Document:

<PAGE>   1

                                                                 EXHIBIT 10.18.2

IXC                          AMENDMENT NO. 2 TO IXC
COMMUNICATIONS, INC.        MASTER SERVICE AGREEMENT

This Amendment No. 2 to the Master Service Agreement is made and entered into by
and between IXC COMMUNICATIONS SERVICES, INC., f/k/a IXC Carrier, Inc./IXC Long
Distance, Inc./IXC Broadband Services, Inc. (generically "IXC"), a Delaware
corporation with its principal place of business at 1122 Capital of Texas Hwy.
South, Austin, Texas 78746 ("Supplier"), and UNIVERSAL ACCESS, INC., an Illinois
corporation with its principal place of business at 100 North Riverside Plaza,
Suite 2200, Chicago, Illinois 60606-1502 ("Customer").

For purposes of this Amendment, the rates, terms and conditions set forth herein
shall become effective on the first day of the next IXC billing cycle following
the last date of execution below (the "Amendment Effective Date").

This Amendment is made with reference to the following facts:

        A.      Customer and Supplier are parties to that certain Master Service
Agreement dated as of November 6, 1997 and subsequent Amendment No. 1 dated
March 23, 1999 (as amended, the "Agreement").

        B.      The parties desire to amend the Agreement pursuant to the terms
set forth below.

                               TERMS OF AMENDMENT

Accordingly, in consideration of the mutual promises set forth below, the
parties agree as follows:

        1.      Section 8, Notices, of the Master Service Agreement Terms &
Conditions shall be modified as follows:

        8.      NOTICES. All notices and other communications hereunder shall be
                in writing and shall be deemed to have been duly given as of the
                date of delivery, facsimile transmission or mailing, and if
                mailed, first class postage prepaid, certified or registered
                mail, return receipt requested to the following persons, unless
                contrary instructions are given by the parties in writing:

                If to Supplier: IXC Communications Services, Inc.
                                1122 Capital of Texas Hwy. South
                                Austin, Texas 78746-6426
                                Attention: Contract Administration

               If to Customer:  Universal Access, Inc.
                                100 North Riverside Plaza, Suite 2200
                                Chicago, Illinois 60606-1502
                                Attention: Robert J. Pommer, COO

        2.      Exhibit D, Private Line Pricing, shall be replaced in its
entirety by Exhibit D, Private Line Pricing, attached hereto.

        3.      All other terms and conditions, provisions, supplements and
exhibits of the Agreement shall remain in full force and effect.

                         [SIGNATURE LINES ON NEXT PAGE]

<PAGE>   2

IN WITNESS WHEREOF, the parties have executed this Amendment as of the date last
written below.

IXC COMMUNICATIONS SERVICES, INC.       UNIVERSAL ACCESS, INC.

BY: /s/ LEO WEISH                       BY: /s/ ROBERT J. POMMER
   ---------------------------------       -------------------------------------

NAME: LEO WEISH                         NAME: Robert J. Pommer
     -------------------------------         -----------------------------------

TITLE: PRES-WHOLESALE                   TITLE: Chief Operating Officer
      ------------------------------          ----------------------------------

DATE: 7/19/99                           DATE: 7/1/99
     -------------------------------         -----------------------------------

<TABLE>
<S>                                                       <C>
FULL BUSINESS ADDRESS:                                    FULL BUSINESS ADDRESS:
1122 CAPITAL OF TEXAS HWY. SOUTH                          100 NORTH RIVERSIDE PLAZA, SUITE 2200
AUSTIN, TEXAS 78746-6426         Approved as to form      CHICAGO, ILLINOIS 60606-1502
TELEPHONE: (512) 427-3700            Legal dept.          TELEPHONE: (312) 660-5000
FACSIMILE: (512) 328-7902                                 FACSIMILE: (312) 660-5050
                                                          BILLING CONTACT: ACCOUNTS PAYABLE
                                                          TELEPHONE: (312) 660-5000
</TABLE>

