring)is under the control of
the Customer. Any conflicts between service providers for access to the
Customer's inside wire must be resolved by the Customer.
 

                                  Sch.9.2.2-1
<PAGE>
 
                                SCHEDULE 9.2.3


                             SWITCHING CAPABILITY


1.0   LOCAL SWITCHING. The local switching capability of a Network Element is
      defined as:

      (1)  line-side facilities, which include the connection between a Loop
           termination at the Main Distribution Frame and a switch line card;

      (2)  trunk-side facilities, which include the connection between trunk
           termination at a trunk-side cross-connect panel and a switch trunk
           card; and

      (3)  all features, functions, and capabilities of the switch available
           from the specific port type (line side or trunk side port), which
           include:

                (a) the basic switching function of connecting lines to lines,
           lines to trunks, trunks to lines, and trunks to trunks, as well as
           the same basic capabilities made available to Ameritech's Customers,
           such as a telephone number, white page listing, and dial tone;

                (b) access to operator services, directory assistance and 9-1-1
           and

                (c) all other features that the switch provides, including
           custom calling, CLASS features and Centrex, as well as any
           technically feasible customized routing functions available from such
           switch.

When local switching is provided by Ameritech, Focal will receive Customer Usage
Data and billing information in accordance with the requirements of SECTION
                                                                    -------
10.16.
-----
     
2.0  TANDEM SWITCHING
     
     2.1   The Tandem Switching Capability Network Element is defined as:

     (1)   an unbundled Network Element in Ameritech's Class 4 non-TOPS digital
           Tandem Switches, which includes Interconnection with the trunk at the
           Tandem Distribution Frame ("TDF") and the Tandem Switch trunk ports.

     (2)   the basic switching function of creating a temporary transmission
           path that connects Focal's trunks to the trunks of Ameritech, IXCs,
           ICOs, CMRS, and other LECs interconnected to the Tandem Switch.


                                Sch. 9.2.3 - 1
<PAGE>
 
     2.2 Interconnecting trunk types which can be switched include FGB, FGC, FGD
and Type II. Signaling support includes Rotary, MF, and SS7 and any signaling
conversions between these signaling formats.

     2.3 Variations in Tandem Switching equipment used to provide service in
specific locations may cause differences in the operation of certain features.

     2.4 The unbundled Tandem Switching Network Element will provide to Focal
all available basic Tandem Switching functions and basic capabilities that are
centralized in the Tandem Switch (and not in End Office Switches), including the
following functions Ameritech makes available to its Customers:

1.   Routing of calls from an inbound trunk to an outbound trunk based on
     destination digits.

     2     Routing of Equal Access or Operator Service calls from an inbound
           trunk to an outbound trunk based on the CIC forwarded by the inbound
           trunk.

     2.5 Translations, screening, blocking, and route indexing are provided if
technically feasible under the standard switching translations and screening in
use in that switch. A request for translations, screening, blocking, route
indexing other than what is available (i.e., features that the switch is capable
                                       ---
of providing) in that switch will be provided where technically feasible as a
Bona Fide Request. Ameritech will provide these features if technically feasible
and upon agreement by Focal to pay the applicable recurring and nonrecurring
costs of developing, installing, providing and maintaining the capability.
Variations in the Tandem Switching equipment or translation and screening used
to provide service in specific locations may cause differences in the operation
of the element.

                             S c h. 9.2.3 - 2
<PAGE>
 
                                SCHEDULE 9.2.4

                      INTEROFFICE TRANSMISSION FACILITIES

      Interoffice Transmission Facilities are Ameritech transmission facilities
dedicated to a particular Customer or carrier, or shared by more than one
Customer or carrier, used to provide Telecommunications Services between Wire
Centers owned by Ameritech or Focal, or between Switches owned by Ameritech or
Focal.

1.    Ameritech provides several varieties of unbundled transport facilities:

      1.1. Unbundled dedicated interoffice transport facility ("DEDICATED
TRANSPORT") is a dedicated facility connecting two Ameritech Central Offices
buildings via Ameritech transmission equipment. In each Central Office building,
Focal will Cross-Connect this facility to its own transmission equipment
(physically or virtually) Collocated in each Wire Center, or to other unbundled
Network Elements provided by Ameritech to the extent the requested combination
is technically feasible and is consistent with other standards established by
the FCC for the combination of unbundled Network Elements. All applicable
digital Cross-Connect, multiplexing, and Collocation space charges apply at an
additional cost.

      1.2. "Unbundled dedicated entrance facility" is a dedicated facility
connecting Ameritech's transmission equipment in an Ameritech Central Office
with Focal's transmission equipment in Focal's Wire Center for the purposes of
providing Telecommunications Services.

      1.3. Shared transport transmission facilities ("SHARED TRANSPORT") are a
billing arrangement where two (2) or more carriers share the features, functions
and capabilities of transmission facilities between the same types of locations
as described for dedicated transport in SECTIONS 1.1 and 1.2 preceding and
                                        ------------     ---
share the costs.

2.   Ameritech shall offer Interoffice Transmission Facilities in each of the
following ways:

     2.1   As a dedicated transmission path (e.g., DS1, DS3, OC3, OC12 and OC48)
                                             ---
dedicated to Focal.

     2.2   As a shared transmission path as described in SECTION 1.3 above.
                                                         -----------

                                Sch. 9.2.4 - 1
<PAGE>
 
3.   Where Dedicated Transport or Shared Transport is provided, it shall include
     (as appropriate):

     3.1. The transmission path at the requested speed or bit rate.

     3.2. The following optional features are available; if requested by Focal,
at additional cost:

           3.2. 1. Clear Channel Capability per 1.544 Mpbs (DS1) bit stream.

           3.2.2. Ameritech provided Central Office multiplexing:

                  (a)  DS3 to DS1 multiplexing; and

                  (b)  DS1 to Voice/Base Rate/128, 256, 384 Kpbs Transport
                       multiplexing.

     3.3  If requested by Focal, the following are available at an additional
cost:

          3.3.1.  1+1 Protection for OC3, OC12 and OC48.

          3.2.2.  1+1 Protection with Cable Survivability for OC3, OC12 and
                  OC48.

          3.3.3.  1+1 Protection with Route Survivability for OC3, OC12 and
                  OC48.

 4.   Technical Requirements.

      This Section sets forth technical requirements for all Interoffice
      Transmission Facilities:

      4.1. When Ameritech provides Dedicated Transport as a circuit, the entire
designated transmission facility (e.g., DS1, DS3, and where available, STS-1)
shall be dedicated to Focal designated traffic.

      4.2. Ameritech shall offer Dedicated Transport in all then currently
available technologies including, DS1 and DS3 transport systems, SONET Bi-
directional Line Switched Rings, SONET Unidirectional Path Switched Rings, and
SONET point-to-point transport systems (including linear add-drop systems), at
all available transmission bit rates, except subrate services, where available.

      4.3. For DS1 facilities, Dedicated Transport shall, at a minimum, meet
the performance, availability, jitter, and delay requirements specified for
Customer Interface to Central Office "CI to CO" connections in the applicable
technical references set forth under Dedicated and Shared Transport in the
Technical Reference Schedule.

      4.4. For DS3 and, where available, STS-1 facilities and higher rate
 facilities, Dedicated Transport shall, at a minimum, meet the performance,
 availability, jitter, and delay requirements specified for Customer Interface
 to Central Office "CI to CO" connections in the applicable

                                Sch. 9.2.4 - 2
<PAGE>
 
 technical references set forth under Dedicated and Shared Transport in the
 Technical Reference Schedule.

     4.5. When requested by Focal, Dedicated Transport shall provide physical
diversity. Physical diversity means that two circuits are provisioned in such a
way that no single failure of facilities or equipment will cause a failure on
both circuits.

     4.6. When physical diversity is requested by Focal, Ameritech shall
provide the maximum feasible physical separation between intra-office and inter-
office transmission paths (unless otherwise agreed by Focal).

     4.7. Any request by Focal for diversity shall be subject to additional
charges.

     4.8. Upon Focal's request and its payment of any additional charges,
Ameritech shall provide immediate and continuous remote access to performance
monitoring and alarm data affecting, or potentially affecting, Focal's traffic.

     4.9.  Ameritech shall offer the following interface transmission rates for
Dedicated Transport:

           4.9.1. DS1 (Extended SuperFrame - ESF, D4, and unframed applications
     (if used by Ameritech)):

           4.9.2. DS3 (C-bit Parity and M13 and unframed applications (if used
     by Ameritech) shall be provided):

           4.9.3. SONET standard interface rates in accordance with the
     applicable ANSI technical references set forth under Dedicated and Shared
     Transport in the Technical Reference Schedule. In particular, where STS-1
     is available, VT 1.5 based STS-Is will be the interface at an Focal
     service node.

     4.10. Upon Focal's request, Ameritech shall provide Focal with electronic
provisioning control of an Focal specified Dedicated Transport through Ameritech
Network Reconfiguration Service (ANRS) on the rates, terms and conditions in
F.C.C. Tariff No.2.

     4.11. Ameritech shall permit, at applicable rates, Focal to obtain the
functionality provided by DCS together with and separate from dedicated
transport in the same manner that Ameritech offers such capabilities to IXCs
that purchase transport services. If Focal requests additional functionality,
such request shall be made through the Bona Fide Request process.


                             Sch. 9.2.4 - 3
<PAGE>
 
                                SCHEDULE 9.2.5

                 SIGNALING NETWORKS AND CALL-RELATED DATABASES

1.0   SIGNALING TRANSFER POINTS.

      A Signaling Transfer Point (STP) is a signaling network function that
includes all of the capabilities provided by the signaling transfer point
switches (STPSs) and their associated signaling links which enable the
exchange of SS7 messages among and between switching elements, database
elements and signaling transfer point switches.

1.1. TECHNICAL REQUIREMENTS.

     1.1.1. STPs shall provide access to all other Network Elements connected to
Ameritech SS7 network. These include:


            1.1.1.1.     Ameritech Local Switching or Tandem Switching;

            1.1.1.2.     Ameritech Service Control Points/Databases;

            1.1.1.3.     Third-party local or tandem switching systems, and
   
            1.1.1.4.     Third-party-provided STPSs.

     1.1.2.  The connectivity provided by STPs shall ful1y support the functions
of all other Network Elements connected to the Ameritech SS7 network. This
explicitly includes the use of the Ameritech SS7 network to convey messages
which neither originate nor terminate at a Signaling End Point directly
connected to the Ameritech SS7 network (i.e., transient messages). When the
                                        ---
Ameritech SS7 network is used to convey transient messages, there shall be no
alteration of the Integrated Services Digital Network User Part (ISDNUP) or
Transaction Capabilities Application Part (TCAP) user data that constitutes the
content of the message.


     1.1.3. If an Ameritech Tandem Switch routes calling traffic, based on
dialed or translated digits, on SS7 trunks between an Focal local switch and
third party local switch, the Ameritech SS7 network shall convey the TCAP
messages that are necessary to provide Call Management features (Automatic
Callback, Automatic Recall, and Screening List Editing) between the Focal local
STPSs and the STPSs that provide connectivity with the third party local switch,
even if the third party local switch is not directly connected to the Ameritech
STPSs, based on the routing instruction provided in each message.


                                Sch. 9.2.5 - 1
<PAGE>
 
      1.1.4. STPs shall provide all functions of the MTP as specified in ANSI
             T1.111. This includes:

             1.1.4.1. Signaling Data Link functions, as specified in 
                      ANSI T1.111.2:

             1.1.4.2. Signaling Link functions, as specified in ANSI T1.111.3;
                      and

             1.1.4.3. Signaling Network Management functions, as specified in
                      ANSI T1.111.4.

      1.1.5. STPs shall provide all functions of the SCCP necessary for Class 0
(basic connectionless) service, as specified in ANSI T1.112. In particular, this
includes Global Title Translation (GTT) and SCCP Management procedures, as
specified in T1.112.4. In cases where the destination signaling point is an
Ameritech local or tandem switching system or database, or is an Focal or third
party local or tandem switching system directly connected to the Ameritech SS7
network, STPs shall perform final GTT of messages to the destination and SCCP
Subsystem Management of the destination. In all other cases, STPs shall perform
intermediate GTT of messages to a gateway pair of STPSs in an SS7 network
connected with the Ameritech SS7 network, and shall not perform SCCP Subsystem
Management of the destination.

      1.1.6. STPs shall also provide the capability to route SCCP messages based
on ISNI, as specified in ANSI T1.118, when this capability becomes available on
Ameritech STPSs.

      1.1.7. STPs shall provide all functions of the OMAP commonly provided
by STPSs. This includes:

             1.1.7.1. MTP Routing Verification Test (MRVT); and

             1.1.7.2. SCCP Routing Verification Test (SRVT).

      1.1.8. In cases where the destination signaling point is an Ameritech
local or tandem switching system or database, or is an Focal or third party
local or tandem switching system directly connected to the Ameritech SS7
network, STPs shall perform MRVT and SRVT to the destination signaling point. In
all other cases, STPs shall perform MRVT and SRVT to a gateway pair of STPSs in
an SS7 network connected with the Ameritech SS7 network. This requirement shall
be superseded by the specifications for Internetwork MRVT and SRVT if and when
these become approved ANSI standards and available capabilities of Ameritech
STPSs.

      1.1.9. STPs shall be equal to or better than the following performance
             requirements:

             1.1.9.1. MTP Performance, as specified in ANSI T1.111.6; and

             1.1.9.2. SCCP Performance, as specified in ANSI T1.1125.


                                Sch. 9.2.5 - 2
<PAGE>
 
1.2.  SIGNALING LINK TRANSPORT.

      1.2.1. Definition. Signaling Link Transport is a set of two (2) or four
(4) dedicated 56 Kbps transmission paths between Focal-designated Signaling
Points of Interconnection (SPOI) that provides appropriate physical diversity.

Technical Requirements.

      1.2.2. Signaling Link Transport shall consist of full duplex mode 56 Kbps
transmission paths.

      1.2.3. Of the various options available, Signaling Link Transport shall
perform the following two (2) ways:


             a) As an "A-link" which is a connection between a switch or SCP and
             a Signaling Transfer Point Switch (STPS) pair; and

             b) As a "D-link" which is a connection between two (2) STP mated
             pairs in different company networks (e.g., between two (2) STPS
                                                  ---
             pairs for two Competitive Local Exchange Carriers (CLECs)).

      1.2.4. Signaling Link Transport shall consist of two (2) or more signaling
link layers as follows:

             a)   An A-link layer shall consist of two (2) links.

             b)   A D-link layer shall consist of four (4) links.

      1.2.5. A signaling link layer shall satisfy a performance objective such
that:

             a)   There shall be no more than two (2) minutes down time per year
                  for an A-link layer; and

             b)   There shall be negligible (less than two (2) seconds) down
                  time per year for a D-link layer.

      1.2.6. A signaling link layer shall satisfy interoffice and intraoffice
diversity of facilities and equipment, such that:

             a)   No single failure of facilities or equipment causes the
             failure of both links in an A-link layer (i.e., the links should be
                                                       ---          
             provided on a minimum of two (2) separate physical paths end-to-
             end); and


                                Sch. 9.2.5 - 3
<PAGE>
 
           b)   No two (2) concurrent failures of facilities or equipment shall
           cause the failure of all four (4) links in a D-link layer (i.e., the
                                                                      ---
           links should be provided on a minimum of three (3) separate physical
           paths end-to-end).

    1.2.7. Interface Requirements. There shall be a DS1 (1.544 Mbps) interface
at the Focal-designated SPOI. Each 56 Kbps transmission path shall appear as a
DSO channel within the DS1 interface.

    2.1.   TOLL FREE DATABASE SERVICES.

    2.1.1. Call Routing Service. The Call Routing Service provides for the
           --------------------
identification of the carrier to whom a call is to be routed when a toll-free
(1+800-NXX-XXXX or 1+888-NXX-XXXX) call is originated by Customer. This function
uses the dialed digits to identify the appropriate carrier and is done by
screening the full ten digits of the dialed number. The Call Routing Service may
be provided in conjunction with a Customer's InterLATA or IntraLATA Switched
Exchange Access Service.

      When 800 Call-Routing service is provided, an originating call is
suspended at the first switching office equipped with a Service Switching Point
(SSP) component of the SSC/SS7 Network. The SSP launches a query over signaling
links (A-links) to the Signal Transfer Point (STP), and from there to the SCP.
The SCP returns a message containing the identification of the carrier to whom
the call should be routed and the call is Processed.

      Focal's SS7 network is used to transport the query from its End Office to
the Ameritech SCP. Once Focal's identification is provided, Focal may use the
information to route the toll-free traffic over its network. In these cases,
Ameritech Switched Access services are not used to deliver a call to Focal. The
toll-free carrier ID data may not be stored for Focal's future use.

      2.1.2. Routing Options. In addition to the toll-free service offerings, 
             ---------------
new routing options are offered. These options are purchased by toll-free
service providers to allow their clients to define complex routing requirements
on their toll-free service. Toll-free routing options allow the service
provider's Customer to route its toll-free calls to alternate carriers and/or
destinations based on time of day, day of week, specific dates or other
criteria. These routing options are in addition to the basic toll-free call
routing requirements which would include the toll-free number, the intraLATA
carrier, the interLATA carrier and the Area of Service (AOS).

      2.1.3. Carrier Identification. Focal may choose the 800 Carrier
             ----------------------
Identification service to obtain toll-free number screening. With this service,
Focal will launch a query to the Ameritech database using its own Service
Switching Points (SSPs) network. In contrast to the Call Routing Service
described in Section 2.1.1 above, with the 800 Carrier Identification service,
             -------------
no routing is performed.

      2.1.4. Number Administration. Focal, at its option, may elect to use
             ----------------------                                       
Ameritech's toll-free Service which includes toll-free Number Administration
Service (NAS). With this service,


                                Sch. 9. 2.5 - 4
<PAGE>
 
Ameritech will perform the Responsible Organization service, which involves
interacting, with the national Service Management System (SMS/800), on behalf of
the Customer. Responsible Organization services include activating, deactivating
and maintaining 800/888 number records as well as trouble referral and
clearance. If Focal does not select NAS, Focal will perform the Responsible
Organization service.

     2.2.   LIDB DATABASE SERVICE.

     2.2.1. The Line Information Database (LIDB) Query Response Service is a
validation database system. It enables Focal to offer alternately billed
services to its Customers. The database provides an efficient way to validate
calling cards and toll billing exception (TBE) (i.e., restricts a collect or
                                                ---
third-party billed call). Toll fraud protection and reduced call set up expenses
are among the benefits of the service.

     2.2.2. Billing information records include the Customer name, phone number
security personal identification numbers and third-party acceptance indications.
Prior to call completion, a query is launched to the LIDB to determine the
validity of the requested billing method. The call is then completed or denied
based on the LIDB's response.

     2.3.   CNDS DATABASE SERVICE.

            2.3.1 Caller ID identifies a calling party's telephone number
            through a switch-based feature installed in Ameritech's Central
            Office. CNDS is a CCIS/SS7 network based feature that accesses a
            CNDS database within the LIDB to provide a name associated with the
            calling party's telephone number. This service is provided using TR
            1188 protocol.

            2.3.2 A Customer who subscribes to Caller ID with Name will see the
            listed name associated with the calling party's telephone line
            displayed on his/her Caller ID display unit. The telephone number
            associated with the telephone line of the calling party will also be
            displayed.

            2.3.3 Ameritech shall charge Focal for the CNDS Database Service in
            a similar manner to that which Ameritech charges Focal for the LIDB
            Database Service, including a per query charge.

     2.4    LOCAL NUMBER PORTABILITY.

            2.4.1 Ameritech's provision of LNP will utilize LRN switch software
     based on requirements developed by the workshop participants and concurred
     in by the Commission. These requirements are fully compliant with the
     principles adopted by the FCC in its First Report and Order, CC Docket No.
     95-116 (the "Number Portability Order"). The detailed description and
     technical specifications for the planned LRN implementation can be found in
     various documents produced by the FCC Local Number Portability workshop.


                                Sch. 9.2.5 - 5
<PAGE>
 
          2.4.2 Ameritech is fully prepared to provide LNP database access to
     Focal. However, in adopting its Number Portability Order, the FCC referred
     certain technical and other issues to the North American Numbering Council
     (NANC) and issued a further notice addressing the recovery of costs
     associated with LNP implementation. Until these activities are concluded,
     Ameritech cannot finalize product descriptions and rates for access to its
     LNP database. Nonetheless, Ameritech is willing to begin discussions with
     Focal to discuss Focal's access to Ameritech's LNP databases in lieu of
     constructing Focal's own.

     2.5. UNBUNDLED AIN APPLICATION PROCESS.

     2.5.1. The AIN architecture establishes a network infrastructure in which
subscriber services can be defined and implemented independent from End-Office
Switches. This is accomplished by a combination of SS7 signaling, interfaces
between Network Elements and call-state models through which AIN Network
Elements interact.

     2.5.2. Ameritech's Unbundled AIN (Advanced Intelligent Network)
Applications Access service will be provided on a nondiscriminatory basis and
enable Focal (whether it purchases unbundled switching capabilities from
Ameritech or owns its own SSP (Service Switching Point)) to offer its Customers
AIN services. Ameritech will make available existing AIN retail applications, as
well as newly created services that Focal creates via the Ameritech AIN Service
Creation Environment (SCE) Access service. Unbundled AIN Applications Access
provides for the AIN functionality necessary for the day to day ongoing call
processing associated with a specific AIN applications execution. This includes
the SS7 transport and SCP processing of the query associated with the specific
service.

     2.5.3. Associated with the AIN SCP is a Service Creation Environment (SCE)
and a Service Management System (SMS). Ameritech offers access to the Ameritech
SMS and SCE capabilities via two (2) AIN offerings: AIN Service Creation
Environment Access Service and AIN Service Management System Access Service.

     2.5.4. Carriers will share the common AIN infrastructure components
provided by Ameritech, such as a Service Control Point (SCP), a Signaling
Transfer Point (STP), Service Management System (SMS), and, if Focal purchases
Unbundled Switching from Ameritech, the AIN Service Switching Point (SSP). Focal
shall be responsible for assuring the compatibility of its AIN SSP software
generics with the Ameritech AIN Applications and SCP software releases.
Interconnection of the Focal SSP with the Ameritech SS7 network is required, and
can be accomplished in a number of ways.

     2.5.5. Activation of the desired application at the Ameritech SCP requires
subscription by both the ordering carrier Focal and the end-user. In general,
AIN operations require close cooperation between Ameritech and the requesting
Carrier.

                                Sch. 9.2.5 - 6
<PAGE>
 
     2.5.6. The SSP AND SCP vendors provide logical capabilities which Ameritech
uses to create each AIN service. The SSP and SCP vendors have no knowledge of
the specific AIN Applications that Ameritech has created. Ameritech's AIN
deployment is based on AIN 0.1

     3.1.   AIN SERVICE CREATION ENVIRONMENT ACCESS SERVICE.

Access to Ameritech's AIN service creation functionality will be provided in a
nondiscriminatory manner to Focal to enable it to create new AIN services on
Ameritech's network. If Focal has a new AIN service concept, it can utilize all
or some of the features below to obtain a fully functional AIN service.
Ameritech will furnish Focal with a list of AIN Applications and the switches on
which such applications are available, including the software version of AIN on
such switch type. The following is a list of AIN service creation functions
available via this service offering:

            
     3.1.1. Service Concept Description: The description of service idea should
detail requirements such as: dialing patterns, information exchange,
announcements, voice prompts, expected service management screens and reports,
and CPE requirements. The AIN service creation functions made available to Focal
must be the same ones Ameritech uses, subject to any third party restrictions
Ameritech may be subject to.

     3.1.2. Creation of Technical Specification: Translation of a new service
description into a technical specification including engineering requirements
for Ameritech's network. The technical specification must detail how the service
interacts in the network, translated in network terms, should include any
expected/anticipated feature interaction discrepancies, and will include the
process flows on how the service traverses the network.

     3.1.3. Service Logic Design: The development of service design from SCP
perspective to include Algorithms, Data Structures and Flow Diagrams.

     3.1.4. Service Logic Coding: Development of machine logic in the SCE to
include tables, SIBBs, and other elements as necessary.

     3.1.5. Service Logic Testing: Service logic testing isolated within the to
SCE to ensure accuracy of compilation and code development and compliance with
Ameritech's AIN environment.

     3.1.6. SMS Interface Requirements: Development of Focal SMS interface
access including screens, flow-through interface and reports. This is required
to allow Focal to activate, update, modify, and administer Customer data
associated with the new service.

     3.1.7. Platform Access Logic Configuration: Service specific updates to
global infrastructure required to enable new service. Includes modification of
the access logic to enable a new service.

     3.1.8. Service Integration Testing (SIL): Intensive laboratory testing of
service in conjunction with all Ameritech Switch types and or provider switch
types and generics (as

                                Sch. 9.2.5 - 7
<PAGE>
 
necessary) to minimize potential feature interaction conflicts and negative
network reactions. Resources must be made available to Focal on a
nondiscriminatory basis.

     3.1.9.  Network Implementation: Conditioning of the SMS, SCP, SSP, or STP
to accept service including network translations, signaling connectivity,
dialing plans, and coordination of provisioning process.

                         
     3.1.10. Field Testing: Comprehensive controlled testing in a live switch
environment, possibly at Focal's SSP location.

     3.2.    AIN SERVICE MANAGEMENT SYSTEM ACCESS SERVICE.

                                                     
     3.2.1.  Access to Ameritech's AIN service management system functionality
will be provided in a nondiscriminatory manner to Focal to enable it to manage
AIN services located wholly within Ameritech's network (SCP & SSP) or to manage
AIN services where the service logic is located within Ameritech's SCP and the
Customer is served from Focal's AIN-compatible SSP. Upon request of Focal,
Ameritech shall provide Focal the unbundled AIN Applications Access service
product description and a list of existing Ameritech AIN applications.

     3.2.2.  The Service Management System (SMS) is the administration system
for the service logic and data in the Advanced Intelligent Network (AIN) Service
Control Point (SCP). The SMS contains the master copy of service level,
subscriber level and subscription level data. The SMS also contains a copy of
the service logic.

Logical access to the SMS will be managed by a set of programs designed by
Ameritech. These programs provide security for the data that resides on the AIN
platforms by allowing user access to only specific data that is appropriate to
the customer or carrier. Whether explicitly stated in this document or not, all
access to the SMS is managed through these programs. The only exceptions to
managed access to SMS functionality are for the Ameritech Network Services
organizations that administer the AIN platforms. They require direct access in
order to appropriately administer the platforms.

Mediated access to SMS functionality will be provided through interface programs
that will be developed for specific services. Focal will have access to all of
the data that the service requires in order to administer that service for its
Customers. This includes service level, subscriber level, and subscription level
data as well as any reports and measurement data that is mutually agreed upon by
Ameritech and Focal.

     3.2.3. Service Logic. The SMS receives a copy of the service logic and
service management logic from the Service Creation Environment (SCE) system.
After population of specific network level and service level data, the SMS
downloads a view of the service logic to the designated SCPs. The service
management logic remains in the SMS to complement SMS utilities in the
monitoring and administration of a specific service.

                                Sch. 9.2.5 - 8
<PAGE>
 
It is required that all of the Service Creation unit testing, System Integration
Lab (SIL) testing and Network Deployment Testing has been completed.

It may be necessary for Focal to negotiate timing and supply service specific
data before that service can be deployed in the appropriate SCPs. Ameritech,
however, is totally responsible for service logic deployment and initial SCP
memory load in its network. Focal will receive timing and supply of service
specific data in a nondiscriminatory manner.

     3.2.4. Service Administration. Service administration involves the
management of service level data which the service logic requires for its
execution. SMS supports the management of service specific common data. Any
changes to the data representation of the Ameritech network, which impact one or
more carrier services will be administered by Ameritech. Other Focal specific or
service specific data changes will be identified and administered by Focal.

                                Sch. 9.2.5 - 9
<PAGE>
 
                                SCHEDULE 9.2.6

                     OPERATIONS SUPPORT SYSTEMS FUNCTIONS

1.0  PRE-ORDERING, ORDERING AND PROVISIONING. Ameritech will use the interface
described in Section 10.13.2(a) (including the separate interface used for
             ------------------
ordering prior to the first quarter of 1997) for the transfer and receipt of
data necessary to perform the pre-ordering, ordering, and provisioning functions
(e.g., order entry, telephone number and due date selection). However, the
 ----
Access Services Request (ASR) interface will be used for the transfer of
information concerning the Network Elements and Combinations which Focal intends
to order in a specific Wire Center ("FOOTPRINT" or "TRUNK SIDE INFORMATION").

2.0  MAINTENANCE AND REPAIR. Ameritech will use the interface described in
SECTION 10.13.3 (A) for the transfer and receipt of data necessary to perform
---------------
the maintenance and repair functions (e.g., trouble receipt and trouble status).
                                      ---

3.0   BILLING. Ameritech will provide appropriate usage data to Focal to
facilitate Customer billing with attendant acknowledgments and status reports
and exchange information to process claims and adjustments.

                                Sch. 9.2.6 - 1
<PAGE>
 
                                SCHEDULE 9.2.7

                   OPERATOR SERVICES AND DIRECTORY SERVICES

1.0 OPERATOR SERVICES. Operator Services consist of the following services.

      1.1  Manual Call Assistance - manual call processing with operator
           ----------------------
involvement for the following:

           (a) Calling card - the Customer dials 0+ or 0- and provides operator
     with calling card number for billing purposes.

           (b) Collect - the Customer dials 0+ or 0- and asks the operator to
     bill the call to the called number, provided such billing is accepted by
                                         --------
     the called number.

           (c) Third number billed - the Customer dials 0+ or 0- and asks the
     operator to bill the call to a different number than the calling or called
     number.

           (d)  Operator assistance - providing local and intraLATA operator
     assistance for the purposes of:

                (1) assisting Customers requesting help in completing calls or
                    requesting information on how to place calls;

                (2) handling emergency calls;

                (3) handling credits and coin telephone local refund requests;
                    and

                (4) handling person-to-person calls.

           (e)  Operator Transfer Service ("OTS") - calls in which the Customer
     dials "0", is connected to an Ameritech operator and then requests call
     routing to an IXC subscribing to OTS. The operator will key the IXC's digit
     carrier identification code to route the Customer to the requested IXC's
     point of termination.

           (f)  BLV - Service in which operator verifies a busy condition on a
     line.

           (g)  BLVI - service in which operator, after verifying a busy line,
     interrupts the call in progress.

                                Sch. 9.2.7 - 1
<PAGE>
 
      1.2  Automated Call Assistance - mechanized call processing without 
           -------------------------
operator involvement for the following:

           (a) Automated calling card service ("ACCS") - the Customer dials 0
      and a telephone number, and responds to prompts to complete the billing,
      information.

           (b) Automated Alternate Billing Service ("AABS") -

               (1)  the Customer dials 0 and a telephone number and responds to
                    prompts to process the call and complete the billing
                    information (Customer branding not currently available).

               (2)  ACCS calculates charges, relates the charge to the Customer,
                    and monitors coins deposited before connecting the 1 +
                    intraLATA or interLATA call.

      1.3  Line Information Database ("LIDB") Validation - mechanized queries to
           --------------------------------------------- 
a LIDB for billing validation.

      1.4  Database Access - To the extent technically feasible, Ameritech will
           ---------------
provide access to databases used in the provisioning of Operator Services via
Focal's Bona Fide Request.

2.0   DIRECTORY ASSISTANCE. Directory Assistance ("DA") service shall consist of
the following services.

      2.1  Directory Assistance - those calls in which the Customer dial digits
           --------------------
designated by Focal to obtain Directory Assistance for local numbers located
within his/her NPA. Two listings will be provided per call.

      2.2  Branding - the ability to put messages on the front end of a DA call
           --------                                                           
that is directly trunked into Ameritech's DA switch.

      2.3  Information Call Completion - provides a Customer who has accessed
           ---------------------------
the DA service and has received a number from the Audio Response Unit ("ARU")
the option of having an intraLATA call completed by pressing a specific digit on
a touch tone telephone. Information Call Completion is only available to Focal
if it direct trunks its DA calls to Ameritech.

      2.4  Upon request, and through a technically feasible arrangement,
Ameritech will provide access to databases used in the provisioning of DA via
Focal's Bona Fide Request at rates that recover Ameritech's costs of developing,
providing and maintaining the service. Such unbundled access to the DA database
shall be for the purpose of having Focal's Telephone Exchange Service DA listing
in the area placed into Ameritech's DA database, or to enable Focal to read DA
listing in the database so that Focal can provide its own DA service.

                                Sch. 9.2.7 - 2
<PAGE>
 
3.0   RATE APPLICATION. Ameritech shall bill Focal the applicable rates on a
monthly basis, in accordance with the following methodology.

      3.1 Manual Call Assistance - operator call occurrences multiplied by the
          ----------------------                                             
per call rate. Total call occurrences shall include all processed calls, whether
or not they are completed.

      3.2 Automated Call Assistance (ACCS and AABS) - call occurrences
          -----------------------------------------
multiplied by the per call occurrence rate. Total call occurrences shall include
all processed calls, whether or not they are completed.

      3.3 LIDB Validation - validation occurrences mulitplied by the LIDB 
          ---------------
validation per occurrence rate. Total validation occurrences shall include all
validations, whether or not the call is completed. Ameritech will accumulate
operator occurrences, automated occurrences, and LIDB validation occurrences via
its Operator Services Call Analysis System ("OSCAS"). OSCAS utilizes TOPS AMA
recordings to produce monthly summaries of mecahnized and manual call
occurrences.

      3.4 BLV - operator call occurrences multiplied by the per call rate. Total
          ---
call occurrences shall include all processed calls whether or not they are 
completed.

      3.5 BLVI - operator call occurrences multiplied by the per call rate. 
          ----
Total call occurrences shall include all processed calls whether or not they are
completed.

      3.6 Lost Records. If Ameritech is responsible for lost, destroyed, or
          ------------
mutilated TOPS AMA recordings, Ameritech will not bill Focal for those calls for
which there are no records. Likewise, Ameritech shall not be held responsible by
Focal for lost revenue. However, if within ninety (90) days, actual data should
become available, Ameritech will bill Focal for those calls using actual data.

                                Sch. 9.2.7 - 3
<PAGE>
 
                                SCHEDULE 9.3.4

                                 COMBINATIONS


1.    Unbundled Element Platform with Operator Services and Directory Assistance
      --------------------------------------------------------------------------

Unbundled Loop
Local Switching
Operator Services and Directory Assistance
Shared Transport
Dedicated Transport
STPs
Signaling Link Transport
Service Control Points (SCPs)/Databases
Tandem Switching

2.    Loop Combination
      ----------------

Unbundled Loop
Network Interface Device

3.    Switching Combination #1
      ------------------------

Shared Transport
Dedicated Transport
STPs
Signaling Link Transport
Service Control Points (SCPs)/Databases
Tandem Switching

                                Sch. 9.3.4 - 1
<PAGE>
 
                                SCHEDULE 9.3.5

               COMBINATIONS AVAILABLE THROUGH BONA FIDE REQUEST

1.    Loop/Network Combination
      ------------------------

Unbundled Loop
Shared Transport
Dedicated Transport
STPs
Signaling Link Transport
Service Control Points (SCPs)/Databases
Tandem Switching

2.    Switching Combination #2
      ------------------------

Network Interface Device
Local Switching
Shared Transport
Dedicated Transport
SS7 Message Transfer & Connection Control
Signaling Link Transport
Service Control Points (SCPs)/Databases
Tandem Switching

3.    Switching Combination #3
      ------------------------

Network Interface Device
Local Switching
Operator Systems
Shared Transport
Dedicated Transport
SS7 Message Transfer & Connection Control
Signaling Link Transport
Service Control Points (SCPs)/Databases
Tandem Switching

                                Sch. 9.3.5 - 1
<PAGE>
 
4.    Switched Data Services
      ----------------------

Network Interface Device
Local Switching
Shared Transport
Dedicated Transport
Tandem Switching

5.    Unbundled Element Platform Without Operator Services and Directory
      ------------------------------------------------------------------
      Assistance
      ----------

Unbundled Loop
Local Switching
Shared Transport
Dedicated Transport
STPs
Signaling Link Transport
Service Control Points (SCPs)/Databases 
Tandem Switching

                                Sch. 9.3.5 - 2
<PAGE>
 
                                 SCHEDULE 9.5

                       PROVISIONING OF NETWORK ELEMENTS

1.0  GENERAL PROVISIONING REQUIREMENTS.

     1.1  Subject to the terms of Article IX, Focal may order and/or request
                                  ----------
          Elements either individually or as Combinations.

     1.2  The Combinations set forth on SCHEDULE 9.3.4 and any additional
                                        --------------
          Combination provided previously hereunder by Ameritech pursuant to
          the Bona Fide Request process shall be identified and described by
          Focal so that they can be ordered and provisioned as a Combination
          and shall not require the enumeration of each Network Element within
          that Combination on each provisioning order, provided that in each
                                                       --------            
          case Focal shall specify on each order the type of service to be
          provided as well as the engineering and routing characteristics
          (e.g. redundancy requirements and data transfer rates) Focal 
           ---  
          requests for such Combination.

     1.3  Focal may order from Ameritech multiple individual Network Elements on
          a single order without the need to have Focal send an order for each
          such Network Element if such Network Elements are (i) for a single
          type of service, (ii) for a single location and (iii) for the same
          account.

     1.4  Ameritech shall provide provisioning services to Focal Monday through
          Friday from 8:00 a.m. to 5:00 p.m. CST. Focal may request Ameritech to
          provide Saturday, Sunday, holiday, and/or off-hour provisioning
          services. If Focal requests that Ameritech perform provisioning
          services at times or on days other than as required in the preceding
          sentence, Ameritech shall quote, within three (3) Business Days of the
          request, a cost-based rate for such services. If Focal accepts
          Ameritech's quote, Ameritech shall perform such provisioning services.

     1.5  Ameritech shall provide a Single Point of Contact (each, a SPOC) for
          ordering and provisioning contacts and order flow involved in the
          purchase and provisioning of Ameritech's unbundled Network Elements or
          Combinations. The SPOCs shall provide an electronic interface twenty-
          four (24) hours a day, seven (7) days a week for all ordering and
          provisioning order flows. Each SPOC shall also provide to Focal a 
          toll-free nationwide telephone number (operational from 8:00 a.m. to 5
          p.m., Monday through Friday) which will be answered by capable staff
          trained to answer questions and resolve problems in connection with
          the provisioning of Network Elements or Combinations.

     1.6  Ameritech shall provide to Focal a single point of contact (the
          "UNBUNDLING ORDERING CENTER") for ordering unbundled Network Elements.
          A national toll-

                                 Sch. 9.5 - 1
<PAGE>
 
            free number will be provided from 7:00 a.m. to 5:00 p.m. CST,
            Monday through Friday. This Unbundling Ordering Center is
            responsible for order acceptance, order issuance, and return of the
            Firm Order Commitment (FOC) to Focal as specified in this Schedule
            9.5.

            In addition, Ameritech shall provide to Focal a single point of
            contact (the "UNBUNDLING SERVICE CENTER") for all provisioning,
            maintenance, repair, and cutover coordination. A national toll-free
            number will be provided from 6:30 a.m. to 12:00 a.m. CST Monday
            through Friday. Out of hours maintenance questions are handled by a
            "FOLD DOWN CENTER."

      1.7   Ameritech will recognize Focal as the Customer of Record of all
            Network Elements and agreed to Combinations ordered by Focal and
            will send all notices, invoices and pertinent Customer information
            directly to Focal.

      1.8   Ameritech may not initiate any disconnection or rearrangement of any
            Focal ordered Element or Combination, except as directed by Focal or
            as otherwise provided in this Agreement.

      1.9   When requested by Focal, Ameritech will schedule installation
            appointments with Ameritech's representative on the line with
            Focal's representative until Focal has access to Ameritech's
            scheduling system.

      1.10  Ameritech will provide Focal with a Firm Order Confirmation (FOC)
            for each order, within twenty-four (24) hours of Ameritech's receipt
            of that order, or within a different time interval agreed upon by
            the Implementation Team. The FOC must contain an enumeration of
            Focal's ordered Network Elements or Combination features, options,
            physical Interconnection, quantity, and Ameritech commitment date
            for order completion ("COMMITTED DUE DATE"), which commitment date
            shall be established on a nondiscriminatory basis with respect to
            installation dates for comparable orders at such time.

      1.11  Upon work completion, Ameritech will provide Focal electronically
            (unless otherwise notified by Focal) with an order completion per
            order that states when that order was completed. Ameritech shall
            respond with specific order detail as enumerated on the FOC and
            shall state any additional charges (e.g. time and materials charges)
                                                ---
            up to a previously agreed upon limit associated with that order.

                                 Sch. 9.5 - 2
<PAGE>
 
      1.12  Ameritech will perform pre-testing of Network Elements and
            Combinations in accordance with Ameritech's standards. At Focal's
            request, Ameritech will make available to Focal on a weekly batch
            basis any available test and turn-up results in support of the
            Network Elements or Combinations ordered by Focal. Focal shall be
            responsible for any costs incurred by Ameritech to provide copies of
            any available results. If Focal requests Ameritech to provide Focal
            with any test or turn-up results which Ameritech does not then
            generate, Focal shall request such results through the Bona Fide
            Request process.

      1.13  As soon as identified, Ameritech shall provide notification
            electronically of Focal orders that are incomplete or incorrect and
            therefore cannot be processed.

      1.14  As soon as identified, Ameritech shall provide notification
            electronically of any instances when Ameritech's Committed Due Dates
            are in jeopardy of not being met by Ameritech on any element or
            feature contained in any order for Network Elements or Combinations.
            Ameritech shall indicate its new committed due date as soon as such
            date is available.

      1.15  Within twenty-four (24) hours of Focal's request, Ameritech will
            perform cooperative testing with Focal (including trouble shooting
            to isolate any problems) to test Network Elements or Combinations
            purchased by Focal in order to identify any performance problems.

      1.16  Subject to ARTICLE IX, Network Elements and Combinations will be
                       --------                                             
            provisioned with a combination of customer-specific and bulk orders
            as specified by Focal.