                             AMENDMENT NO. 2 TO MSA

<PAGE>   3

EXHIBIT D - PRIVATE LINE PRICING
--------------------------------

<TABLE>
<CAPTION>
                                           RATE PER   V&H DS-0  MILE/CIRCUIT  LEASE TERM
SERVICE TYPE      MONTHLY VOLUME            1 YEAR    2 YEARS      3 YEARS      4 YEARS    5 YEARS
------------      --------------           --------   --------  ------------  ----------   -------
<S>               <C>                      <C>        <C>       <C>           <C>          <C>
DS-0              N/A                       [***]     [***]     [***]         [***]        [***]

DS-1              [***]                     [***]     [***]     [***]         [***]        [***]
                  [***]

DS-3              [***]                     [***]     [***]     [***]         [***]        [***]
                  [***]

OC-3              [***]                     [***]     [***]     [***]         [***]        [***]
                  [***]

OC-12             [***]                     [***]     [***]     [***]         [***]        [***]
                  [***]

OC-48             [***]                     [***]     [***]     [***]         [***]        [***]

MINIMUM CIRCUIT CHARGES:

                             DS-0                  [***]
                             DS-1                  [***]
                             DS-3                  [***]
                             OC-3                  [***]
                             OC-12                 [***]
                             OC-48                 [***]

MINIMUM CIRCUIT TERM:        1 Year
</TABLE>

NOTES:

1.      ALL PRIVATE LINE SERVICE TO CITIES NOT LISTED ON EXHIBIT C WILL BE
        PRICED ON AN INDIVIDUAL CASE BASIS AND WILL BE SUBJECT TO THE TERMS OF
        THE UNDERLYING CARRIER.

2.      EXISTING CIRCUITS MAY BE RE-RATED AT THE [***] MONTHLY VOLUME RATES
        PROVIDED (A) CUSTOMER REACHES AND MAINTAINS [***] IN INVOICED MONTHLY
        VOLUME AND (B) CUSTOMER SUBMITS A NEW MARKET SERVICE ORDER FOR EACH
        CIRCUIT TO BE RE-RATED WITH A NEW CIRCUIT LEASE TERM.

          AMENDMENT NO. 2 TO MSA PRIVATE LINE SERVICES EXHIBIT - PAGE 7

*** Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.<PAGE>   1
                                                                  EXHIBIT 10.19

                           CARRIER SERVICES AGREEMENT
                                  (MULTIMEDIA)

                                                         AGREEMENT NO.98R0613.00

This Carrier Services Agreement (this "Agreement") is made this 29th day of
June, 1998, by and between Williams Communications, Inc. d/b/a Williams Network
Services, a Delaware corporation ("Seller"), with its principal place of
business at One Williams Center, 26th Floor, Tulsa, Oklahoma 74172 and Universal
Access, Inc., an Illinois corporation ("Customer"), with its principal place of
business at 1021 Adams Street, Suite 101, Chicago, Illinois 60607, for the
provision of multimedia telecommunications services, set forth in this
Agreement.

1.0.     SCHEDULES.

The Schedules attached to this Agreement and made a part hereof are:

Schedule A - Williams Network Services Asynchronous Transfer Mode Service
Schedule including Pricing and Specifications

Schedule B - Williams Network Services Private Line Service Schedule including
Pricing and Specifications

Schedule C - List of Seller's On-Net Cities

2.0.     DESCRIPTION OF SERVICES AND PRICING.

Customer may order from Seller multimedia transmission services ("Services"),
the terms and conditions of which and the charges for which are set forth in
Seller's currently prevailing Multimedia Transmission Service Schedule relating
to such Services (the "Service Schedule"). Current Service Schedules are
attached to this Agreement, labeled as consecutive Schedules and incorporated
herein by this reference. Seller offers such Services, as defined in the
applicable Service Schedule, upon the terms and conditions set forth in the
Service Schedule, this Agreement, and any applicable tariff (the "Tariff") filed
by Seller with the Federal Communications Commission. The terms and conditions
of this Agreement (including the Schedules) are subject to change in accordance
with and to the extent of any changes made in such Tariff, if applicable, or as
such changes are generally applicable to Seller's other customers ordering
similar services, provided, however in no event shall the cost of On-Net IXC
Services be increased from current levels for the remainder of the term of this
Agreement. All Services and "Ancillary Services," as defined in Section 5.3, are
subject to availability.