      1.17  When Focal orders Network Elements or Combinations that are
            currently interconnected and functional and remain interconnected to
            the same adjacent Network Elements, such Network Elements and
            Combinations will remain interconnected and functional without any
            disconnection or disruption of functionality of such Network
            Elements. There shall be no charge for such interconnection.
            Consequently, for Ameritech retail Customers who simply wish to
            switch their local service providers and keep the same type of
            service provided through the same equipment, this method of ordering
            will accomplish this with no physical changes required in the
            existing Network Elements. Under these circumstances, it shall not
            be necessary for Focal to collocate equipment in Ameritech Central
            Offices to connect the unbundled Network Element. If shared Network
            Elements are used, Ameritech will be responsible for all
            engineering, provisioning and maintenance of these components to
            ensure they support the agreed-upon grade of service.

                                 Sch. 9.5 - 3
<PAGE>
 
      1.18  Ameritech shall provide to Focal upon request:

            (a) a list of all services and features technically available from
                each switch that Ameritech may use to provide Local Switching,
                by switch CLLI;

            (b) a listing by street address detail, of the service coverage area
                of each switch CLLI;

            (c) when available, all engineering design and layout information
                for each Network Element and Combination; provided that Focal 
                                                          --------
                shall pay Ameritech for the costs incurred by Ameritech to
                provide Focal with copies of such information;

            (d) a listing of all technically available functionalities for each
                Network Element or Combination; and

            (e) advanced information on the details and requirement for planning
                and implementation of NPA splits.

      1.19  Promptly after the Effective Date, /22/ Ameritech shall provide 
                                                --
Focal
                                                
            an initial electronic copy of the following information:

            (a) Street address verification; 
            (b) Switch identification by service address; and 
            (c) Switch feature verification.

            Electronic updates to such information shall be provided monthly to
            Focal as changes are made to such information.

      1.20  For orders of Network Elements (and INP with the installation of a
Loop) that require coordination among Ameritech, Focal and Focal's Customer,
Focal shall be responsible for any necessary coordination with the Focal
Customer.

2.0   UNBUNDLED LOCAL LOOP TRANSMISSION

      2.1   ACCESS TO UNBUNDLED LOCAL LOOPS.

            2.1.1 Focal shall access Ameritech's Unbundled Local Loops via
     Collocation or in accordance with Article IX of this Agreement at the
                                       ----------
     Ameritech Wire Center where that


_________________________

/22/ Since the terms of this Agreement are the result of Focal's adoption under
 --                                                                             
     Section 252(i) of the Act of the AT&T Agreement, the Parties agree that the
     term "Effective Date", for purposes of this SECTION 1.19 OF SCHEDULE 9.5,
                                                 ------------    ------------
     shall mean February 10, 1999.

                                 Sch. 9.5 - 4
<PAGE>
 
     element exists and each Loop shall be delivered to Focal's Collocation by
     means of a CrossConnection, which shall be an additional charge.

            2.1.2 Ameritech shall provide Focal access to its unbundled Loops at
     each of Ameritech's Wire Centers. In addition, if Focal requests one or
     more Loops serviced by Integrated Digital Loop Carrier or Remote Switching
     technoloy deployed as a Loop concentrator, Ameritech shall, where
     available, move the requested Loop(s) to a spare, existing physical Loop at
     no charge to Focal. If, however, no spare physical Loop is available,
     Ameritech shall within forty-eight (48) hours of Focal's request notify
     Focal of the lack of available facilities. Focal may then at its discretion
     make a Bona Fide Request for Ameritech to provide the unbundled Loop
     through the demultiplexing of the integrated digitized Loop(s).
     Notwithstanding anything to the contrary in this Agreement, the
     provisioning intervals set forth in SECTION 2.2.2 of this Schedule and the
                                         -------------
     Ameritech Network Element Performance Benchmarks set forth in SCHEDULE 9.10
                                                                   -------------
     of this Agreement shall not apply to unbundled Loops provided under this
     SECTION 2.1.2.
     -------------

            2.1.3 If Focal orders a Loop type and the distance requested on such
     Loop exceeds the transmission characteristics as referenced in the
     corresponding Technical Reference specified below, distance extensions may
     be requested where technically feasible to meet the specification using
     such distance extensions and additional rates and charges shall apply as
     set forth at Item V of the Pricing Schedule.

              Loop Type                     Technical Reference/Limitation

Electronic Key Line                      2.5 miles
ISDN                                     Bellcore TA-NWT-000393
HDSL 2W                                  T1E1 Technical Report Number 28
HDSL 4W                                  T1E1 Technical Report Number 28
ADSL 2W                                  ANSI T1.413-1995 Specification


2.2  PROVISIONING OF UNBUNDLED LOOPS.

     The following coordination procedures shall apply for conversions of "LIVE"
Telephone Exchange Services to unbundled Network Elements:

            2.2.1 Focal shall request unbundled Loops from Ameritech by
     delivering to Ameritech a valid electronic transmittal service order (a
     "SERVICE ORDER") using the electronic interface described on SCHEDULE 
                                                                  --------
     9.2.6. Within twenty-four (24) hours of Ameritech's receipt of a Service
     -----
     Order, Ameritech shall provide Focal the firm order

                                 Sch. 9.5 - 5
<PAGE>
 
      commitment ("FOC") date according to the applicable Ameritech Network
      Element Performance Benchmarks set forth in SECTION 9.10 of this Agreement
                                                  ------------
      by which the Loop(s) covered by such Service Order will be installed.

            2.2.2 Ameritech shall provision unbundled Loops in accordance with
     the time frames set forth on SCHEDULE 9.10 or within such other intervals
                                  -------------                              
     as agreed upon by the Parties.

            2.2.3 Ameritech agrees to coordinate with Focal at least forty-eight
     (48) hours prior to the due date a scheduled conversion date and time (the
     "SCHEDULED CONVERSION TIME") in the "A.M." (12:00 midnight to 12:00 noon)
     or "P.M." (12:00 noon to 12:00 midnight) (as applicable, the "CONVERSION
     WINDOW").

            2.2.4 Not less than one (1) hour prior to the Scheduled Conversion
     Time, either Party may contact the other Party and unilaterally designate a
     new Scheduled Conversion Time (the "NEW CONVERSION TIME"). If the New
     Conversion Time is within the Conversion Window, no charges shall be
     assessed on or waived by either Party. If, however, the New Conversion Time
     is outside of the Conversion Window, the Party requesting such New
     Conversion Time shall be subject to the following:

            If Ameritech requests the New Conversion Time, the applicable Line
            Connection Charge shall be waived; and

            If Focal requests the New Conversion Time, Focal shall be assessed a
            Line Connection Charge in addition to the Line Connection Charge
            that will be incurred for the New Conversion Time.

            2.2.5 Ameritech shall test for Focal dial-tone ("DIAL TONE TEST") at
     Ameritech's MDF for Focal's Virtual Collocated equipment or Physical
     Collocated equipment during a window not greater than forty-eight (48)
     hours but not less than eight (8) hours prior to the Scheduled Conversion
     Time (or New Scheduled Time, as applicable). Ameritech shall perform the
     Dial Tone Test at no charge until the termination of this Agreement.

            2.2.6 Except as otherwise agreed by the Parties for a specific
     conversion, the Parties agree that the time interval expected from
     disconnection of "LIVE" Telephone Exchange Service to the connection of an
     unbundled Network Element at the Focal Collocation interface point will be
     sixty (60) minutes or less. If a conversion interval exceeds sixty (60)
     minutes and such delay is caused solely by Ameritech (and not by a Delaying
     Event), Ameritech shall waive the applicable Line Connection Charge for
     such element. If Focal has ordered INP with the installation of a Loop,
     Ameritech will coordinate the implementation of INP with the Loop
     conversion during the sixty (60) minute interval at no additional charge.

                                 Sch. 9.5 - 6
<PAGE>
 
            2.2.7 Requests for maintenance or repair of unbundled Loops are
      initiated using the industry standard "electronic bonding" interface (EBI)
      and are handled by the Ameritech Unbundling Service Center ("USC"). The
      USC works with local Ameritech personnel to perform any manual testing
      that may be required to isolate the trouble.

3.0   NETWORK INTERFACE DEVICE CAPABILITY.

      3.1   Ameritech will provide Focal access to NIDs in a manner that will
permit Focal to connect its loop facilities to the Customer's inside wiring
through Ameritech's NID, as required. Focal shall establish this connection
through an adjoining NID provided by Focal.

      3.2   Due to the wide variety of NIDs utilized by Ameritech (based on
Customer size and environmental considerations), Focal may access the Customer's
inside wire by any of the following means:

                                                            
            (a) Where an adequate length of inside wire is present and
            environmental conditions permit, Focal may remove the inside wire
            from Ameritech's NID and connect that wire to Focal's NID;

            (b) Enter the Customer access chamber or "side" of "dual chamber"
            NID enclosures for the purpose of extending a connecterized or
            spliced jumper wire from the inside wire through a suitable "punch-
            out" hole of such NID enclosures;

            (c) Enter Ameritech's loop terminal enclosure located at a multiple
            dwelling unit ("MDU") for the purpose of accessing Customer
            premises inside wire and extending such wire to Focal's own
            adjoining NID; or

            (d) Request Ameritech to make other rearrangements to the inside
            wire terminations or terminal enclosure on a time and materials cost
            basis to be charged to the requesting party (i.e., Focal, its agent,
                                                         ---
            the building owner or the Customer).

      3.3   If Focal accesses the Customer's inside wire as described in SECTION
                                                                         -------
2.2(D), the time and materials charges will be billed to the requesting party
------
(i.e., Focal, the building owner or the Customer).
 ---

      3.4   In no case shall Focal remove or disconnect Ameritech's loop
facilities from Ameritech's NIDs, enclosures, or protectors.

      3.5   In no case shall Focal remove or disconnect ground wires from
Ameritech's NIDs, enclosures, or protectors.

      3.6   Maintenance and control of premises wiring (inside wire) is the 
responsibility of the Customer. Any conflicts between service providers for 
access to the Customer's inside wire must be resolved by the Customer.

                                 Sch. 9.5 - 7
<PAGE>
 
      3.7   Due to the wide variety of NID enclosures and outside plant
environments, Ameritech will work with Focal to develop specific procedures to
establish the most effective means of implementing this SECTION 3.0.
                                                        -----------
4.0   UNBUNDLED LOCAL SWITCHING

      4.1   Access to Unbundled Local Switching.
            -----------------------------------

            4.1.1 Focal shall access Ameritech's Unbundled Local Switching via
      Collocation or in accordance with ARTICLE IX of this Agreement at the
                                        ----------
      Ameritech Wire Center where that element exists and each line-side and/or
      trunk-side port will be delivered to Focal's Collocation by means of a
      Cross-Connection, which shall be an additional charge.

            4.1.2 Ameritech shall provide Focal access to its Unbundled Local
      Switching at each of Ameritech's Wire Centers and will provide Focal all
      available basic local switching functions and basic capabilities the
      switch is capable of providing which Ameritech currently makes available
      to its local Customers, or for which Ameritech OSS functions are capable
      of provisioning pursuant to a Bona Fide Request.

            4.1.3 Unbundled Local Switching also provides access to additional
      features and capabilities that the switch has available for activation.
      Focal has the capability of activating these features on a line-by-line
      basis via an electronic interface. The additional features available for
      activation on the basic Unbundled Local Switching include:

                  (a)  vertical features;
                  (b)  Custom Calling, Custom Local Area Signaling Service
                       features ("CLASS") features; and
                  (c)  Centrex features.

            4.1.4 Other basic and/or additional capabilities, functions and
      features that are not then available for activation on the switch may be
      requested as optional special capabilities. Ameritech will provide these
      special capabilities if technically feasible and upon Focal's Bona Fide
      Request. Focal will pay the applicable recurring and nonrecurring costs of
      developing, installing, providing and maintaining the requested
      capability.

            4.1.5 Unless already provided by Ameritech as a service offering,
     and if not, upon Focal's Bona Fide Request, Ameritech will provide any
     technically feasible customized local routing of traffic through Unbundled
     Local Switching by class of call (e.g., operator, directory assistance, 
                                       ----
     9-1-1, toll, local, etc.). Ameritech will develop and provide any requested
     customized routing the switch is capable of providing, upon agreement by
     Focal to pay recurring and nonrecurring costs of developing, installing,
     updating, providing and maintaining such custom routing.

                                 Sch. 9.5 - 8
<PAGE>
 
            4.1.6 Ameritech provides, on an optional basis, the ability to
     connect line-side ports and/or trunk-side ports within the same switch with
     a group of common attributes. An example, is a request for Unbundled Local
     Switching to provide a Centrex service with intercom calling within the
     system and with certain common features. The attributes available include
     intercom calling, group call pick-up, and Automatic Route Selection.
     Intercom calling is defined as the ability of the line-side ports to call
     one another by dialing 3-7 digits. Group call pick up is defined as
     allowing one line-side port to answer a call directed to another line-side
     port in the same call pick-up group. ARS is defined as the ability to route
     calls to a specific group of trunk-side ports.

            4.1.7 Ameritech will switch traffic through its local switching
     element in accordance with Ameritech standard switching translations and
     screening in use in that switch. The custom routing optional feature
     enables Focal to specify special routing, by class of call, of some or all
     traffic incoming into its unbundled local switch using any technically
     feasible routing capability of that switch. Variations in the End Office
     switching equipment used to provide service in specific locations may cause
     differences in the operation of certain features. Special routing
     capabilities that are not otherwise available (i.e., features that the
                                                    ----
     switch is capable Of providing) will be developed on an individual basis
     through the Bona Fide Request process and will be installed, updated,
     maintained and provided following Focal's agreement to pay the applicable
     costs.

     4.2    PROVISIONING OF UNBUNDLED LOCAL SWITCHING.

     The following coordination Procedures shall apply for conversions of "LIVE"
Telephone Exchange Services to unbundled Network Elements:

            4.2.1 Focal shall request Unbundled Local Switching from Ameritech
     by delivering to Ameritech a valid electronic transmittal service order (a
     "SERVICE ORDER") using the electronic interface described on SCHEDULE
                                                                  --------    
     9.2.6. In addition, pre-ordering functions are supported via electronic
     -----
     data interchange (EDI) format as utilized for Resale Services. Within
     twenty-four (24) hours of Ameritech's receipt of a Service Order, Ameritech
     shall provide Focal the firm order commitment ("FOC") date by which the
     Unbundled Local Switching ports covered by such Service Order will be
     installed.

               Where connection of the Unbundled Local Switching port(s) to
     customized routing is required by Focal, the specific custom routing
     pattern desired must already exist. In those instances where the custom
     routing pattern does not already exist, Focal may request the development
     and establishment of such customer routing, pattern via a Bona Fide
     Request. While the custom routing pattern is being developed, Focal may do
     one of the following: (a) defer activation of the Unbundled Local Switching
     port until the routing pattern is established, (b) offer the Customer
     resale on an interim basis, or (c) convert the existing basic office
     routing pattern. If Focal elects option (c) and later desires to convert
     the Unbundled Local Switching port using Ameritech's office routing
     pattern to a customized routing pattern, an additional Line Connection
     Charge will apply.


                              Sch. 9.5 - 9
<PAGE>
 
            4.2.2 Ameritech agrees to coordinate with Focal at least forty-eight
     hours prior to the due date a scheduled conversion date and time (the
     "SCHEDULED CONVERSION TIME") in the "A.M." (12:00 midnight to 12:00 noon)
     or "P.M." (12:00 noon to 12:00 midnight) (as applicable, the "CONVERSION
     WINDOW").

            4.2.3 Not less than one (1) hour prior to the Scheduled
     Conversion Time, either Party may contact the other Party and unilaterally
     designate a new Scheduled Conversion Time (the "NEW CONVERSION TIME"). If
     the New Conversion Time is within the Conversion Window, no charges shall
     be assessed on or waived by either Party. If, however, the New Conversion
     Time is outside of the Conversion Window, the Party requesting such New
     Conversion Time shall be subject to the following:

            If Ameritech requests the New Conversion Time, the applicable Line
            Connection charge shall be waived; and
            

            If Focal requests the New Conversion Time, Focal shall be assessed a
            Line Connection charge in addition to the Line Connection Charge
            that will be incurred for the New Conversion Time.

            4.2.4 Except as otherwise agreed by the Parties for a specific
     conversion, the Parties agree that the time interval expected from
     disconnection of "LIVE" Telephone Exchange Service to the connection of an
     unbundled Network Element at the Focal Collocation interface point will be
     sixty (60) minutes or less. If a conversion interval exceeds sixty (60)
     minutes and such delay is caused solely by Ameritech (and not by a Delaying
     Event), Ameritech shall waive the applicable Line Connection Charge for
     such element.

            If Focal has ordered INP with the installation of a Loop, Ameritech
     will coordinate the implementation of INP with the Loop conversion during
     the sixty (60) minute interval at no additional coordination charge (other
     than the applicable standard service order and line connection charges).

     Ameritech shall provide to Focal equivalent functionality of blocking calls
     (e.g.,900, 976 and international calls) as provided to Ameritech's retail
      ----    
    Customers.

            4.2.5 When ordering a Local Switching Element, Focal may order from
     Ameritech separate interLATA and intraLATA capabilities (i.e., 2 PICs where
                                                              ---
     available) on a line or trunk basis.

            4.2.6 Unless otherwise directed by Focal and to the extent
     technically feasible, when Focal orders a Network Element or Combination,
     all pre-assigned trunk or telephone numbers currently associated with that
     Network Element or Combination shall be retained without loss of feature
     capability.


                             Sch. 9.5 - 10
<PAGE>
 
     4.3    Tandem Switching.
            ----------------

            4.3.1 Tandem Switching creates a temporary transmission path
     between interoffice trunks that are interconnected at a switch for the
     purpose of routing a call or calls. Unbundled Tandem Switching is ordered
     using electronic interfaces. Trunk-side ports are ordered using the Access
     Service Request ("ASR") which provides for electronic ordering based on
     industry standards adopted through OBF. ASR is the process used as of the
     Effective Date to order Exchange Access Services. Both pre-ordering and
     ordering functions and access to associated Operations Support Systems
     functions are supported electronically through these interfaces.

            4.3.2 Ameritech will service, operate, and maintain the unbundled
     Tandem Switching for Focal at parity with the service, operation, and
     maintenance Ameritech provides to itself, its subsidiaries, Affiliates and
     any other person. Unless requested otherwise, where applicable and
     technically feasible, Ameritech will provide unbundled Tandem Switching
     using the same specifications, interfaces, parameters, intervals,
     procedures and practices it uses to provide comparable Tandem Switching for
     all other Customers and carriers. Any feature or function existing in the
     Tandem Switch will be provided to Focal on a non-discriminatory basis.
     Congestion control and overflow routing will be provided on a non-
     discriminatory basis.

            4.3.3 Tandem Switching performance will be measured to ensure parity
     with all other Telecommunications Carriers that are interconnected with
     Ameritech. Performance will be measured on switching, call recording, and
     network management controls.

            4.3.4 Switch downtime will be measured through FCC reportable
     incidents report. CPI Index will be measured calls blocked and customer out
     of service incidents.

            4.3.5 Electronic Billing Accuracy Centers (EBAC) measures billing
     errors from the CABS error hold file report. Ameritech employs RAVE/A&T
     which enables on-line investigation of AMA volumes and will alert EBAC to
     possible AMA recording failures.

            4.3.6 Congestion Control and overflow criteria are set by the use of
     NTMOS Surveillance system which polls EDAS and NMA data on call volumes
     and make busy standards. Ameritech sets automatic thresholds with preplan
     routing and overflow selection. The system is also monitored via a manual
     surveillance system early recognition of performance problems.

                             Sch. 9.5 - 11
<PAGE>
 
5.0   INTEROFFICE TRANSMISSION FACILITIES.

      Ameritech shall:

      5.1 Provide Focal exclusive use of Interoffice Transmission Facilities
dedicated to Focal, or use of the features, functions, and capabilities of
Interoffice Transmission Facilities shared by more than one Customer or carrier,
including Focal;

      5.2 Provide all technically feasible transmission facilities, features,
functions, and capabilities that Focal could use to provide Telecommunications
Services;

      5.3 Permit, to the extent technically feasible, Focal to connect such
interoffice facilities to equipment designated by Focal, including Focal's
Collocated facilities; and

      5.4 Permit, to the extent technically feasible, Focal to obtain the
functionality provided by Ameritech's digital cross-connect systems separate
from dedicated transport.

6.0   SIGNALING NETWORKS AND CALL-RELATED DATABASES

      6.1  Signaling, Networks.
           -------------------

           6.1.1 If Focal purchases Switching Capability from Ameritech,
      Ameritech shall provide access to its signaling work from that switch in
      the same manner which Ameritech obtains access to such switch itself. In
      addition, Ameritech shall provide Focal access to Ameritech's signaling
      network for each of Focal's switches when Focal uses its own switching
      facilities. This connection shall be made in the same manner as Ameritech
      connects one of its own switches to an STP. Notwithstanding the foregoing,
      Ameritech shall not be required to unbundle those signaling links that
      connect Service Control Points to STPs or to permit Focal to link its own
      STPs directly to Ameritech's switch or call-related databases.

           6.1.2  If Focal has its own switching facilities, Ameritech shall
      provide Focal access to STPs to each of Focal's switches, in the same
      manner in which Ameritech connects one of its own switches to an STP, or
      in any other technically feasible manner (e.g., bringing an "A" link from
                                                ----
      Focal's switch to Ameritech's STP, or linking Focal's switch to its own
      STP and then connecting that STP to Ameritech's STP via a "B" or "D"
      link); provided that Ameritech shall not be required to (i) unbundle the
      signaling link connecting SCPs to STPs, (ii) permit direct linkage of
      Focal's own STPs to Ameritech's switch or call-related databases or (iii)
      unbundle an SCP from its associated STP.

           6.1.3  The Parties shall agree upon appropriate mediation facilities
      and arrangements for the Interconnection of their signaling networks and
      facilities, as necessary to adequately safeguard against intentional and
      unintentional misuse of the signaling networks and facilities of each
      Party. Such arrangements shall provide at a minimum:
      
                                 Sch. 9.5 - 12
<PAGE>
 
          .     Certification that Focal's switch is compatible with Ameritech's
                SS7 network;

          .     Certification that Focal's switch is compatible with Ameritech's
                AIN SCP;

          .     Certification that Focal's switch is compatible with a desired
                AIN application residing on Ameritech's SCP;

          .     Agreement on procedures for handling maintenance and
                troubleshooting related to AIN services;

          .     Usage of forecasts provided by Focal, so that Ameritech can
                provide suffficient SS7 resources for Focal and
                all other requesting Carriers;

          .     Mechanisms to control signaling traffic at agreed-upon levels,
                so that Ameritech's SS7 resources can be fairly shared by
                all requesting carriers;

          .     Mechanisms to restrict signaling traffic during testing
                and certification, as  necessary to minimize risks to the
                service quality experienced by Customers served by
                Ameritech's network and those of other carriers while
                compatibility and interconnection items are verified; and

          .     Mechanisms to ensure protection of the confidentiality of
                Proprietary Information of both carriers and Customers.

     6.2   Call-Related Databases.
           ----------------------

           6.2.1 For purposes of switch query and database response through a
     signaling network, Ameritech shall provide Focal access to its call-related
     databases, including the Line Information Database, Toll Free Calling
     database, downstream number portability databases, and Advanced intelligent
     Network databases by means of physical access at the STP linked to the
     unbundled database.

           6.2.2 If Focal purchases Unbundled Local Switching, Focal may, upon
     request, use Ameritech's SCP in the same manner, and via the same signaling
     links, as Ameritech. If Focal has deployed its own switch, and has linked
     that switch to Ameritech's signaling system, Focal shall be given access to
     Ameritech's SCP in a manner that allows Focal to provide any call- related,
     database-supported services to Customers served by Focal's switch. If the
     Implementation Team is unable to agree in the Implementation Plan to
     appropriate mediation mechanisms with respect to access to the AIN SCPs,
     the Parties shall adopt the mechanisms adopted by the Commission. Ameritech
     shall provide Focal access to call-related databases in a manner that
     complies with the CPNI requirements of Section 222 of the Act.

                             Sch. 9.5 - 13
<PAGE>
 
        6.2.3  The Parties shall agree upon appropriate mediation facilities
     arrangements for the Interconnection of their signaling networks,
     databases, and associated facilities, as necessary to adequately safeguard
     against intentional and unintentional misuse of the signaling networks and
     facilities of each Party. Such arrangements shall provide for at a minimum:

           .   Capabilities to protect each Party's information;
               
           .   Agreements on handling maintenance and troubleshooting related
               to AIN services;
               
           .   Usage forecasts provided by Focal so that Ameritech can provide
               sufficient resources for other requesting carriers, and
               capabilities to ensure that the Parties abide by such forecasts;
               
               
           .   Procedures to ensure, prior to deployment, that each service
               will properly operate within Ameritech's network;
               
           .   Procedures to verify proper deployment of each service in the
               network; and
               
           .   Mechanisms to ensure protection of the confidentiality of
               proprietary information of both carriers and customers.

      6.3  Service Management Systems.
           --------------------------

           6.3.1 Ameritech shall provide Focal with the information necessary to
     enter correctly, or format for entry, the information relevant for input
     into Ameritech's Service Management System ("SMS"). In addition, Ameritech
     shall provide Focal equivalent access to design, create, test, and deploy
     Advanced Intelligent Network.

           6.3.2 Access will provided in an equivalent manner to that which
     Ameritech currently uses to provide such access to itself (e.g.,
                                                                --- 
     submitting magnetic tapes if Focal inputs magnetic tapes, or through an
     electronic interface equivalent to that used by Focal). The Implementation
     Team shall set forth in the Implementation Plan the terms and conditions
     relating to such access. If the Implementation Team is unable to agree to
     appropriate mediation mechanisms with respect to access to the AIN SMSs and
     SCEs, the Parties shall adopt the mechanisms adopted by the Commission.

           6.3.3  Ameritech shall provide access to its SMS in a manner that
     complies with the CPNI requirements of Section 222 of the Act.

                             Sch. 9.5 - 14
<PAGE>
 
 7.0  OPERATIONS SUPPORT SYSTEMS FUNCTIONS

      7.1  Ameritech shall provide Focal access to Operations Support Systems
functions on or before the dates set forth on the Implementation Schedule.

      7.2  Ameritech shall also provide Focal access to the functionality of any
internal gateway systems Ameritech employs in performing the above-listed OSS
functions for its own Customers. A "gateway system" means any electronic
interface Ameritech has created for its own use in accessing support systems for
providing any of the above-listed OSS functions.

 8.0  OPERATOR SERVICES AND DIRECTORY SERVICES.

      8.1  Ameritech shall provide Focal access to Ameritech's Operator Service
and Directory Assistance facilities where technically feasible.

      8.2  Ameritech shall provide unbundled Operator Services ("OS") and
Directory Assistance ("DA") to Focal in conjunction with Telephone Exchange
Service provided to Focal as a purchaser of Resale Services and as an Unbundled
Local Switching Network Element or directly as a separate Network Element. A
list identifying the NPA/Exchange areas of Ameritech Directory Assistance, and
dependent Information Call Completion services will be provided to Focal and
will be updated as such DA services are provided in additional NPA/Exchange
Areas.

      8.3  Focal will obtain any required custom routing and obtain or provide
the necessary direct trunking and termination facilities to the mutually agreed
upon meet point with Ameritech facilities for access to unbundled OS and DA
services. Focal is responsible for delivering its OS and DA traffic to
Ameritech's operator service switch. Specifically, Focal shall deliver its
traffic direct from the End Office to the operator service switch location, and
there can be no Tandem Switching for OS. The operator service location to which
Focal will deliver its OS or DA traffic will be determined by Ameritech based on
the existing capacity of its service centers. Ameritech will, if technically
feasible, enable Focal to deliver its OS or DA traffic to the operator service
switch most closely located to the Focal's NPA/exchange originating the call.

      8.4  Ameritech will provide and maintain the equipment at its OS and DA
centers necessary to perform the services under this Agreement, with the goal of
ensuring that the OS and DA service meets current industry standards.

      8.5  Ameritech will provide OS and DA in accordance with its then current
internal operating procedures and/or standards.

      8.6  Ameritech will maintain a quality of service that will satisfy the
standards, if any, established by the Commission having Jurisdiction over the
provision of such service. Focal has the right, once annually, to visit each
Ameritech owned or subcontracted office upon reasonable notice to Ameritech or
with greater frequency by mutual consent of the Parties. Upon request, Ameritech

                             Sch. 9.5 - 15
<PAGE>
 
will provide monthly system results regarding speed of answer, average work time
and, for DA only, abandon from queue measurements.

      8.7  Focal is solely responsible for providing all equipment and
facilities to deliver OS and DA traffic to the point of Interconnection with
Ameritech facilities.

      8.8  Focal will provide and maintain the equipment at its offices
necessary to permit Ameritech to perform its services in accordance with the
equipment operations and traffic operations which are in effect in Ameritech's
DA and OS offices. Focal will locate, construct, and maintain its facilities to
afford reasonable protection against hazard and interference.

      8.9  Upon request and to the extent technically feasible, Ameritech will
unbundle OS and DA from resellers of its Telephone Exchange Service, and for
Focal, so Focal can provide its own OS or DA service or obtain it from a third
party. Also, upon request, Ameritech will provide unbundled OS and/or DA as a
stand alone unbundled Network Element to Focal. In either case, Focal is
required to obtain any required custom routing and to arrange for or provide
other facilities, services and Network Elements necessary to deliver its OS and
DA traffic to Ameritech's designated office, or to the office of another
provider, as applicable.

      8.10 Upon request, and as technically feasible, Ameritech will provide
through an electronic interface, unbundled access to its databases used to
provide DA and OS for purpose of enabling Focal to provide its own OS or DA
service, or as otherwise authorized by the FCC or the Commission. Such
unbundled access to DA and OS databases is provided as is technically feasible
based upon the facilities, equipment and software involved, and upon agreement
by Focal to pay to Ameritech its costs of developing, installing, providing and
maintaining such Network Element.

      8.11 Specifically, upon request, Ameritech will provide through an
electronic interface, unbundled access to its DA database to permit Focal to
have its local exchange directory assistance listings in the areas incorporated
into the database, and/or to read the DA listing (with the exception of non-
published listing) in that database for the purpose of providing its own DA
service. Such unbundled access will be provided in a technically feasible manner
based upon the facilities, equipment and software involved, and upon agreement
by Focal to pay to Ameritech its costs of developing, installing, providing and
maintaining such network element.
           
      8.12 Access of resellers and Focal to DA and OS of Ameritech, and the DA
and OS Network Elements provided hereunder, whether provided on a bundled or
unbundled basis, will, as applicable and as feasible, be provided through the
standard interfaces, parameters, intervals, service descriptions, protocols,
procedures, practices and methods that Ameritech uses for other customers of its
DA and OS services. Upon request, Ameritech will, as technically feasible,
provide a different quality of service, upon agreement by Focal to pay to
Ameritech its costs of developing, installing, maintaining maintaining and
repairing access to and provision of the Network Element at such quality of
service.

      8.13 Focal will furnish to Ameritech all information necessary for
provision of OS and DA. This information, to the extent it is identified as
such, shall be treated as Proprietary



                             Sch. 9.5 - 16
<PAGE>
 
Information. For OS this information includes emergency agency phone numbers,
rate information (such as mileage bands and operator surcharge information), and
originating screening information.  Focal will furnish to Ameritech all
information necessary for the provision of OS and DA.

            8.13.1  To the extent that Focal does not mirror Ameritech's
      operator surcharge rates, then Ameritech will, if technically feasible,
      enter Focal's surcharge rates into Ameritech's rate tables, and will
      charge Focal for changing those tables at the rates then charged by
      Ameritech for such service.

            8.13.2  For DA services, Focal will furnish Ameritech ninety (90)
     days (or such earlier time as the Parties may agree upon) before DA service
     is initiated details necessary ID to provide that service. This information
     includes listing information for the areas to be served by Ameritech and
     network information necessary to provide for the direct trunking of the DA
     calls.

            8.13.3  Focal will keep these records current and will inform
     Ameritech, in writing, at least thirty (30) days prior to any changes in
     the format to be made in such records. Focal will inform Ameritech of other
     changes in the records on a mutually agreed-upon schedule.
                    
     8.14   Upon request, and as technically feasible, Ameritech will re-brand
such OS and DA services based upon Focal's obtaining or providing any required
facilities, services, Network Elements and custom routing, and their agreement
to pay rates that compensate Ameritech for any costs it incurs in developing,
installing, providing and maintaining such rebranded service. For branding of
calls, Focal must provide two (2) cassette tapes of an announcement, no longer
than three (3) seconds, for installation on each OS and DA switch serving
Focal's Customers.

     8.15   Branding: Re-branding is available as follows:
            --------

                (a) Mechanized front-end branding is available for all manual
            and automated OS calls.

                (b) Mechanized back-end branding is available for automated
            calling card calls handled via ACCS.

                (c) On mechanized collect and billed-to-third calls, back-end
            branding is not currently available.

                (1) Such calls can be manually handled and branded.

                (2) If Customer desires mechanized branding, the feature can be
                    installed if Focal pays for feature purchase and
                    installation.

     Normally, OS and DA services, both bundled and unbundled, will be branded
     with Ameritech's name as the provider of the service. Upon request from
     Focal, and as technically

                             Sch. 9.5 - 17
<PAGE>
 
feasible, Ameritech will re-brand OS and DA traffic from Focal's telephone
exchange lines, or to Focal's unbundled OS or DA network element. Re-Network
Element. Re-branded service requires that Focal arrange to have the subject OS
or DA traffic delivered to Ameritech's Central Office on separate trunks, which
may require that it obtain custom routing, and obtain or provide such trunks and
other applicable.

      Re-branding is provided at rates that recover Ameritech's costs of
developing, installing, providing and maintaining such service. 

      8.16  Focal grants to Ameritech during the term of this Agreement a non-
exclusive license to use the DA listings provided pursuant to this Agreement. DA
listings provided to Ameritech by Focal under this Agreement will be maintained
by Ameritech only for providing DA information, and will not be disclosed to
third parties. This section does not prohibit Ameritech and Focal from entering
into a separate agreement which would allow Ameritech to provide or sell Focal's
DA listing information to third parties, but such provision or sale would only
occur under the terms and conditions of the separate agreement.

      8.17  Ameritech will supply Focal with call detail information so that
Focal can rate and bill the call. This information excludes rating and invoicing
of Customers, unless negotiated on an individual case basis.

                             Sch. 9.5 - 18
<PAGE>
 
                                 SCHEDULE 9.10

                    NETWORK ELEMENT PERFORMANCE ACTIVITIES


A.  Non-DS1 Loops-Standard Intervals
    Volume*                                  Interval         
    -------                                  --------        
     1-24                                    5 Business Days 
    25-48                                    6 Bus!ness Days 
    49-96                                    7 Business Days
    97+                                      Negotiated       
                          *Number of Loops Per Order Per Day

B.  DS1 Unbundled Local Transport

    1.   Facilities Available                7 Business Days

    2.   Force and Load                      Negotiated Interval 
         Not Available

C.  DS3-Unbundled Local Transport            Negotiated Interval

D.  OC-N-Unbundled Local Transport           Negotiated Interval

                             Sch. 9.10 - 1
<PAGE>
 
                                 SCHEDULE 10.1

                           WHOLESALE RESALE SERVICES

The Resale Services provided hereunder by Ameritech are those Telecommunications
Services set forth in the Resale Tariff(s). The rates for such Resale Services
are set forth in the Resale Tariff(s).

                                Sch. 10.1 - 1
<PAGE>
 
                                SCHEDULE 10.3.1
                 GRANDFATHERED SERVICES AND SUNSETTED SERVICES
                                   MICHIGAN
                                        
                             TARIFF MPSC NO. 20 R
<TABLE> 
<CAPTION>
<S>                                                      <C>                         <C> 
  TOPIC                                                  SECTION                     SHEET
  Automatic Voice Connecting Arrangements                    8                         4   
                                                                          
  Budget Toll Dialing Service                                9                        15   
                                                             
  Centrex - DS (Digital)                                     5                        38  
                                                                          
  Centrex IV                                                 5                         5 
                                                                          
  Centrex V                                                  5                        22  

  Channels for Key Telephone Systems                         8                         3

  Channels for Television Transmission for Use in           18                        17              
  Educational Television Systems              

  Channels for Television Transmission - Other Than for     18                         1              
  Use in Educational Television Systems                                 
                                                                          
  Circle Calling 30                                          9                        13
                                                            
  Circle Calling Service                                     9                        16
                                             
  Cross Boundary Rate Treatment for Direct High             15                         1
  Capacity Service                                                     
 
  Entrance Facilities                                       15                        90

  Equipment and Miscellaneous Charges (Private Line)        15                       134
                                                                           
  Foreign Telephone Service                                  4                         3             
  
  High Capacity Services                                    15                       144               
  
  Interexchange (Interzone) Channel Charges                 15                        92             
  
  Intraexchange (Intrazone) Channel Charges                 15                       114
  
  Local Distribution Channel                                15                         4           

  Municipal Emergency Reporting Service                      8                         1            
                                                                       
  Premiere Service                                           6                         1
                       
  Premiere 2/6 Service                                       6                         3
 
  Registered Equipment and Circuits (Private Line)          15                        65
  
  Rotary Business Service                                    4                         8
  
  Rotary Residence Service                                   4                         8
</TABLE> 
                                Sch. 10.3.1 - 1
                      
<PAGE>
 
<TABLE> 
<CAPTION> 
<S>                                                       <C>                             <C> 
TOPIC                                                     SECTION                         SHEET
Services Involved in Exchange Boundary Revisions            4                              1    

Special Protection Equipment                               15                              5

Subvoice Channel Services                                  15                              6

Universal Emergency Number Service (911)                    8                              2

Value Calling Plan                                          9                              4

Value Plus Contract Service                                 9                              1

Wideband Metallic Channel                                  15                              7
</TABLE> 


                               Sch. 10.3.1 - 2
<PAGE>
 
                                SCHEDULE 10.3.1

                GRANDFATHERED SERVICES AND SUNSETTED SERVICES            
                                   MICHIGAN                    
               
                                     OTHER

         TOPIC

         Apartment Door Answering Service

         Automatic Identified Outward Dialing (AIOD) Service 

         Automatic Intercept Service (A.I.S.)

         Automatic Voice Connecting Arrangements
         
         Business Interphone Service

         Centrex CO Systems - ESS

         Centrex CO Systems - No. 5X-BAR

         Centrex - DS

         Centrex - General

         Centrex IV

         Centrex V

         Centrex Mate

         Centrex Message Desk Interface

         Centrex - Special Features

         Centrex Station Call Through Test

         Concentrator-Identifier - Four Trunk Capacity

         Home Interphone Service

         Intercom Calling

         Lobby Interphone Service

         Semi-Public Telephone Service

         Time-of-Day Announcement Service

         Two-Way Intercommunications Arrangement

                               Sch. 10.3.1 - 3 
<PAGE>
 
         TOPIC
 
         Value Calling Plan (Sunsetted)
 
         Voice Calling Service
 
         WATS
                                
                               Sch. 10.3.1 - 4
 
<PAGE>
 
                            SCHEDULE 10.9.2

                        RESALE PERFORMANCE BENCH-MARKS

A.  Installation

    1.    Installation Intervals

          a.  POTS

              (1) Percentage Installed on Time

              (2) Installation Interval More Than Six (6) Days

          b.  HICAP: Percentage of Missed Appointments

SUBRATE: Percentage of Missed Appointments

    2.    New Service Failures

          a. POTS:      Percentage of New Service Failures During First Seven
                        (7) Days from Installation Date

          b. HICAP:     Percentage of New Service Failures During First Thirty
                        (30) Days from Installation Date
 
          c. SUBRATE:   Percentage of New Service Failures During First Thirty
                        (30) Days from Installation Date 

B.  Repair
 
    1.    Time to Repair
 
          a. POTS:      Percentage of Repairs Not Completed within twenty-four
                        (24) hours

          b. HICAP:     Percentage of Repairs Not Completed within two (2) hours

          c. SUBRATE:   Percentage of Repairs Not Completed within three and 
                        one-half (3 1/2) hours

    2.    Percentage of Initial Trouble Reports

    3.    Percentage of Code 4 Troubles

C.  Time to Provide Firm Order Commitment

    1.    Switched Services: Percentage of Firm Order Commitments Provided in
          four (4) days of Date of Order

    2.    HICAP Services: Percentage of Firm Order Commitments Provided
          within twenty-four (24) hours of Time of Order

                              Sch. 10.9.2 - 1
<PAGE>
 
D.  Speed of Answer

    1.    Service Center: Percentage of Calls to Service Center made during
          normal business hours that are answered within ten (10) seconds

    2.    Repair Center: Percentage of Calls to Repair Center that are answered
          within twenty (20) seconds.

    3.    Operator Services: Toll Assistance Speed of answer (seconds).
         
    4.    Operator Services: Directory Assistance Speed of answer (seconds). 

                                Sch. 10.9.2 - 2
<PAGE>
 
                                SCHEDULE 10.9.6

                               CREDIT ALLOWANCES
                                   MICHIGAN
                                        
1.   In the event of an interruption to the service provided pursuant to any of
     Sections 3.8, 9.10 or 10.9 by a Party (the "Providing Party") to the other 
     ------------  ----    ----
     Party (the "Receiving Party") which is not due to the negligence or willful
     act of Receiving Party or its Customer, upon notice and application by
     Receiving Party an allowance will be made for the time interruption
     continues.

2.   The liability of Providing Party for any credit allowance arising out of
     mistakes, omissions, interruptions, delays, errors or defects in
     transmission, or failures or defects in facilities furnished by the
     Providing Party, occurring in the course of furnishing service or other
     facilities and not caused by the negligence of Receiving Party or of
     Providing Party in failing to maintain proper standards of maintenance and
     operation and to exercise reasonable supervision shall in no event exceed
     an amount equivalent to the proportionate charge to Receiving Party for the
     period of service during which such mistake, omission, interruption,delay
     or error or defect in transmission or failure or defect in facilities
     occurs.

     The services furnished by Providing Party, in addition to the limitation
     set forth preceding, also are subject to the following limitation:
     Providing Party shall not be liable for any credit allowance arising out of
     mistakes, omissions, delays, errors or defects in transmission or other
     injury, including injuries to persons or property from voltages or currents
     transmitted over the service of Providing Party (a) caused by Receiving
     Party or Receiving Party Customer-provided equipment (except where a
     contributing cause is the malfunctioning of a Providing Party connecting
     arrangement, in which event the liability of the Providing Party shall not
     exceed an amount equal to a proportional amount of Providing Party billing
     for the period of service during which such mistake, omission,
     interruption, delay, error, defect in transmission or injury occurs), or
     (b) not prevented by Receiving Party or Receiving Party Customer-provided
     equipment but which would have been prevented had Providing Party-provided
     equipment been used.