3.0      EFFECTIVE DATE AND TERM

3.1      This Agreement shall become effective on the date on which Seller signs
the Agreement ("Effective Date").

3.2       The duration of this Agreement shall continue for a term of ten (10)
years (the "Initial Term") from the date by which Customer must meet its Revenue
Commitment (as defined below). This Agreement shall thereafter automatically
renew for successive five-year periods (each, a "Renewal Term") unless canceled
by either party by giving written notice of such cancellation not less than
sixty (60) days before the end of the Initial Term or any Renewal Term. Unless
Customer is in Default, any Service being provided at the time of termination
shall continue until the natural end of such Service as specified in the
applicable Service Schedule upon the terms and conditions of this Agreement;
provided that Customer may not order any new Service without first renewing this

                                  Page 1 of 24

<PAGE>   2

Agreement. The charges for Services and Ancillary Services during any such
extension shall be the then current Seller charges provided, however in no event
shall the cost of On-Net IXC Services be increased from current levels for the
remainder of the term of this Agreement. To the extent Seller (a) files a Tariff
incorporating a reduction in the price applicable to any Service or Ancillary
Service being provided to Customer under this Agreement or any Service Schedule,
or (b) reduces its standard list price for any Service or Ancillary Service for
such Service being provided to Customer under this Agreement or any Service
Schedule, then Seller shall reduce the prices charged to Customer
proportionately with respect to any such Service or Ancillary Service as of the
date of filing of such Tariff or reduction of such standard list price, as the
case may be (i.e. a retail price reduction of 10% would constitute a 10% price
reduction on existing rates for Customer on the services effected.)

3.3     Commencing twelve (12) months after the calendar month including the
Effective Date, Customer shall be obligated to have signed orders for on-network
Services in the amount of two hundred fifty thousand dollars ($250,000.00) in
total aggregate monthly billings (the "Revenue Commitment"). For the first [***]
months, Customer will receive the discounted rate associated with the [***]
revenue level. If, after the [***] month, Customer reaches [***]in monthly
revenues, it will receive the discounted rate associated with the [***] revenue
level. If Customer reaches [***] in monthly revenues by month [***], it will
receive the discounted rate associated with the [***]revenue level. If Customer
reaches [***] in monthly revenues by month [***] or at the month thereafter,
Customer will receive the discounted rate associated with the [***] and over
revenue level. If any of the above revenue levels are achieved, Customer will be
billed at the discounted rate associated with the revenue level they have
achieved. All charges for Services in this Agreement shall be determined in
accordance with the pricing set forth in the Service Schedules attached hereto
or on Customer's Service Orders, as applicable, inclusive of any discounts
applicable to Customer, but exclusive of any credits to which Customer may be
entitled, late payment penalties, taxes and other government-imposed surcharges.
Customer's purchases of Services shall also not include payments made by
Customer to Seller to reimburse Seller for third party costs paid to
unaffiliated entities, including, but not limited to, local access charges,
taxes, installation charges, off-network charges, one-time fees and other
similar costs. To the extent that, in any month during the Initial Term hereof,
Customer fails to have signed orders or a total aggregate billing of applicable
Services from Seller greater than or equal to the Revenue Commitment amount,
Williams shall invoice Customer on Customer's next invoice, an amount equal to
the difference between the Revenue Commitment amount and the amount of Services
actually purchased or committed to by order by Customer. For purposes of this
entire agreement, "on-network" means interexchange service provided by Seller on
facilities owned by Seller and bounded by Seller points of presence or services
that are ordered and scheduled to be Seller owned facilities within a one year
period from the date of order. (i.e. Customer will receive On-Net pricing at the
time of the order provided that the Seller has indicated that the route will be
On-Net within 12 months of the order.) At the time that the Off-Net circuit is
available for On-net use, Customer agrees to convert circuit to On-net
facilities at the first mutually acceptable date and time.