3.   When the lines of other telecommunication providers or facilities of other
     persons are used in establishing connections to points not reached by the
     Providing Party's lines, the Providing Party is not liable for any act or
     omission of the other provider or persons.

                               Sch. 10.9.6 - 1
<PAGE>
 
                               SCHEDULE 10.11.1

                   FORM OF REPRESENTATION OF AUTHORIZATION

    Focal hereby represents to Ameritech, for purposes of obtaining a Customer's
Customer Proprietary Network information ("CPNI") or for placing an order to
change or establish a Customer's service, that it is a duly certificated LEC and
that it is authorized to obtain CPNI and to place orders for Telephone Exchange
Service (including Resale Service) upon the terms and conditions contained
herein.

1.  With respect to requests for CPNI regarding prospective Customers of Focal,
    Focal acknowledges that it must obtain written or electronic authorization
    in the form of a signed letter, tape-recorded conversation, password
    verification, or other means ("DOCUMENTATION OF AUTHORIZATION") which
    explicitly authorizes Focal to have access to the prospective Customer's
    CPNI. The Documentation of Authorization must be made by the prospective
    Customer or the prospective Customer's authorized representative. In order
    to obtain the CPNI of the prospective Customer, Focal must submit to
    Ameritech the Documentation of Authorization. If Focal cannot provide
    applicable Documentation of Authorization, then Ameritech shall not provide
    CPNI to Focal.

2.  If Focal has already obtained Documentation of Authorization for the
    Customer to place an order for Telephone Exchange Service for the Customer,
    Focal need not submit Documentation of Authorization to obtain the
    Customer's CPNI.

3.  With respect to placing a service order for Telephone Exchange Service
    (including Resale Services) for a Customer, Focal acknowledges that it must
    obtain Documentation of Authorization which explicitly authorizes Focal to
    provide Telephone Exchange Service to such Customer. The Documentation of
    Authorization must be made by the prospective Customer or Customer's
    authorized representative. Focal need not submit the Documentation of
    Authorization to process a service order. However, Focal hereby represents
    that it will not submit a service order to Ameritech unless it has obtained
    appropriate Documentation of Authorization from the prospective Customer and
    has such Documentation of Authorization in its possession.

4.  The Documentation of Authorization must clearly and accurately identify
    Focal and the prospective Customer.

5.  Focal shall retain all Documentation of Authorization in its files for as
    long, as Focal provides Telephone Exchange Service to the Customer, or for
    as long as Focal makes requests for information on behalf of the Customer.

6.  Focal shall make Documentation of Authorization available for inspection by
    Ameritech during normal business hours. In addition, Focal shall provide
    Documentation of Authorization for Customers or prospective Customers to
    Ameritech upon request.

6282481.4

                             Sch. 10. 11. 1 - I
<PAGE>
 
7.   Focal is responsible for, and shall hold Ameritech harmless from, any and
     all Losses (as defined in that certain Interconnection Agreement under
     Sections 251 and 252 of the Telecommunications Act of 1996 dated as of
     January 29, 1997 by and between Ameritech Information Industry Services, a
     division of Ameritech Services, Inc. on behalf of and as agent for
     Ameritech Michigan and Focal Communications Corporation of Michigan, (the
     "INTERCONNECTION AGREEMENT") resulting from Ameritech's reliance upon
     Focal's representations as to its authority to act on behalf of a Customer
     or prospective Customer in obtaining CPNI or placing a service order for
     Telephone Exchange Service.

8.   If Focal falls to repeatedly and materially abide by the procedures set
     forth herein, Ameritech reserves the right to insist upon the submission of
     Documentation of Authorization for each Customer in connection with a
     request for a service order.

9.   This Representation of Authorization shall commence on the date noted below
     and shall continue in effect until the termination or expiration of the
     Interconnection Agreement.

     Dated this _______ day of _____ 199.

FOCAL COMMUNICATIONS CORPORATION OF MICHIGAN

By:_______________________________
Title:____________________________
Printed Name:_____________________

                               Sch. 10.11.1 - 2
<PAGE>
 
                            SCHEDULE 10.12.6

                     LAW ENFORCEMENT INTERFACES

1.0  INTRODUCTION.

     Consistent with Applicable Law, it is necessary for Focal and Ameritech to
provide interface requirements to allow Focal to use a standard set of
procedures for meeting the requirements of applicable law enforcement agencies
("LAW ENFORCEMENT PROCESS"). The Law Enforcement Process will enable Focal to
provide identical services to its Customers. These services include Annoyance
Call Bureau, wire intercept, wire trap, wire trace, fraud control, physical
security and subpoena management.

2.0  LAW ENFORCEMENT.

    Definition - The Law Enforcement Process assures that Focal (as a reseller
of Resale Services) is in total compliance with law enforcement requirements
related to providing local Services to its Customers. Ameritech (switch owner
or access provider) agrees to support law enforcement requirements as provided
by the CALEA.

3.0  ANNOYANCE CALL BUREAU.

     3.1  Definition - Ameritech Annoyance Call Bureau (AACB) conducts
investigations to help determine who the unwanted callers are after victims
receive annoying calls and files an official complaint with the local law
enforcement agency. Annoying calls are: threatening, harassing, obscene, prank,
hang-ups, unwanted sales pitches, and survey calls. The information obtained
will only be released to the local law enforcement agency.

                       
     3.2  When Focal must initiate a wire trap or trace as a result of its
customer receiving an annoying call (e.g., threatening, harassing, obscene,
                                     ----
prank, hang-ups, unwanted sales pitches, and survey calls), the following
operational interfaces should occur:

          3.2.1.   Focal (the reseller) shall inform its Customer that they must
     file a formal complaint with the local police department and obtain
     agency's name, officer's name and case or report number.

          3.2.2.   Focal shall contact Ameritech Annoyance Call Bureau on behalf
     of its Customer and provide the required information to initiate trap or
     call trace.

          3.2.3    The AACB shall conduct investigations to determine who the
     unwanted caller is, work with local police departments to gather evidence:
     and even testify in court on behalf of Focal Customers who have received
     annoying calls. AACB will build case for and establish trap for twenty-one
     (21) days. Focal shall contact the AACB (21) days. Focal shall contact the
     AACB to renew the trap beyond twenty-one (21) days. 

                             Sch. 10.12.6 - 1
<PAGE>
 
          3.2.4. The AACB shall provide to Focal a toll free number which will
     be accessible daily Monday through Friday from 8:00 a.m. - 5:00 p.m.

          3.2.5. For non-emergency (not life threatening) situations, Focal
     shall advise its Customer to contact its local Law Enforcement Agency and
     to provide Focal with required information to initiate a trap or call
     trace. Focal will contact AACB during standard operating hours to establish
     a case. For emergency (life threatening) situations, Focal shall inform its
     Customer to contact its local Law Enforcement Agency and this Agency will
     contact Ameritech to initiate a trap or call trace.

          3.2.6. Additionally, for emergency situations, Ameritech corporate
     security will provide Focal representatives with an emergency security
     contact number.

          3.2.7. Focal's Customer must contact Focal with the dates and times of
     the unwanted calls. Focal shall fax the dates and times of the unwanted
     calls to the Annoyance Call Bureau.

          3.2.8. At the end of the tracing investigation (twenty-one (21)-day
     period), Ameritech Annoyance Call Bureau shall send written confirmation to
     Focal informing Focal of the disposition of the case (i.e., successful or
                                                           ---- 
     non-successful). All evidence obtained on a successful case will be 
     forwarded to the local law enforcement agency that Focal provided to the 
     AACB. Focal shall inform its Customer of the results of the investigation.
      
          3.2.9. If Focal Customers call Ameritech to initiate an annoying call
     report, report, Ameritech shall advise the person receiving the annoying or
     harassing to call Focal.     

4.0  WIRE INTERCEPT.

     4.1. Definition - Requests from law enforcement agencies to conduct a form
of electronic or mechanical eavesdropping where, upon court order, law
enforcement officials surreptitiously monitor phone calls (e.g. conversations or
                                                           ----
data) of Focal Customers.

     4.2. Operational Interface Requirements - The Law Enforcement Agency local
police department or government organization) shall serve Ameritech with a court
order, authorizing Ameritech to conduct a wire intercept on the Focal Customer
line.

5.0  PEN REGISTER (DIAL NUMBER RECORDER).

     5.1. Definition - Requests from law enforcement agencies to conduct a
"form" of identifying calls dialed by Focal Customers in local Exchange Areas. A
pen register is a mechanical device that records the numbers dialed or pulsed on
a telephone by monitoring the electrical impulses caused when the dial on the
telephone is released. A pen register does not overhear oral communications and
does not indicate whether calls are actually completed; thus, there is no
recording or monitoring of the conversations.

                             Sch. 10.12.6 - 2
<PAGE>
 
     5.2. Operational Interface Requirements - See Wire Intercept Section 4.1.

6.0 TRACE.

     6.1. Definition - A form of electronic identification of calling numbers,
where, upon consent from the Focal Customer (via Focal) or court order, law
enforcement officials request a record of calling numbers to the premises of the
Focal Customer.

     6.2. Central Office Features - Call Trace is an advanced custom calling
feature which provides Focal direct line Customers the ability to activate the
feature by dialing a designated code. This will automatically trace the
telephone number of the line used for the last call received by the Customer.
The traced number will not be provided to the Customer, but will be provided to
law enforcement officials.

7.0  SUBPOENA MANAGEMENT.

     7.1. Definition - The law enforcement process initiated to compel the
production of certain specific documents (e.g., Customer information, name,
                                          ----
address, service type, call usage records, etc.) relevant to a legal proceeding,
are made and make them readily retrievable by local police departments,
government organizations, and attorneys. Other legal demands require the
capability to honor other legal process demands (e.g., establishment of dialed
                                                 ---- 
number recorders, wire intercepts, & trace services, etc.)

     7.2. Operational Interface Requirements - The law enforcement agency (e.g.,
                                                                           ----
local police department, government organization, or attorney) shall serve
Ameritech an original subpoena naming Ameritech in its court document for
requests for Customer information (see above definition). Ameritech shall
forward call trace information to the law enforcement agency for inquiries
regarding Focal Customers. If the law enforcement agency serves Focal the
original subpoena, Focal shall forward a copy of the original subpoena to
Ameritech and advise the law enforcement agency to re-send an original subpoena
naming Ameritech in its court document. Ameritech shall notify Focal of the
resolution of the investigation. However, Ameritech shall only provide the
results of the investigation to the proper law enforcement agency.
                      
     7.3. Operations Interface Requirements for calls originating from a long
distance carrier, computer, fax machine, pay phones, and telemarketing calls to
Focal's Customers are pending further discussions with Ameritech.

                             Sch. 10.12.6 - 3
<PAGE>
 
                                SCHEDULE 10.13

                         RESALE MAINTENANCE PROCEDURES

     By the end of Contract Month 1, /23/ the Implementation Team shall agree
                                      --
upon the processes to be used by the Parties for maintenance of Resale Services.
These processes will address the implementation of the requirements of this
SCHEDULE 10.13.
--------------

     1.   Ameritech shall provide repair, maintenance, and testing, for all
Resale Services in accordance with the terms and conditions of this SCHEDULE
                                                                    --------
10.13.
-----

     2.   Ameritech technicians shall provide repair service that is at least
equal in quality to that provided to Ameritech Customers; trouble calls from
Focal Customers shall receive response time priority that is at parity to that
of Ameritech Customers and shall be based on trouble severity, regardless of
whether the Customer is an Focal Customer or an Ameritech Customer.

     3.   Ameritech shall provide Focal with the same scheduled and non-
scheduled maintenance, including required and recommended maintenance intervals
and procedures, for all Resale Services provided to Focal under this Schedule
that it currently provides for the maintenance of its own network. Ameritech
shall provide Focal notice of any scheduled maintenance activity which may
impact Focal's Customers on the same basis it provides such notice to its
subsidiaries, Affiliates, other resellers and its retail Customers. Scheduled
maintenance shall include such activities as switch software retrofits, power
tests, major equipment replacements, and cable rolls.

     4.   Ameritech shall provide notice of non-scheduled maintenance activity
that may impact Focal Customers. Ameritech shall provide maintenance as promptly
as possible to maintain or restore service and shall advise Focal promptly of
any such actions it takes.

     5.   If service is provided to Focal Customers before an EI is established
between Focal and Ameritech, Focal will transmit repair calls to Ameritech
repair bureau by telephone.

     6.   Ameritech repair bureau, including the EI to be established pursuant
to the Implementation Plan, shall be on-line and operational twenty-four (24)
hours per day, seven (7) days per week except when preventative maintenance and
software revisions require an out-of-service condition. Ameritech will provide
Focal a twenty-four (24) hour advanced notification of such out-of-service
conditions.



__________________________

/23/   Since the terms of this Agreement are the result of Focal's adoption
 --
       under Section 252(i) of the Act of the AT&T Agreement, the Parties agree
       that the term "Contract Month 1", for purposes of this SCHEDULE 10.13,
                                                              --------------
       shall expire on February 28, 1999.

                              Sch. 10.13 - 1
<PAGE>
 
     7.   Ameritech shall provide progress reports and status-of-repair efforts
to Focal upon request, and at a frequency interval to be determined by Focal.
Ameritech shall inform Focal of restoration of Resale Service after an outage
has occurred.

     8.   Maintenance charges for premises visits by Ameritech technicians shall
be billed by Focal to its Customer, and not by Ameritech. The Ameritech
technician shall, however, present the Customer with unbranded form detailing
the time spent, the materials used, and an indication that the trouble has
either been resolved or that additional work will be necessary, in which case
the Ameritech technician shall make an additional appointment with the Customer.
The Ameritech technician shall obtain the Customer's signature when available
upon said form, and then use the signed form to input maintenance charges into
Ameritech's repair and maintenance database.

     9.   Dispatching of Ameritech technicians to Focal Customer premises shall
be accomplished by Ameritech pursuant to a request received from Focal. The EI
established between the Parties shall have the capability of allowing Focal to
receive trouble reports, analyze and sectionalize the trouble, determine whether
it is necessary to dispatch a service technician to the Customer's premises, and
verify any actual work completed on the Customer's premises.

Critical or Expedited Troubles.
-------------------------------

     Upon receiving a referred trouble from Focal, the Ameritech technician will
offer a dispatch appointment and quoted repair time dependent upon Ameritech's
force-to-load condition. Ameritech's maintenance administrators will override
this standard procedure on a non-discriminatory basis, using the same criteria
as Ameritech uses to expedite intervals for itself and its subsidiaries,
Affiliates and retail Customers. If Ameritech will be unable to meet an Focal
expedited request, Ameritech will notify Focal and Focal will have the option to
implement the escalation process described in the Implementation Plan.





                              Sch. 10.13 - 2
<PAGE>
 
Disaster Recovery

The Implementation Plan will establish a process for disaster recovery that
addresses the following:

Events affecting Ameritech's network, work centers and operational support
systems;

Establishing and maintaining a single point of contact responsible for disaster
recovery activation, statusing and problem resolution during the course of a
disaster and restoration;

Procedures for notifying Focal of problems, initiating restoration plans and
advising Focal of the status of resolution;

Definition of a disaster; and

Equal priority, as between Focal Customers and Ameritech Customers, for
restoration efforts, consistent with FCC Service Restoration guidelines,
including, without limitation, deployment of repair personnel, and access to
spare parts and components.

                              Sch. 10.13 - 3
<PAGE>
 
                               SCHEDULE 10.13.2

           SERVICE ORDERING AND PROVISIONING INTERFACE FUNCTIONALITY

Electronic interfaces will provide Focal with the ability to:

     a)   Obtain, during sales discussions with a Customer, access to the
          following Ameritech Customer service record data in a manner which is
          transparent to the Customer:

          .   Billing, telephone number/name/address
          .   Service Location Address
          .   Working telephone number(s) on the account
          .   Existing service and features
          .   Blocking
          .   CLASS Features
          .   Telephone Assistance Programs, Telephone Relay Service and similar
              services indicator 
          .   Special Exemption Status indicator
          .   Directory Listing Information
          .   Information necessary to identify the IntraLATA toll provider and
              InterLATA provider, as applicable.

     b)   Obtain information on all features and services available;

     c)   Enter the Focal Customer order for all desired features and services;

     d)   Assign a telephone number (if the Focal Customer does not have one
          assigned);

     e)   Establish the appropriate directory listing;

     f)   Determine if a service call is needed to install the line or service;

     g)   Schedule dispatch and installation, if applicable;

     h)   Provide installation dates to Customer;

     i)   Order local intraLATA toll service and enter Focal Customer's choice
          of primary interexchange carrier on a single, unified order; and

     J)   Suspend, terminate or restore service to an Focal Customer.

Ameritech will support four (4) transaction types; Assume; Change; New; and
Delete, as described in Ameritech's Electronic Service Guide, which is based on
TCIF Customer Service, Issue 5.



                             Sch. 10.13.2 - 1
<PAGE>
 
Notwithstanding the foregoing, Focal shall be entitled to place orders to
transfer a Customer to Focal without identifying the specific features and
services being subscribed by such Customer at the time of the request 
("MIGRATION-AS-IS"). Furthermore, if a Customer requests changes to its features
and/or such service at the time of transfer, as part of a request for Migration-
As-Is, Focal need only specify the features and/or services which are to change.
However, unless agreed to by Ameritech, Migration-As-Is will not include any
service subscribed which is not a Telecommunications Service.
 
Critical or expedited orders:

Focal may request that the standard interval for provisioning will be expedited
if Ameritech's standard intervals do not meet the Focal Customer's requested due
date. Orders will be expedited by Ameritech on the same basis as it expedites
orders for itself and its subsidiaries, Affiliates and retail Customers. If
Ameritech will be unable to meet an Focal expedite request, Ameritech will
notify Focal and Focal shall have the option to implement the escalation process
to be defined in the Implementation Plan.





                               Sch. 10.13.2 - 2
<PAGE>
 
                                SCHEDULE 12.9.1

                    PHYSICAL COLLOCATION SPACE RESERVATION

     Space for Physical Collocation may be reserved on the following basis:

     1.   Focal may reserve additional space in an Ameritech Central Office in
which it has (or is ordering) for Physical Collocation for permitted
telecommunications-related equipment.

     2.   A reservation may be maintained only by the payment of a non-recurring
charge to defray the administrative costs of the reservation system
("RESERVATION CHARGE").
    
    3.    The reservation can be made for an amount of space no greater than the
amount of active Physical Collocation space being utilized (or ordered) for
Interconnection with and/or access to the Network Elements of Ameritech by Focal
in the particular Central Office.

    4.    The reservation takes a priority based on the time at which it is
made.

    5.    In the case of an order for Physical Collocation in an office in which
all the unoccupied space is covered by reservations, all reservations will be
prioritized. The holder(s) of the lowest priority reservation(s) which, when
considering all higher priority reservations, still represent(s) available space
sufficient to fill the order for Physical Collocation ("OPTION PARTY") will be
given the option of "enforcing" or relinquishing its (their) reservation(s).

          In this case, an Option Party may enforce its reservation by payment
of the recurring Physical Collocation floor space charge otherwise applicable to
the reservation space (in lieu of the nonrecurring Reservation Charge). The
reservation will be maintained until the Physical Collocation arrangement in
that office is terminated or the reservation is terminated, whichever comes
first. A new reservation may be activated by payment of the Reservation Charge,
but it will take a new priority based on the time of reactivation. If an Option
Party decides to enforce its reservation in this manner, the holder(s) of the
reservation(s) with the next higher priority will be given the option of
enforcing or relinquishing its (their) reservation(s).

    If an Option Party declines to enforce its reservation as indicated above,
the reservation is relinquished. A new reservation may be activated by payment
of the Reservation Charge, but it will take a new priority based on the time of
reactivation.

     6.   The holder of a valid reservation may place an order for Physical
Collocation for the reserved space at any time. If there is sufficient
unoccupied space to accommodate the order after subtracting space covered by
reservations of higher priority, the order will be processed. If there is
insufficient space to accommodate the order after subtracting space covered by
reservations of higher priority and which have been enforced, the holder may
maintain its reservation as set forth in Section 5 above.

                              Sch. 12.9.1 - 1
<PAGE>
 
    7.  In a Central Office, Ameritech may reserve space on the following
        conditions.
    
    .   The amount of space must be the least amount of space reasonably
        necessary for the provision of a communications-related service --
        including Interconnection and the provision of unbundled Network
        Elements. Except for space reserved for switch (including Tandem
        Switches and STPs) conversion and growth and for augmentation and
        conversion of mechanical and electrical support systems and building
        infrastructure, the reserved space must reasonably be anticipated to be
        used in three (3) years.
    
    .   The total amount of space reserved cannot exceed the amount of space
        Ameritech is currently using in the Central Office.
    
    .   Ameritech will impute an amount equal to the reservation charge to the
        appropriate operations for which the space is reserved.

    8.  Ameritech shall enforce its reservation in the same manner in which
Focal and other collocating Telecommunicating Carriers shall be required to
enforce its reservations. In that case, Ameritech will impute the floor space
charge to the operations for which the space is reserved.

                                Sch. 12.9.1 - 2
<PAGE>
 
                                SCHEDULE 12.9.3

                         COLLOCATION CAPACITY PLANNING

    By the end of Contract Month 3, /24/ Focal and Ameritech shall jointly
                                     --
develop a planning process for meeting Focal's space and intraoffice facility
requirements which shall include the procedures to be followed for the Focal
quarterly forecast of anticipated additional power requirements.


__________________

/24/  Since the terms of this Agreement are the result of Focal's adoption under
 --                                                                            
      Section 252(i) of the Act of the AT&T Agreement, the Parties agree that
      the term "Contract Month 3", for purposes of this SCHEDULE 12.9.3, shall
                                                        ---------------
      expire on April 30, 1999.

                                Sch. 12.9.3 - 1
<PAGE>
 
                                SCHEDULE 12.12

                         DELIVERY OF COLLOCATED SPACE

1.0 DELIVERY OF PHYSICAL COLLOCATION SPACE

    1.1 Upon receiving the written notification of the availability of
Collocation space from Ameritech, Focal shall send written verification that it
still requires each Collocation space requested on Focal's application for which
space is available. This written notification is Focal's firm order for service
for each Collocation space requested. Subject to SECTION 1.3 below, Focal's
                                                 -----------               
written notification shall be accompanied by Focal's payment of forty percent
(40%) of all applicable Central Office Build Out ("COBO") fees (the "INITIAL
COBO PAYMENT"). COBO modifications and additions to space described in the
proposal will not begin until the Initial COBO Payment has been paid. Delayed
payment of the Initial COBO Payment may delay the actual service date.

    1.2 So long as Focal has a satisfactory credit rating with Ameritech for the
twelve (12) month period preceding the date of Focal's request for Collocation
pursuant to SECTION 12.12, Focal shall pay the COBO charges as follows:
            -------------

    Initial COBO Payment:                              40% of COBO charges 
                                                  
    Delivery by Ameritech of confirmation         
    that construction of space is fifty percent   
    (50%) complete:                                    40% of COBO charges 
                                                  
    Completion of space conditioning:                  20% of COBO charges 

If Focal's credit rating is not satisfactory within the aforementioned period,
Focal shall pay the COBO charges in accordance with the provisions of
Ameritech's applicable tariff.

    1.3 If Focal's credit rating is not satisfactory within the aforementioned
period, Focal shall pay the COBO charges in accordance with the provisions of
Ameritech's applicable tariff.

2.0 ADDITIONAL RULES AND REGULATIONS APPLICABLE TO PHYSICAL COLLOCATION SPACE

    Physical Collocation will be provided subject to the following provisions:

    2.1 Focal will be responsible for any extraordinary costs incurred by
Ameritech to prepare the Collocation space for the installation of Focal's
equipment and for extraordinary costs to maintain the Collocation space for
Focal's equipment on a going-forward basis. Extraordinary costs may include
costs for such items as asbestos removal, fire suppression system or
containment, modifications or expansion of cable entry facility, increasing the
DC power system infrastructure capacity, increasing the capacity of the standby
AC system or the existing commercial power facility, conversion of
non-Collocation space, compliance with federal and state requirements or other
modifications required by local ordinances. Ameritech will charge for these
costs on a time-sensitive or time-and-materials basis.

                                Sch. 12.12 - 1
<PAGE>
 
An estimate of such costs plus contribution will be provided to Focal prior to
commencing such work. Extraordinary costs will only be billed to Focal if such
costs have been authorized by Focal. Ameritech must advise Focal if
extraordinary costs will be incurred within ten (10) Business Days from the
initial walkthrough. Otherwise, Focal will not be responsible for such costs.
Extraordinary costs do not include costs associated with maintenance and upkeep
of the building.

    At the initial walkthrough referred to in SECTION 12.12.2(b), Ameritech
                                              ------------------
shall provide to Focal a written proposal which covers Focal's requirements for
the space and details the associated requirements and the applicable charges
required to meet Focal's specific request and the expected service date. Focal
shall acknowledge acceptance of the charges in the written proposal by signing
it and returning a copy to Ameritech. Upon receipt of Focal's signed proposal,
Ameritech will begin the work and charge Focal for the actual time and material
needed to complete the modifications plus a reasonable contribution. In no case
will actual charges exceed those estimated by more than ten percent (10%).

    2.2 Focal will be responsible for notifying Ameritech of any significant
outages of Focal's equipment which could impact any of the services offered by
Ameritech, and provide estimated clearing time for restoration.

    2.3 Focal is responsible for coordinating with Ameritech to ensure that
services are installed in accordance with the service request.

    2.4 Focal is responsible for testing, if necessary, with Ameritech to
identify and clear a trouble when the trouble has been sectionalized (isolated)
to an Focal-provided service.

    2.5 Before beginning delivery, installation, replacement or removal work
for equipment and/or facilities located within the Collocation space, Focal
shall obtain Ameritech's written approval of Focal's proposed scheduling of the
work in order to coordinate use of temporary staging areas and other building
facilities. Ameritech may request additional information before granting
approval and may require scheduling changes. Focal must submit written plans for
equipment to be installed in the Collocation space prior to commencing
installation.

    2.6 Ameritech has the right to inspect Focal's completed installation of
equipment and facilities and to make subsequent and periodic inspections of the
customer's equipment and facilities occupying a Collocation space and associated
entrance conduit and riser space. If Focal is found to be in non-compliance with
the terms and conditions of this Schedule, Focal must modify its installation
to achieve compliance. Ameritech will notify Focal in advance of such
inspections, and Focal shall have the right to be present at the time of the
inspection.

3.0 DELIVERY OF VIRTUAL COLLOCATION SPACE

    3.1 Ameritech shall allow periodic inspections of Virtual Collocation space
where Focal equipment is located.

                                Sch. 12.12 - 2
<PAGE>
 
     3.2 Ameritech shall ensure that all applicable alarm systems (e.g., power)
                                                                   ----
that support Focal equipment are operational and the supporting databases are
accurate so that equipment that is in alarm will be properly identified.

     3.3 See Tariff F.C.C. No. 2, Section 16.3.

                                Sch. 12.12 - 3
<PAGE>
 
                                SCHEDULE 12.15

                              COMMON REQUIREMENTS

     The following requirements are applicable to both Physical and Virtual 
Collocation:

     1.   Ameritech shall provide to Focal any intraoffice facilities that Focal
requests and that Ameritech provides by tariff or contract to any carrier.

     2.   Ameritech shall allow for a Fiber Meet arrangement between the 
Parties' networks and facilities at the DS0, DS1, DS3, OC3, OC12 and OC48 rates 
pursuant to mutual agreement of the Parties.

     3.   Focal may provide basic telephone service with a connection jack for 
the Collocated space.

     4.   Ameritech shall provide adequate lighting, ventilation, power, heat, 
air conditioning, and other environmental conditions for Focal's space and 
equipment. These environmental conditions shall comply with Bellcore Network 
Equipment-Building System (NEBS) standards TR-EOP-000063 or other standards upon
which the Parties may mutually agree.

     5.   Ameritech shall provide access, where available, to eyewash stations, 
shower stations, bathrooms, and drinking water within the Collocated facility on
a twenty-four (24) hours per day, seven (7) days per week basis for Focal 
personnel and its designated agents.

     6.   Ameritech shall provide all ingress and egress of fiber cabling to 
Focal Collocated spaces in compliance with Focal's request for cable diversity. 
The specific level of diversity required for each site or Network Element will 
be provided in the request for Collocation. Focal will pay any additional costs 
incurred by Ameritech to meet any special diversity requirements of Focal which 
are beyond those normally provided by Ameritech.

     7.   Ameritech shall provide Focal with written notice five (5) Business 
Days prior to those instances where Ameritech or its subcontractors may be 
performing nonemergency work that may affect the Collocated space occupied by 
Focal or the AC and DC power plants that support Focal equipment. Ameritech will
inform Focal by telephone or any emergency-related activity that Ameritech or 
its subcontractors may be performing that may affect the Collocated space 
occupied by Focal or the AC and DC power plants that support Focal equipment. 
Notification of any emergency-related activity shall be made as soon as 
practicable after Ameritech learns that such emergency activity is necessary but
in no event longer than thirty (30) minutes after such time. By the end of
Contract Month 3/25/ the Implementation Team will agree upon the process for
                 --
the notification required by this Section (the "EMERGENCY NOTIFICATION 
PROCESS"). To the extent that the Emergency Notification Process requires 
Ameritech to incur additional costs, Focal shall reimburse Ameritech for such 
costs.

__________________

/25/     Since the terms of this Agreement are the result of Focal's adoption
 --
         under Section 252(i) of the Act of the AT&T Agreement, the Parties
         agree that the term "Contract Month 3", for purposes of this SECTION 7
                                                                      ---------
         OF SCHEDULE 12.15, shall expire on April 30, 1999.
         -----------------

                                Sch. 12.15 - 1
<PAGE>
 
     8. Focal shall not be required by Ameritech to relocate its equipment
during the Initial Term or any Renewal Term. If Focal, at Ameritech's request,
agrees to relocate its equipment, then Ameritech shall reimburse Focal for any
and all costs reasonably associated with such relocation.

     9. Should Ameritech sell or lease a Central Office or any portion thereof
to a third person during the Initial Term or any Renewal Term, Ameritech shall
require such third person to comply fully with the applicable terms and
conditions of this Agreement as they relate to such third person.

    10. Power as referenced in this SCHEDULE 12.15 refers to any electrical
                                    ---------------                        
power source supplied by Ameritech for Focal equipment. It includes all
superstructure, infrastructure, and overhead facilities, including cable, cable
racks and bus bars. Ameritech will supply power to support Focal equipment at
equipment specific DC and AC voltages as mutually agreed upon by the Parties.
Ameritech shall supply power to Focal at parity with that provided by Ameritech
to itself or to any third person. If Ameritech performance, availability, or
restoration falls below industry standards, Ameritech shall bring itself into
compliance with such industry standards as soon as technologically feasible.

    11. Subject to space limitations and Focal's compliance with the applicable
request process and payment requirements of this Agreement, Ameritech shall
provide power to meet Focal's reasonable needs for placement of equipment,
Interconnection, or provision of service.

    12. Both Focal's power equipment and Ameritech power equipment supporting
Focal's equipment shall comply with all applicable state and industry standards
(e.g., Bellcore, NEBS and IEEE) or manufacturer's equipment power requirement
 ----
specifications for equipment installation, cabling practices, and physical
equipment layout.

    13. Ameritech will provide Focal with written notification within ten (10)
Business Days of any scheduled AC or DC power work or related activity in the
collocated facility that poses a reasonable risk of cause an outage or any type
of power disruption to Focal equipment located in the Ameritech facility.
Ameritech shall provide Focal prompt notification by telephone of any
emergency power activity.

    14. Power plant alarms shall adhere to Bellcore Network Equipment-Building
System (NEBS) standards TR-EOP-000063.

    15. Cabling shall adhere to Bellcore Network Equipment-Building System
(NEBS) standards TR-EOP-000063.

    16. Ameritech shall provide Lock Out Tag Out and other electrical safety
procedures and devices in accordance with OSHA or industry guidelines.

    17. Ameritech shall within ten (10) Business Days after the initial
walkthrough provide Focal with a copy of any existing drawings showing Focal's
proposed Collocation space and any related Ameritech facilities, and provide
information relating to measurements for necessary Focal cabling which are not
obtainable from the drawings. Any copies of drawings shall be redacted so as not
to provide proprietary information of other carriers. So long as Ameritech
charges other

                                Sch. 12.15 - 2
<PAGE>
 
Telecommunications Carriers for the foregoing drawings and information, Focal
shall reimburse Ameritech for the costs, if any, incurred by Ameritech to
provide Focal with the foregoing drawings and information.

                                Sch. 12.15 - 3
<PAGE>
 
                                SCHEDULE 12.16

          ADDITIONAL REQUIREMENTS APPLICABLE TO PHYSICAL COLLOCATION

    The following additional requirements shall be applicable to Physical
Collocation only:

    1. Subject to space limitations and Focal's compliance with the applicable
request process and payment requirements for the space, Ameritech shall provide
space, as requested by Focal, to meet Focal's needs for placement of equipment
necessary for Interconnection and access to Network Elements.

    2. Ameritech shall allow requests for contiguous space in increments of 100
ft /2/ if the space is not subject to outstanding requests by other
Telecommunications Carriers.

    3. Other than reasonable security restrictions, Ameritech shall place no
restriction on access to the Focal Collocated space by Focal's employees and
designated agents. Such space shall be available to Focal designated agents
twenty-four (24) hours per day each day of the week. In no case should any
reasonable security restrictions be more restrictive than those Ameritech places
on its own personnel or independent contractors.

    4. For each building in which Collocated space is provided and upon request
by Focal for that building, Ameritech will, at its option, either certify that
the building complies with all applicable environmental, health and safety
regulations or complete an Environmental, Health & Safety Questionnaire provided
by Focal. Focal may provide this questionnaire with its request for Collocation
and Ameritech shall return it or the applicable certification to Focal within
ten (10) Business Days after Ameritech's receipt thereof.

    5. Ameritech shall permit Focal to install, on equipment node enclosures, an
intrusion alarm that can be remotely monitored by Focal's work center,
provided, however, that no such Focal-installed equipment shall interfere with
-----------------
the existing use of the Central Office.

    6. Ameritech shall construct the collocated space in compliance with Focal's
request for Collocation for cable holes, ground bars, doors, and convenience
outlets as such are requested by Focal at prices to be determined.

    7. Focal shall not require advance approval from Ameritech to make
improvements or alterations to the Collocated equipment configuration that are
not substantial and do not require additional power.

    8. Central Office power supplied by Ameritech into the Focal equipment area
shall be supplied in the form of fused power feeds from Ameritech's main power
distribution board to Focal's BDFB located in the designated Focal equipment
area. The power feeders (cables) shall efficiently and

                                Sch. 12.16 - 1
<PAGE>
 
economically support the requested quantity and capacity of Focal equipment.
The termination location shall be as mutually agreed upon by the Parties.

    9.  Ameritech power equipment supporting Focal's equipment shall:

    (a) Provide appropriate Central Office ground, connected to a ground
        electrode located within the Focal collocated space, at a level above
        the top of Focal's equipment plus or minus two (2) feet to the left or
        right of Focal's final request; and

    (b) Provide feeder capacity and quantity to support the ultimate equipment
        layout for Focal equipment upon completion of the equipment node
        construction in accordance with Focal's request for Collocation.

    10. Ameritech shall within ten (10) Business Days after the initial
walkthrough provide Focal with (i) documentation submitted to and received from
contractors for any work being done on behalf of Focal that will be billed as
extraordinary expenses; and (ii) a parallel installation sequence.

    11. Ameritech shall secure external access to the Physical Collocation space
in its Premises in the same or equivalent manner that Ameritech secures external
access to spaces that house Ameritech's equipment.

    12. Ameritech shall within (30) days of the Effective Date provide to Focal
(i) work restriction guidelines related to any restrictions on the manner in
which an Focal contractor can perform work on Ameritech's Premises and (ii) a
list of Ameritech technical guidelines applicable to the collocation of
equipment in Ameritech's Premises. Focal acknowledges that it is responsible to
order such technical guidelines at its cost and expense. Ameritech will notify
Focal in a timely manner of any changes to such work restriction and technical
guidelines.

                                Sch. 12.16 - 2
<PAGE>
 
                                SCHEDULE 16.10

                            3D AND CONDO AGREEMENTS


None.





                                Sch. 16.10 - 1
<PAGE>
 
                                SCHEDULE 30.19

                           PRE EXISTING ARRANGEMENTS


None.




                                Sch. 30.19 - 1
<PAGE>
 
                        PRICING SCHEDULE -- MICHIGAN/1/


               ITEM I -- EMERGENCY NUMBER SERVICE ACCESS (ENSA) 

See Exhibit PS-I 


                      ITEM II -- RECIPROCAL COMPENSATION 

A. End Office Local Termination                   $.004053 per minute 
                                                                    
B. Tandem Switching                               $.000698 per minute 
                                                                    
C. Tandem Transport Termination                   $.000260 per minute 
                                                                    
D. Tandem Transport Facility Mileage              $.000006 per minute, per mile 


                   ITEM III -- INFORMATION SERVICES TRAFFIC 

Information Services Billing and Collection:      $0.03 per message 


                         ITEM IV -- BLV/BLVI TRAFFIC 

A. Busy Line Verification (BLV):                  $0.613 per use
                                                                
B. Busy Line Verification Interrupt (BLVI):       $0.753 per use 
   (in addition to BLV charge)

                                   
______________

/1/  Certain of the rates, charges and prices contained in this Pricing Schedule
     have been established by the Commission pursuant to its July 14, 1997
     and January 28, 1998 orders (collectively, the "Rate Order") in MPSC Case
     No. U-11280 (the "Permanent Rate Docket"). If the Commission determines
     that the rates, charges and prices set forth herein are inconsistent with
     the Commission's decision in the Permanent Rate Docket, either Party shall,
     upon written notice to the other Party, have the right to include or
     substitute rates, charges and prices that confirm to the Permanent Rate
     Docket. Notwithstanding anything to the contrary in this Agreement,
     including Section 29.3. if the Commission, a court or other tribunal
               -------------
     of competent jurisdiction issues an order or decision modifying the Rate
     Order (a "Modifying Order"), either Party shall, upon written notice to the
     other Party, have the right to require that this Agreement be amended to
     reflect such Modifying Order and such amended or new rates, charges or
     prices shall be effective as if such rates, charges and prices were
     originally established in the applicable Rate Order.

                                     PS-1
<PAGE>
 
                     ITEM V -- UNBUNDLED NETWORK ELEMENTS

A.  Unbundled Loop Rates
 
    1.  Recurring Rates
 

<TABLE>
<CAPTION>
                                                     Monthly Rates 
                                                     Access Area/2/
                                                                 -
                                                   A       B       C
                                                 ------  ------  ------ 
        <S>                                      <C>     <C>     <C>  
        2-Wire Analog

            Basic                                $ 9.43  $12.02  $14.86

            Ground Start                         $10.17  $13.21  $15.89

            Electronic Key Line                  $14.63  $20.40  $22.08

        4-Wire Analg                             $22.46  $30.05  $34.90
                                             
        Digital

            ISDN                                 $11.22  $14.92  $17.35
                                                         
            4-wire 64 Kbps                       $60.29  $60.24  $60.06
                                                         
            4-wire 1.544 Mbps                    $92.88  $71.06  $64.58
                                                                         
            2-wire ADSL/HDSL                                            
            Compatible                           $ 9.43  $12.02  $14.86  
                                                                         
            4-wire HDSL Compatible               $22.46  $30.05  $34.90  

        Cross-Connect Charge (additional,
        per cross-connect):

            2-wire                               $ 0.17
                                                      
            4-wire                               $ 0.34
                                                      
            6-wire                               $ 0.51
                                                      
            8-wire                               $ 0.68
                                                      
            DS1                                  $ 0.46
</TABLE> 

                           
_____________
                                             
/2/  "Access Area" is as defined in Ameritech's applicable tariffs for business
 -                                                                            
     and residential Exchange Line Services.

                                     PS-2
<PAGE>
 
<TABLE>
<CAPTION>
                                                 A          B            C 
                                             ---------  --------      --------
 <S>                                         <C>        <C>           <C> 
           DS3                                 $ 0.84   
                                                        
        Service Coordination Fee,              $ 0.84   
        Per Carrier Bill, per Switch                    
                                               
    2.  Non-Recurring Rates                    
                                               
        Service Order -- Establish/Change:   
        (Business or Residence)                $ 6.42/3/   
                                                         
        Line Connection: (Business or          
        Resident)                              $18.60/4/   
                                             
        Record Change                          $ 6.42
                                                    
        Provisioning Change                    $ 6.42

 B. NID/5/ No Charge
        -           


 C. Switching

    1.  Unbundled Local Switching

                                                        Non-Recurring   Monthly 
                                                        -------------   -------

        (a)  Custom Routing
             - per new LCC, per switch                     $114.68           --
                                                                               
        (b)  ULS Ports                                     
                                                           
             - Basic Line Port, per port                   $ 26.83        $2.27
                                                                                
             - Ground Start Line Port, per port            $ 26.83        $2.77
</TABLE> 
                                                 

_____________ 

/3/  The Service Order Charge is a per occasion charge applicable to any number
 -
     of Loops ordered for the same location and same Customer account.

/4/  The Line Connection Charge applies to each Loop.
 -

/5/  Access to Network Interface Device for Accessing Customer Premises Wiring
 -
     (Inside Wire).