4.0      SERVICE ORDERS.

Services requested by Customer hereunder shall be requested on Seller's Service
Order forms in effect from time to time or on Customer's forms accepted in
writing by Seller ("Service Orders"). Each Service Order shall reference this
Agreement and its respective Agreement number. Seller reserves the right not to
accept a Service Order under this Agreement at any time.

When a Service Order is placed, the Customer will indicate a requested start
date (A Requested Start Date). Seller will make reasonable efforts to meet the
Requested Start Date. In the event that a Requested Start Date is altered, the
actual Start Date will be changed to reflect the number of days of delay or
advance, as appropriate.

This Agreement shall apply to all Services and Ancillary Services provided by
Seller to the Customer whether

*** Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                  Page 2 of 24

<PAGE>   3

pursuant to a Service Order or otherwise.

Any conflicting, different or additional terms and conditions contained in
Customer's acknowledgment or Service Order or elsewhere are objected to by
Seller and shall not constitute part of this Agreement. No action by Seller
(including, without limitation, provision of Services or Ancillary Services to
Customer pursuant to such Service Order) shall be construed as binding or
estopping Seller with respect to such term or condition, unless the Service
Order containing said specific term or condition has been signed by an
authorized headquarters representative of Seller.

Seller shall make reasonable efforts to provide Services within its standard
service implementation interval or on Customer's requested Start Date. Services
shall begin on the date Seller issues notice that service is available (the
"Start of Service Notice or (SOSN), indicating the service has been tested by
Seller in accordance with Seller's standard specifications and that the service
meets or exceeds those specifications.

Customer may request a delay in the Start Date of an order, a move, or
rearrangement when Seller receives delay request a minimum of fifteen (15) days
prior to the due date and the requested delay does not extend beyond (30)
cumulative days from the Service Orders initial Start Date. When Customer has
delayed a Service Order for the maximum thirty (30) cumulative calendar days,
the order may not be delayed again by Customer. Once the maximum thirty (30)
day delay has been achieved, Customer has the option to (a) accept the billing
for the Service Order, or (b) cancel the Service Order and pay the applicable
cancellation charges for the facilities ordered. The billing or cancellation is
effective on the 30th cumulative calendar of the delay. If Customer elects to
accept billing, the installation will be completed as soon as reasonably
practical after Customer advises Seller that the installation can be completed.

5.0.     LOCAL ACCESS AND ANCILLARY SERVICES.

5.1.     Seller shall, on behalf and upon request of Customer, obtain
telecommunications facilities connecting Customer, with an approved vendor of
Seller, to a Seller Point of Presence (POP). Customer will execute a Letter of
Agency, on such form as provided by Seller, authorizing Seller to interact
directly with the provider(s) of these access telecommunications facilities.
When Seller acts as Customers agent, Customer is responsible for charges
including without limitation, monthly charges, usage charges, installation
charges, non-recurring charges, or applicable termination/cancellation
liabilities, of the provider(s) of telecommunications facilities to Seller POPs.

5.2.     In doing so, Seller shall be responsible for provisioning and the
initial testing of an interconnection (reasonably coordinated with Start of
Service) between such interexchange service set forth in the Service Order and
a Customer designated termination point ("Local Access"). Charges to Customer
for Local Access Service administered on behalf of Customer by Seller shall not
exceed charges Customer would otherwise pay the same Local Access Provider for
the relevant interconnection and/or service. Should Customer be able to provide
Seller with a quote for the same Local Access service from the Same Local
Access Provider, Seller agrees to match quote for such service.

5.3.     Seller may also provide other extraordinary service to Customer for
reasons including but not limited to: (a) Customer's request to expedite
Service availability to a date earlier than Seller's published installation
interval or a previously accepted Start Date; (b) Service redesign or other
activity occasioned by receipt of inaccurate information from Customer; (c)
reinstallation charges following any suspension of the Service for cause by
Seller; (d) Customer's request for use of routes or facilities other than those
selected by Seller for provision of the Service; and (e) other circumstances in
which extraordinary costs and expenses are generated by Customer and reasonably
incurred by Seller (services under this subsection 5.3 are collectively
referred to herein as ("Ancillary Services").