                                     PS-3
<PAGE>
 
<TABLE>
<CAPTION>
                                                   Non-Recurring     Monthly
                                                   -------------     -------
 <S>                                               <C>               <C> 
     - ISDN-Direct Port,
        per port                                      $ 26.83        $ 12.41 
        per telephone number                               --        $  0.01 
                                                                             
     - DID Trunk Port,                                                       
        per port                                      $ 26.83        $ 13.26 
        per telephone number                               --        $  0.01 
        add/rearrange each termination                $ 12.17             -- 
                                                                             
     - ISDN Prime Trunk Port,                                                
        per port                                      $309.24        $159.23 
        per telephone number                               --        $  0.01 
        add/rearrange channels                        $ 12.17            --  
                                                                             
        - Digital Trunking Trunk Port,                $309.24        $114.75 
        per port                                                             
                                                                             
        - Custom Routing Port,                                               
        per port                                      $309.24             -- 
        per individual trunk termination                   --        $ 99.83 
                                                                             
     - Centrex Basic Line Port, per port              $ 26.83        $  2.27 
                                                                             
     - Centrex ISDN Line Port, per port               $ 26.83        $ 12.41 
                                                                             
     - Centrex EKL Line Port, per port                $ 26.83        $  2.78 
                                                                             
     - Centrex Attendant Console Line Port,                                   
        per port                                      $ 53.66        $ 74.78  
                                                                             
 (c) Centrex System Charges                                                    
                                                                               
     - System Features, per common block                   --        $354.86   
                                                                               
     - Common Block establishment, each               $189.07             --   
                                                                               
     - System features change or rearrangement,                                 
        per feature, per occasion                     $ 25.82             --    
                                                                                
     - System feature activation, per feature,                              
        per occasion                                  $105.98             --
</TABLE> 

                                     PS-4
<PAGE>
 
<TABLE>
<CAPTION> 
                                                    Non-Recurring    Monthly
                                                    -------------    -------
<S>                                                 <C>              <C> 
   (d) Service Charges

       Service Ordering Charges

       - Initial 
         -------                                                
           Line port, per occasion                     $     6.42           --
           Trunk port, per occasion                    $   167.76           --
                                                                
       - Subsequent                                             
         ----------                                             
           per occasion                                $     6.42           --
                                                                
       -   Record Order per occasion                   $     6.65           --
                                                                
       Conversion Charge                                        
                                                                
       -   change from one type of line-port                     
           to another, per each changed                $    24.64           --

       Ameritech Cross-Connection Service, per
       carrier transport facility,
       -   2-Wire (Line port), each                            --    $    0.17 
       -   DS1 (trunk port) (each individual trunk)            --    $    0.46
 
   (e) Service Coordination Fee
       - per carrier bill, per switch.                         --    $    0.84

   (f) Subsequent Training 
       - per Company person, per hour                  $    33.41           --
                                                                   
   (g) ULS Usage                                                   
       - Billing Development                           $14,734.57           --

       - Per minute of use or fraction thereafter                    $0.003164
                                                                              
       - Daily Usage Feed per message                                $0.000789 

2. Unbundled Tandem Switching

   Tandem Trunk (DS1), including features              $   310.31    $  131.06 

   Service Order Charge                                $   167.76
                                                                
   Cross-Connect Charge, per DS1                                     $    0.46
                                                                
   Subsequent Changes                                  $    12.17           --
</TABLE> 

                                     PS-5
<PAGE>
 
                                                    Non-Recurring    Monthly
                                                    -------------    -------


                                                       Per Minute
                                                       ----------

Usage Without Tandem Trunks                             $0.000756
                            
D. Dedicated Interoffice Transmission Facility

<TABLE>
<CAPTION>
                                                    Non-Recurring    Monthly
                                                    -------------    -------
   <S>                                              <C>              <C> 
   1.  DS1 Rates
       Entrance Facility
       Per point of Termination
         Terminating Bit Rate 1.544 Mbps

       Zone 1                                                  --     $92.88
       Zone 2                                                  --     $71.06
       Zone 3                                                  --     $64.58

       Interoffice Mileage Termination     
       Per point of Termination 1.544 Mbps 
                                           
       Zone 1                                                  --     $14.66
       Zone 2                                                  --     $14.66
       Zone 3                                                  --     $14.66
                                           
       Interoffice Mileage Per Mile 1.544  
       Mbps                                
                                           
       Zone 1                                                  --     $ 1.37
       Zone 2                                                  --     $ 1.37
       Zone 3                                                  --     $ 1.37
                                           
       Optional Features and Functions Clear
       Channel Capability                  
       Per 1.544 Mbps Circuit Arrange       

       Zone 1                                           $  189.84         --
       Zone 2                                           $  189.84         --
       Zone 3                                           $  189.84         --
</TABLE> 

                                     PS-6
<PAGE>
 
                                                    Non-Recurring    Monthly
                                                    -------------    -------

       Interconnection Central Office      
       Multiplexing                        
                                           
       DS1 to Voice/Base Rate/128.0, 256.0,
       384.0 Kbps Transport                 

       Zone 1                                                 --     $334.09
       Zone 2                                                 --     $334.09
       Zone 3                                                 --     $334.09

   2.  DS3 Rates                             
       Entrance Facility, per Point of       
       Termination                           
          DS3 with Electrical Interface Per   
          Termination

       Zone 1                                                 --     $719.52 
       Zone 2                                                 --     $810.59 
       Zone 3                                                 --     $793.90
                                                                            
       Interoffice Mileage Termination                                        
       Per Point of Termination                                               
                                                                              
       Zone 1                                                 --     $144.97  
       Zone 2                                                 --     $144.97  
       Zone 3                                                 --     $144.97  
                                                                              
       Interoffice Mileage Per Mile                                            
                                                                               
       Zone 1                                                 --     $ 29.16   
       Zone 2                                                 --     $ 29.16   
       Zone 3                                                 --     $ 29.16   
                                                                               
       Optional Features and Functions                                         
                                                                              
       Interconnection - Central Office                                        
       Multiplexing, Per Arrangement

       DS3 to DS1 

       Zone 1                                                 --     $383.31
       Zone 2                                                 --     $383.31
       Zone 3                                                 --     $383.31

                                     PS-7
<PAGE>
 
<TABLE>
<CAPTION>
                                                    Non-Recurring    Monthly
                                                    -------------    -------
<S>                                                 <C>              <C>  
3. OC-3 Rates Entrance Facility, per       
   point of termination
   Terminating Bit Rate 155.52 Mbps                                  $326.74
                                                                           
   Interoffice Mileage Termination,                                          
   per point of mileage termination                                          
   155.52 Mbps                                                       $347.19 
                                                                             
   Interoffice Mileage, per mile                                              
   155.52 Mbps                                                       $204.80  
                                                                              
   Optional Features and Functions                                             
                                                                               
   OC-3 Add/Drop Multiplexing, per                                             
   arrangement                                                       $562.48    
                                                                                
   Add/Drop Function                                                           
   Per DS3 Add or Drop                                               $126.22   
   Per DS1 Add or Drop                                               $ 38.99   
                                                                               
   1 + 1 Protection, per OC-3 Entrance                                          
   Facility                                                          $ 49.92    
                                                                                
   1 + 1 Protection with Cable                                               
   Survivability, per OC-3 Entrance                                          
   Facility                                           $1,261.80      $ 49.92 
                                                                             
   Cross-Connection of Services OC-3 to                                      
   OC-3 Cross-Connect, per circuit                                   $ 92.22 
                                                             --              
   1 + 1 Protection with Route                                                  
   Survivability                                                              
                                                    Apply 1 + 1 Protection, per 
   (1) Per OC-3 Entrance Facility                   OC-3 Entrance Facility Rates
                                                    and Charges as specified    
                                                    above plus (2) below      

   (2) Per Quarter Route Mile                                        $ 41.14  
                                                                             
4. OC-12 Rates                                                                

   Entrance Facility, per point of 
   termination, Terminating Bit 
   Rate 622.08 Mbps                                                  $530.35   
</TABLE> 

                                     PS-8
<PAGE>
 
<TABLE>
<CAPTION>
                                                    Non-Recurring    Monthly
                                                    -------------    -------
<S>                                                 <C>              <C>  
   Interoffice Mileage Termination, 
   per point of mileage termination 
   622.08 Mbps                                                       $  589.98 
                                                                           
   Interoffice Mileage, per mile                                     
   622.08 Mbps                                                       $  371.24
                                                                            
   Optional Features and Functions                                          
                                                                            
   OC-12 Add/Drop Multiplexing, per                                         
   arrangement                                                       $  630.21
                                                                            
   Add/Drop Function                                                        
                                                                            
   Per OC-3 Add or Drop                                              $  175.82
   Per DS3 Add or Drop                                                   38.12

   Cross-Connection of Services 
   OC-12 to OC-12 Cross-Connect, 
   per circuit                                                       $  486.16
                                                                           
   1 + 1 Protection, per OC- 12                                              
   Entrance Facility                                                 $  246.97 

   1 + 1 Protection with Cable 
   Survivability, per OC-12 
   entrance facility                                    $1,261.80    $  246.97 

   1 + 1 Protection with Route                                                
   Survivability 

   (1) Per OC-12 Entrance Facility                 Apply 1 + 1 Protection, per  
                                                   OC-12 Entrance Facility Rates
                                                   and Charges as specified     
                                                   above plus (2) below         

   (2) Per Quarter Route Mile                                        $   36.97 
                                                                             
5. OC - 48 Rates                                                     
                                                                     
   Entrance Facility, per point of                                   
   termination Terminating Bit Rate                                  
   2488.32 Mbps                                                      $2,233.48
                                                                              
   Interoffice Mileage Termination, per                              
   point of mileage termination 2488.32                               
   Mbps                                                              $1,364.94
                                                                              
   Interoffice Mileage, per mile 2488.32                             
   Mbps                                                              $  239.33
</TABLE> 

                                     PS-9
<PAGE>
 
<TABLE>
<CAPTION>
                                                    Non-Recurring    Monthly
                                                    -------------    -------
       <S>                                          <C>              <C> 
       Optional Features and Functions

       OC-48 Add/Drop Multiplexing, per 
       arrangement (not to exceed 12 
       DS3s or equivalent)                                           $  732.90
                                                                             
       Add/Drop Function                                                      
       Per OC-12 Add or Drop                                         $  346.13
       Per OC-3 Add or Drop                                          $  159.92
       Per DS3 Add or Drop                                           $   57.27
                                                                              
       Cross-Connection of Services OC-48                                     
       to OC-48 Cross-Connect, per circuit                           $1,074.81
                                                                              
       1 + 1 Protection, per OC-48                                            
       entrance facility                                             $  930.44

       1 + 1 Protection with Cable 
       Survivability, per OC-48 entrance               $1,261.80     $  930.44
       facility

       1 + 1 Protection with Route 
       Survivability

       (1) Per OC-48 Entrance Facility             Apply 1 + 1 Protection, per 
           Channel                                 OC-48 Entrance Facility Rates
                                                   and Charges as specified    
                                                   above plus (2) below   

       (2) Per Quarter Route Mile                                    $   61.60 
</TABLE> 


<TABLE>
<CAPTION> 
                                                   Design and               
                                                 Central Office     Carrier 
                                                   Connection     Connection
                               Administration     Charge, per     Charge, per
                                Charge, per         circuit       termination
                                -----------      --------------   -----------
                                   order                                    
                                   -----                                     
<S>                            <C>               <C>              <C> 
6. Installation and
   Rearrangement
   Charges DS1
   Service 1.544 Mbps
</TABLE> 
 
                                     PS-10
<PAGE>
 
<TABLE>
<CAPTION>
                                                   Design and               
                                                 Central Office     Carrier 
                                                   Connection     Connection
                               Administration     Charge, per     Charge, per
                                Charge, per         circuit       termination
                                -----------      --------------   -----------
                                   order                                    
                                   -----                                     
          <S>                  <C>               <C>              <C> 
          Zone 1                   $169.14        $267.42            $244.02  
          Zone 2                   $169.14        $267.42            $244.02
          Zone 3                   $169.14        $267.42            $244.02

          DS3 Service 44.736
          Mbps

          Zone 1                   $128.09        $284.49            $157.75
          Zone 2                   $128.09        $284.49            $157.75
          Zone 3                   $128.09        $284.49            $157.75

          OC-3 Service
          155.52 Mbps              $ 51.93        $211.01            $414.21

          OC-12 Service
          622.08 Mbps              $ 51.93        $211.01            $414.21

          OC-48 Service
          2488.32 Mbps             $ 51.93        $211.01            $414.21
</TABLE>


E.   Shared Interoffice Transmission Facilities

     The rates, charges and prices for Shared Interoffice Transmission
     Facilities are the following elements set forth in F.C.C. Tariff No. 2
     Sections 6.1.3 and 6.9.1: (i) Tandem-Switched Termination per Access
     Minute and (ii) Tandem-Switched Facility per Access Minute per Mile. To the
     extent that Requesting Carrier also purchases Tandem Switching, Requesting
     Carrier shall compensate Ameritech for such Tandem Switching at the
     applicable rates set forth on Item V (C) (2) of the Pricing Schedule in
     addition to any applicable charges for Shared Interoffice Transmission
     Facilities.

                                     PS-11
<PAGE>
 
<TABLE>
<CAPTION>
                                                       Non-Recurring       Monthly        Usage
                                                       -------------       -------        -----
<S>                                                    <C>                 <C>            <C> 
F. Transiting (local and intraLATA toll):

   Tandem Switching per minute                                   --             --        $0.004002
   Tandem Transport per minute                                   --             --        $0.000260
   Tandem Transport Facility per minute                          --             --        $0.000084

G. Signaling Networks and Call-Related
   Databases

   1. Signaling Networks (signal Links as per
      MPSC No. 21, Part 8)

      Signal Transfer Point, per port                       $254.79        $270.11               --

      Originating Point Code, per service 
      added or changed                                      $  9.63             --               -- 
                                                          
      Global Title Address Translation, per service       
      added or changed                                      $  5.18             --               -- 
                                                          
      Signal Switching, per ISUP message                         --             --        $0.000121
                                                                                                  
      Signal Switching, per TCAP message                         --             --        $0.000103
                                                                                                  
      Signal Transport, per ISUP message                         --             --        $0.000046
                                                                                                  
      Signal Transport, per TCAP message                         --             --        $0.000031
                                                                                                  
      Signal Formulation, per ISUP message                                                $0.000699
                                                                                                  
      Signal Formulation, per TCAP message                                                $0.000417
                                                                                                  
      Signal Tandem Switching, per ISUP message                                           $0.000207


                                                                                     Per Query
                                                                                     ---------

   2. Call-Related Databases

      800 Service 

      Database Query Using Ameritech - Provided 
      Facilities

      - 80ODB Call-Routing Query                                                          $0.002837 
</TABLE> 

                                     PS-12
<PAGE>
 
                                                                      Per Query
                                                                      ---------

      - 80ODB Routing Options Query                                   $0.000930

      Local STP Database Query Utilizing Requesting
      Carrier Provided Facilities between the Requesting
      Carrier's Switch and Ameritech's STP and
      Ameritech Provided Facilities between Ameritech's
      STP and Ameritech's Regional STP

      - 80ODB Carrier-ID-Only Query                                   $0.001227 
                                   
      - 80ODB Routing Options Query                                   $0.000185
                                                                              
      Regional STP Database Query Utilizing Requesting                
      Carrier - Provided Facilities                                   
                                                                      
      - 80ODB Carrier-ID-Only Query                                   $0.001170
                                                                               
      - 80ODB Routing Options Query                                   $0.000131 

      LIDB Service
                  
      LIDB Queries 

      - LIDB Validation Query                                         $0.013817
      - LIDB Transport Query                                          $0.000069
      - LIDB to LIDB Query                                            $0.048058
                                                                              
      Query at regional STP                                                   
      - LIDB Validation Query                                         $0.013817
      - LIDB Transport Query                                          $0.000013

      Ameritech Provided Services requiring LIDB Queries 

      - LIDB Validation Query                                         $0.013817 
          - LIDB Transport Query                                      $0.000813 
          - LIDB to LIDB Query                                        $0.048803 


   3. Service Management Systems 

      Access to Databases - TBD/6/
      --------------------      - 


_________________

/6/  "TBD" means "to be determined." The rate structure set forth herein may
 -
     ultimately be modified.

                                 PS-13
<PAGE>
 
H.   Operator Services and Directory Assistance

     1. Operator Services

        Manual Call Assistance Occurrences - rates will apply based on the total
        -----------------------------------                                     
        monthly volume and a LIDB charge will apply separately to all
        occurrences requiring billing validation.

        $0.340 per occurrence

        Automated Call Assistance Occurrences - rates will apply based on the
        --------------------------------------                               
        total monthly volume, and a LIDB charge will apply separately to all
        automated occurrences.

        $0.018 per occurrence

        Branding per trunk group  --  $386.56 non-recurring charge 

     2. Directory Assistance

           Directory Assistance, rate per call $0.205

I.   Combinations of Network Elements /7/  
                                       -

J.   Rates for Maintenance. 

     1. Trip Charge -- as per Ameritech's Retail Tariff 

     2. Time Charge -- as per Ameritech's Retail Tariff 


                     ITEM VI -- WHOLESALE RESALE SERVICES

A.   See Schedule 10.1

B.   "Warm" Transfer          TBD



                            ITEM VII -- COLLOCATION

A. Physical

                                                       
______________

/7/  Charges for Combinations of Network Elements are determined based on
 -   
     charges set forth in this Pricing Schedule for individual elements as
     defined in Schedule 9.3.4. Notwithstanding anything to the contrary,
                ----------------                                         
     Ameritech is not waiving its right to amend this Agreement pursuant to
     Section 29.3.
     -------------

                                    PS-14
<PAGE>
 
<TABLE>
<CAPTION>
Description                                        Recurring   Non-Recurrin
-----------                                        ---------   ------------ 
<S>                                                <C>         <C> 
Order Charge                                              --
   - Per ACOI Application                                 --     $   123.17

      Central Office Floor Space                                         
         - Per 100 Sq. Ft.                           $703.69             --   

      Central Office Build Out
- Per Initial 100 Sq. Ft. of Floor Space
      Requested, Per Central Office                       --     $12,482.36
         - 50 % charge                                    --     $ 6,241.18 
         - 25 % charge                                    --     $ 3,120.59

- Per Additional 100 Sq. Ft. of Floor Space 
Requested, Per Central Office                             --     $ 5,342.22
   - 50 % charge                                          --     $ 2,671.11
   - 25 % charge                                          --     $ 1,335.56

Cable Vault Splicing
   - Per Initial Splice                                   --     $    90.26 
   - Per Subsequent Splice                                --     $     6.61
  
Splice Testing
   - Per Initial Splice Test                              --     $    20.73 
   - Per Additional Splice Test                           --     $     1.22

Cable Pulling From Manhole to Cable Vault
   - Per First Foot                                       --     $    98.04
   - Per Additional Foot                                  --     $     0.49

Cable Pulling From Cable Vault to 
Transmission Node
   - Per First Foot                                       --     $    36.59 
   - Per Additional Foot                                  --     $     0.37

Riser Space
   - Per Foot                                        $  1.05             --

Entrance Conduit
   - Per Inner Duct, per Foot                        $  0.05             --

Power Consumption
   - Per Fuse AMP                                    $  5.73             --     

Power Delivery
   - Per Power Lead                                       --     $   751.63
</TABLE> 

                                    PS-15
<PAGE>
 
<TABLE>
<CAPTION>
     Description                                     Recurring    Non-Recurring
     -----------                                     ---------    -------------
<S>                                                  <C>          <C>   
     200 Conductor Electrical Cross-Connection
     Block
        - Per 200 Conductor Electrical Cross-          $69.78                --
        Connection Block                                    
                                                       
     Digital Cross-Connection Panel (DSX)              
        - Per DSX-3 Termination (1 DS3                 
        termination)                                   $16.61                --
        - Per DSX-1 Panel (Up to 56 DS1                     
        terminations)                                  $52.04                --

     Optical Cross-Connection Panel (OCX)
        - Per OCX Panel Segment                        $ 6.25                --
                                                           
     Space Reservation Charge                           
        - Per Reservation Request                          --         $  304.78

     Optional Features and Functions

     Transmission Node Enclosure
        - Per First 100 sq. ft. Enclosed                   --         $1,850.41 
        - Per Additional 100 sq. ft. Enclosed              --         $  730.79

     Passive Bay Termination (includes Bay and 
     Panel)                                            $ 0.58                --
        - DS1 Termination                              $ 7.32                --
        - DS3 Termination
 
     200 Conductor Electrical Termination Block
     (outside Transmission Node)
        - Per Termination Block                        $69.78                --

     Digital Timing Source
        - Per Sync Signal Provided                     $14.00                -- 

     DS1 Repeater                                      $ 6.49                --

     DS3 Repeater                                      $37.69                --

     Diverse Riser
        - Per floor traversed                              --         $  224.84

B.   Virtual
     Service Order Charge
        - Per Order                                        --         $   48.09 
</TABLE> 

                                     PS-16
<PAGE>
 
<TABLE>
<CAPTION>
Description                                          Recurring    Non-Recurring
-----------                                          ---------    -------------
<S>                                                  <C>          <C>   
Optical Line   Entrance Facility
    - Per Foot                                        $ 0.05/8/              --
                                                             -

Riser
    - Space Per Foot                                  $ 0.24                 -- 
    - Per Fiber Termination                           $ 1.65                 --

Cable Vault Splicing
    - Per Initial Splice                                  --           $  90.26
    - Per Subsequent Splice                               --           $   6.61

Splice Testing
    - Per Initial Splice Test                             --           $  20.73
    - Per Subsequent Splice Test                          --           $   1.22 

Cable Pulling From Manhole to Cable Vault
    - Per First Foot                                      --           $  98.04 
    - Per Additional Foot                                 --           $   0.49 
                                                                               
Cable Pulling From Cable Vault to the LGX Panel                        $  36.59
    - Per First Foot                                      --           $   0.37
    - Per Additional Foot                                 --                    
                                                                              
Diverse Riser                                                                   
    - Per floor traversed                                 --           $ 224.84 

Equipment Bay
    - Per 7' Bay Installed (Ameritech
    provided/installed/pre-packaged)                  $41.17           $ 164.00

Equipment Bay
    - Per 7' Bay Installed (Requesting
    Carrier provided/installed)                       $26.33                 --/9/

Project Management Fee
    - Per Initial 7' Bay Installed on Initial or
    Subsequent Order                                      --           $1219.12

    - Per Additional 7' Bay Installed on
    Initial or Subsequent Order                           --           $ 609.56
</TABLE> 

___________________
/8/  Rates indicated do not include cable.
 -

/9/  Rates indicated do not include cable.
 -

                                     PS-17
<PAGE>
 
<TABLE>
<CAPTION>
Description                                          Recurring    Non-Recurring
-----------                                          ---------    -------------
<S>                                                  <C>          <C>
    - Per Initial Shelf Installed 
    on Subsequent Order                                     --        $914.34
                                                                            
    - Per Additional Shelf Installed on Same                --        $548.61
    Subsequent Order                         
 
    - Per Bay Rearrangement and/or
    Miscellaneous Work                                      --        $731.47
 
Power Consumption
    - Per Fuse AMP                                      $ 5.73             --

Power Delivery
    - Per 7' Bay Installed                                  --        $751.63

200 Conductor Electrical Cross-Connection 
Block
    - Per 200 Conductor Electrical                      $69.78             -- 
    Cross-Connection Block

Digital Cross-Connection Panel (DSX) 
    - Per DSX-3 Termination (1 DS3
    termination)                                        $16.61             --

    - Per DSX-1 Panel (Up to 56 DS1 
    terminations)                                       $52.04             --

Optical Cross-Connection Panel (OCX)
    - Per OCX Panel Segment                             $ 6.25             -- 

Digital Timing Source
    - Per Timing Circuit Required                       $ 2.79             --

    Thru-Connect
    - Per DSX-1 to DSX-1                                $ 0.21        $  2.92
    - Per OCX to OCX                                    $ 1.60        $  2.92
</TABLE> 


                            ITEM VIII -- STRUCTURE

See Exhibit PS-VIII.

                                     PS-18
<PAGE>
 
                ITEM IX --- SERVICE PROVIDER NUMBER PORTABILITY

                                                      I.N.C./10/  Per Month/10/
                                                      -----  --   --------- --
  A. SPNP-Remote
     Service Ordering Charge, per occasion/11/        $ 31.05 
                                           --
     per number ported                                $ 11.20        $  2.84 
     per additional call path/12/ (1-5)               $  5.85        $  0.09
                              --
     per additional call path (6-90)                  $  5.85        $  0.34 


  B. SPNP-Direct

     Service Ordering Charge, per occasion            $ 47.56


     Service Establishment Charge
        per SPNP-Direct trunk group,
        per switch                                    $ 31.77            --- 

     SPNP-Direct Channel Termination                     
        charges, per SPNP-Direct VG
        channel termination                           $ 19.60        $ 20.05
         per SPNP-Direct DS1 
        channel termination                           $159.02        $132.16
                                                         

______________________

/10/ Rates suspended pending Commission approval of a competitively neutral cost
 --  
     recovery mechanism.
     
/11/ Service Coordination Fee Charges apply.
 --

/12/ Service Ordering charges for additional call capacity for a ported number
 --  
     are not applicable if ordered coincident with its specific ported number.
     If ordered subsequent to SPNP-Remote Service or with an unrelated ported
     number, Service Ordering charges apply per occasion.

                                     PS-19
<PAGE>
 
<TABLE> 
                                               I.N.C. /13/                 Per Month /13/
                                               -----   --                  ---------  -- 
<S>                                            <C>                         <C> 
SPNP-Direct Number Charges
     per number ported                              $ 1.83                   $.034054     

SPNP-Direct Transport Charges,/14//15/
                               --  -- 
     per SPNP-Direct VG transport              See Footnote /16/           See Footnote /16/
                                                             --                          --  
     per SPNP-Direct VG w/o transport/17/ 
                                      --
     per SPNP-Direct DS1 transport             See Footnote /18/           See Footnote /18/      
                                                             --                          --
     per SPNP-Direct DS1 w/o transport/17/
                                       --     
  
Subsequent additions, deletions or
rearrangement of SPNP-Direct trunk
terminations in addition to above
charges
     per occasion                                   $12.13
</TABLE> 

__________________

/13/   Rates suspended pending Commission approval of a competitively neutral
 --    
       cost recovery mechanism.

/14/   Service ordering charges, as shown in Item V, apply.
 --

/15/   Line connection charges, as shown in Item V, apply.
 --

/16/   Rates for unbundled PBX ground start loops apply, as specified in Item V.

/17/   Where SPNP Direct is provisioned, cross-connection charges as specified 
 --    
       in Item V apply.

/18/   SPNP Direct DS1 is provisioned at the rates and charges for DS1 service, 
 --    
       as specified in Item V.D.1 apply.

                                     PS-20

<PAGE>
 
                                 EXHIBIT PS -1

Emergency Number Service Access
(ENSA)

Description                                  Non-Recurring           Monthly
-----------                                  -------------           -------

1. Channel Conditioning
   - Per Channel 
     - Back to Back                               $365.89            $ 32.88  
       Collocated                                 $365.89            $ 32.88
     - Direct (1st Channel) Channels              $357.39            $199.56
       2-24 (per channel)                         $357.39            $  1.88

ANI/ALI/SR and Database Management
- Per 1,000 main stations and
  equivalent network access lines served,
  rounded up to the nearest 1,000                 $  6.81            $ 27.77

Control Office Administration
- Per NXX                                         $122.11            $  2.15  
    
The prices for Route Diversity will be determined on a case by case basis.

The charges for Alternate Control Office Access, enabling routing of 911 calls 
across multiple selective routing areas, is in addition to all other charges,
and subject to Ameritech approval.

                                                       Nonrecurring
                                                       ------------

Alternate Control Office
-  Per Trunk Group                                       $548.24

Address & Routing File (ARF)
-  Per File Request                                      $ 56.50

Manual Updates
-  Per Record, per occasion                              $  1.58


                                Exhibit PS-1-1
<PAGE>
 
                                EXHIBIT PS-VIII
                             STRUCTURE PRICING/1/
                                               -

             POLE ATTACHMENT AND CONDUIT OCCUPANCY ACCOMMODATIONS

                                             Nonrecurring Charge      Per Year
                                             ----------------------------------

Administrative Fee
-  per request or assignment                           $200.00

Pole Attachment Fee
-  per pole, per year for each foot of
   usable space occupied and for each power
   supply or equipment case or cabinet
   attached to a pole                                                $  1.97

Conduit Attachment Fee
-  per foot of innerduct occupied per year                           $   .33/2/ 
                                                                             -
   
________________

/1/  The rates set forth above are currently the charges for the lowest existing
 -   contract available to an attaching party in the state of Michigan and shall
     be adjusted periodically consistent with the terms of the Agreement.

/2/  If an Attaching Party occupies an entire duct, the Attachment Fee shall be 
 -   two (2) times the rate per innerduct foot for the Attachment.

                               Exhibit PS-VIII-1
<PAGE>
 
                                EXHIBIT PS-VIII
                             STRUCTURE PRICING/3/
                                               -

A.   The following fees, rates and charges apply to Attachment to Ameritech
Structure.

     1.   Administrative Fees. Administrative Fees cover the cost of 
establishing records, databases and systems, the processing of assignment of
permits and similar administrative procedures to accommodate a Requesting
Carrier's request for Attachment. Administrative Fees are payable with
Requesting Carrier's initial request for Attachment, and for assignment of any
permit, or series of permits, to a single assignee. Administrative fees are not
refundable.

Administrative Fee - $200.00 per request of assignment.

     2.   Maps, Records and Information Charges. Maps, Records and Information 
charges cover the cost of researching and preparing records and information and 
preparing maps or drawings in order to provide access to the same to a 
Requesting Carrier. Charges for these services will be as follows:

          a. Initial Map Preparation - The full cost to Ameritech to prepare a 
             map or record for access by a Requesting Carrier.

          b. Record Searches and Information Requests - The full cost to
             Ameritech to research records and assemble information to respond
             to a Requesting Carrier's request for information and, if
             applicable, to meet with the Requesting Carrier to clarify the map,
             record or information.

Prior to initiating Initial Map Preparation or Record Searches and Information 
Requests, the Requesting Carrier shall deposit with Ameritech against the 
charges therefor Ameritech's estimated amount of charges associated with the 
requested Initial Map Preparation or Record Search and Information Request. The 
Requesting Carrier shall pay the amount by which the costs of the request 
exceeds the estimate. Ameritech will reimburse to the Requesting Carrier the 
amount by which the deposit exceeds the actual cost of the request.

     3.   Make Ready Work Charges. Make Ready Work Charges include all of 
Ameritech's costs to prepare Structure for the Attachments of the Requesting 
Carrier, including engineering, field surveys, permits, construction, 
rearrangement, replacement, inspections, administration and supervision.

___________________

/3/  The rates set forth above are currently the charges for the lowest existing
 -   contract available to an attaching party in the state of Michigan and shall
     be adjusted periodically consistent with the terms of the Agreement.

                               Exhibit PS-VIII-2
<PAGE>
 
          a.   The charges for Make Ready Work are the full cost to Ameritech to
               perform the required work.

          b.   Prior to commencing any make Ready Work by Ameritech, the
               Requesting Carrier shall deposit with Ameritech against the Make
               Ready Work Charges, Ameritech's estimated amount of the Make
               Ready Work Charges. The Requesting Carrier shall pay the amount
               by which the Make Ready Work Charges exceeds the deposit.
               Ameritech will refund to the Attaching Party the amount by which
               the deposit exceeds the Make Ready Work Charges.

          c.   For requests for access to Ameritech's Ducts, Conduit or Rights-
               of-way, the Requesting Carrier shall make separate deposits for
               field survey Make Ready Work to determine the actual availability
               of space based on Ameritech's records and for the Make Ready Work
               to prepare the Rights-of-way or conduit for the Requesting
               Carrier's Attachment.

          d.   In the event that other Requesting Carriers, including Ameritech,
               share in the responsibility for the modification to Ameritech's
               Structure, the deposits required by this section shall be the
               Requesting Carrier's proportionate share of the Make Ready Work
               Charges.

     4.   Attachment Fees. Attachment Fees are the recurring charges to the 
Requesting Carrier to place and maintain its Attachments in or on Ameritech's 
Structure.

          a.   Attachment Fees are due and payable twice each Contract Year in
               advance. On January 1 of each year, the Requesting Carrier will
               be billed for its Attachments to Ameritech's Structure in place
               and for which Make Ready Work has been completed as of December 1
               of the previous year. On July 1 of each Contract Year, the
               Requesting Carrier will be billed for its Attachments to
               Ameritech's Structure in place and for which Make Ready Work has
               been completed as of June. Any Attachments made within each
               billing period will be billed at the time of the Attachment for
               the entire billing period.

          b.   Pole Attachment Fees

               i)   The Attachment Fee for poles applies to each pole on which
                    the Requesting Carrier has placed it Attachment or for which
                    Make Ready Work pursuant to a request for access has been
                    completed.

               ii)  Pole Attachment Fee: $1.97 per pole, per year for each one
                    foot of space occupied by the Requesting Carrier's
                    Attachments.

                               Exhibit PS-VIII-3
<PAGE>
 
          c.   Duct or Conduit Attachment Fees

               i)   The Attachment Fee for duct or conduit applies to the total
                    number of feet of Ameritech's conduit system or ducts in
                    which the Requesting Carrier placed Attachments or for which
                    Make Ready Work pursuant to a request for access has been
                    completed.

               ii)  The length of the duct or conduit occupied is measured from
                    wall to wall of the manholes, or from the wall of the
                    manhole to the end of the Ameritech's conduit system or duct
                    occupied by the Requesting Carrier's Attachment, plus the
                    cable racking and maintenance loop space measured by the
                    length of the Requesting Carrier's cable within each
                    manhole.

               iii) If Requesting Carrier's partial occupancy of a continuous
                    conduit system or duct renders the remainder of any portion
                    thereof unusable, the Attachment Fee applies to both the
                    portion occupied and the portion unusable.

               iv)  If Requesting Carrier occupies an entire duct, the
                    Attachment Fee shall be twice (2) times the rate per Inner-
                    duct foot for the Attachment.

               v)   Conduit Attachment Fee:

                    $.33 per foot of Inner-duct or cable racking an maintenance 
                    loop space occupied per year.
   
          d.   Rights-of-Way Attachment Fees:

               i)   The Attachment Fee for use of linear rights-of-way applies
                    to the total linear footage of strips of land three feet
                    (3') wide suitable for direct buried or trench placement of
                    cable facilities of Ameritech's right-of-way in which the
                    Requesting Carrier has placed Attachments or for which Make
                    Ready Work pursuant to a request for access has been
                    completed and is priced on a case-by-case basis.

               ii)  If Requesting Carrier's partial occupancy of a continuous
                    linear right-of-way renders the remainder or any portion
                    thereof unusable, the Attachment Fee applies to both the
                    portion occupied and the portion rendered unusable.

               iii) The Attachment Fees for the Requesting Carrier's equipment
                    cabinets or enclosures placed on Ameritech's rights-of-way
                    will be priced on a case-by-case basis, depending upon the
                    proposed Attachment and the characteristics of the right-of-
                    way in question including the consumption of useable space
                    of the right-of-way by the Attachment and its useability for
                    the Attachments of others, including Ameritech's, after the
                    Attachment.

                               Exhibit PS-VIII-4
<PAGE>
 
               iv)  The Attachment Fees for the Requesting Carrier's Attachments
                    to Ameritech's rights-of-way within buildings or on campuses
                    owned by third parties will be priced on a case-by-case
                    basis, depending upon the proposed Attachment and the
                    characteristics of the right-of-way the Attachment and its
                    useability for the Attachments of others, including
                    Ameritech's after the Attachment, and the cost of Ameritech
                    of the right-of-way in question.

          e.   Period Inspection Fees

               Periodic inspection fees will be assessed to cover the Requesting
               Carrier's portion of the costs to Ameritech to make periodic
               inspections of its Structure with respect to the Attachments of
               the Attaching Party and other attaching parties.

                               Exhibit PS-VIII-5
<PAGE>
 
RATE ELEMENT                  MONTHLY CHARGE          NON-RECURRING CHARGE/2/
                                                                           -

 ADMINISTRATIVE CHANGE CHARGE                           $50.00
INITIAL ADDRESS MESSAGE (IAM)- $0.0011500 PER MESSAGE

RECIPROCAL COMPENSATION = $XXXX PER MINUTE FOR LOCAL CALLS /4/
                                                            -


/4/  Ameritech and Focal do not agree on the Reciprocal Compensation rate to be
 -   paid by Ameritech for Local Traffic terminating on Focal's network. Focal
     will bill Ameritech at $0.005956 per minute for Local Traffic. Ameritech
     disagrees and believes the rate is $0.0050000 and will dispute Focal's
     billing in accordance with its rights under Section 28.2 of the Agreement.
     Either Party may reslove the dispute consistent with Section 28.3 of the
     Agreement. The Parties will true-up the difference, if any, after the
     correct rate is determined pursuant to Section 28.3.

                              Exhibit PS-VIII-A-2

<PAGE>
 
                                   Exhibit A
                                   ---------

                          FOCAL/AMERITECH FIBER MEET


                            [DIAGRAM APPEARS HERE]


                               EXHIBIT PS-VIII-A
                    Focal Network Interconnection Services/1/
                                    Michigan
<TABLE>
<CAPTION>
Rate Element                                       Monthly Charge                  Non-recurring Charge/2/
<S>                                                <C>                             <C>
DS1 Collocation Termination Charge per DS1/3/
   1 -   28 DS1s                                      $ 36.00                            $267.00
  29 -   56 DS1s                                      $ 33.00                            $267.00
  57 -   84 DS1s                                      $ 26.00                            $267.00
  85 -  112 DS1s                                      $ 21.00                            $267.00
 113 -  140 DS1s                                      $ 17.00                            $267.00
 141 -  168 DS1s                                      $ 13.00                            $267.00
 169 -  300 DS1s                                      $ 12.00                            $175.00
 301 -  500 DS1s                                      $ 12.00                            $125.00
 501 -  750 DS1s                                      $ 12.00                            $ 75.00
 751 - 1000 DS1s                                      $ 12.00                            $ 50.00
1001+                                                 $ 12.00                            $ 25.00

DS3 to DS1 Multiplexing                               $620.00
 per DS3
Leased DS1 Facility
      w/o mileage                                     $186.00
      w/ mileage                                      $334.00 + $25.00 per mile
Signaling Link Port                                   $450.00                            $475.00
Termination
Installation per DS1 Trunk                                                               $177.50
Group
Service Order Charge Per                                                                 $ 50.00
Order
Engineering Charge per                                                                   $120.00
DS1 Trunk Group
Service Order Change Charge                                                              $ 50.00
</TABLE>

/1/  The rates in this Exhibit are subject to change if the rates Ameritech
     charges Focal for comparable services provided under the Agreement change.

/2/  For moves within the same Focal Wire Center, which are not initiated by
     Focal, the Service Order Charge and one-half of the non-recurring charges
     will apply.

/3/  The DS1 Collocation Termination charge permits the Co-Carrier to
     terminate Co-Carrier provided facilities in the Co-Carrier equipment
     residing within Focal furnished, engineered and installed space and
     includes cross-connect to Focal equipment. It applies per terminated DS1
     and not to spare DS1 capacity or access services Focal purchases from
     Ameritech. However, if a DS3 is terminated and Focal provides multiplexing,
     Ameritech must pay 28 DS1 Collocation Termination charges even if all
     trunks are not used. Ameritech acknowledges that the DS1 Collocation
     Termination charge will be identified on invoices as a "DS1 Port
     Termination Charge."

                              Exhibit PS-VIII-A-1
<PAGE>
 
                        REPRESENTATION OF AUTHORIZATION

     Ameritech hereby represents to Focal, for purposes of obtaining a
Customer's Customer Proprietary Network Information ("CPNI") or for placing an
order to change or establish a Customer's service, that it is a duly
certificated LEC and that it is authorized to obtain CPNI and to place orders
for Telephone Exchange Service (including Resale Service) upon the terms and
conditions contained herein.

1.   With respect to requests for CPNI regarding prospective Customers of
     Ameritech, Ameritech acknowledges that it must obtain written or
     electronic authorization in the form of a signed letter, tape-recorded
     conversation, password verification, or other means ("Documentation of
     Authorization") which explicitly authorizes Ameritech to have access to the
     prospective Customer's CPNI. The Documentation of Authorization must be
     made by the prospective Customer or the prospective Customer's authorized
     representative. In order to obtain the CPNI of the prospective Customer,
     Ameritech must submit to Focal the Documentation of Authorization. If
     Ameritech cannot provide applicable Documentation of Authorization, then
     Focal shall not provide CPNI to Ameritech.

2.   If Ameritech has already obtained Documentation of Authorization for the
     Customer to place an order for Telephone Exchange Service for the Customer,
     Ameritech need not submit Documentation of Authorization to obtain the
     Customer's CPNI.

3.   With respect to placing a service order for Telephone Exchange Service
     (including Resale Services) for a Customer, Ameritech acknowledges that it
     must obtain Documentation of Authorization which explicitly authorizes
     Ameritech to provide Telephone Exchange Service to such Customer. The
     Documentation of Authorization must be made by the prospective Customer or
     Customer's authorized representative. Ameritech need not submit the
     Documentation of Authorization to process a service order. However,
     Ameritech hereby represents that it will not submit a service order to
     Focal unless it has obtained appropriate Documentation of Authorizaton from
     the prospective Customer and has such Documentation of Authorization in its
     possession.

4.   The Documentation of Authorization must clearly and accurately identify 
     Ameritech and the prospective Customer.
 
5.   Ameritech shall retain all Documentation of Authorization in its files for
     as long as Ameritech provides Telephone Exchange Service to the Customer,
     or for as long as Ameritech makes requests for information on behalf of the
     Customer.

6.   Ameritech shall make Documentation of Authorization available for
     inspection by Focal during normal business hours. In addition, Ameritech
     shall provide Documentation of Authorization for Customers or prospective
     Customers to Focal upon request.
 

<PAGE>

7.   Ameritech is responsible for, and shall hold Focal harmless from, any and
     all Losses (as defined in that certain Interconnection Agreement under
     Sections 251 and 252 of the Telecommunications Act of 1996 dated as of
     January 29, 1997 by and between Ameritech Information Industry Services, a
     division of Ameritech Services, Inc. on behalf of and as agent for
     Ameritech Michigan and Focal Communications Corporation of Michigan, (the
     "Interconnection Agreement") resulting from Focal's reliance upon
     Ameritech's representations as to its authority to act on behalf of a
     Customer or prospective Customer in obtaining CPNI or placing a service
     order for Telephone Exchange Service.


8.   If Ameritech fails to repeatedly and materially abide by the procedures set
     forth herein, Focal reserves the right to insist upon the submission of
     Documentation of Authorization for each Customer in connection with a
     request for a service order.

9.   This Representation of Authorization shall commence on the date noted below
     and shall continue in effect until the termination or expiration of the
     Interconnection Agreement.

     Dated this 10th day of February 1999.

AMERITECH INFORMATION INDUSTRY
SERVICES, A DIVISION OF AMERITECH
SERVICES, INC., ON BEHALF OF AND
AS AGENT FOR AMERITECH MICHIGAN

By: /s/ Theodore Edwards
   --------------------------------    
Title: Vice President
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Printed Name: Theodore A. Edwards
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