5.4.     Recurring and non-recurring charges to Customer for Local and
Ancillary Services shall be established as of Seller's acceptance of the
Service Order relevant thereto. RECURRING CHARGES FOR LOCAL ACCESS BILLING
ADMINISTERED BY SELLER AND CHARGED TO CUSTOMER SHALL BE SUBJECT TO ADJUSTMENT
AT SUCH TIMES AS SELLER SHALL DETERMINE, NOT TO EXCEED THE PREVAILING CHARGES
OF SUCH LOCAL ACCESS PROVIDERS AS WOULD OTHERWISE BE PAID DIRECTLY BY CUSTOMER
FOR THE RELEVANT INTERCONNECTION OR SERVICE.

                                  Page 3 of 24

<PAGE>   4
6.0.     CHANGES IN SERVICE PARAMETERS.

6.1.     Cancellation of Services. Customer may cancel any Service or Ancillary
Service provided hereunder by providing written notification to Seller thereof
ninety 90) days in advance of the effective date of cancellation. In the event
of such cancellation, Customer shall not be required to pay to Seller a
cancellation charge as long as the circuit has been in service for at least
twelve (12) months, Customer's Revenue Commitment is still being met the
cancellation, and as long as Customer pays to Seller all termination liability
and one-time charges for local access or off-net, third party provided
facilities that are impacted by the cancellation. Customer shall also not be
required to pay to Seller a cancellation charge (except as set forth in Section
6.2 below) if Customer exercises the portability option defined in Section 6.2.
In the event the cancellation of the Service or Ancillary Service causes
Customer's monthly purchase of Services to fall below the Revenue Commitment
amount, Customer agrees to pay, the monthly difference between the Committed
Revenue amount and the amount actually billed until such time as Customer's
orders or billings exceed this Committed Revenue amount, and (ii) any
non-recurring payments not yet paid together with any termination liability
associated with Local Access. Customer agrees that the actual damages in the
event of such cancellation would be difficult or impossible to ascertain, and
that the cancellation charge in this Section 6.1 is intended, therefore, to
establish liquidated damages and is not intended as a penalty. Notwithstanding
the foregoing, and upon thirty (30) day's prior written notice to the other
party, either Customer or Seller shall have the right, without cancellation
charge or other liability to the other party, to cancel the affected portion of
any Service or Ancillary Service, if Seller is prohibited by governmental
authority from furnishing or Customer is prohibited from using such portion, or
if any material rate or term contained herein and relevant to the affected
portion of any Service or Ancillary Service is substantially changed by order of
the highest court of competent jurisdiction to adjudicate the matter, the
Federal Communications Commission, or other local, state or federal government
authority.

6.2      Portability. After any Service or Ancillary Service has been in effect
for a period of at least twelve (12) months, Customer shall have the option to
disconnect a circuit and turn up a new circuit as a replacement without
incurring a termination liability charge. The replacement circuit must be for
the same or greater term and the same or greater revenue as the circuit being
replaced. Should Customer exercise this portability option, Customer will be
liable for (i) all termination liability charges for local access or off-net,
third party provided facilities that are impacted by the move of the circuit;
and (ii) for all disconnect and one-time charges due to Seller under Seller's
standard disconnect and new installation rates and charges; and (iii) any
one-time local access charges and the new monthly recurring local access
charges. All circuits shall have portability within all areas served by Seller
on its network, subject to available capacity.

6.3      Service Migration. If Customer wishes to upgrade to a higher bandwidth
of service, Customer has forty-five (45) days from the turnup of the higher
bandwidth circuit in which to groom existing circuits onto the higher bandwidth
of service. During this forty-five (45) day period, the Customer will not be
billed for the higher bandwidth. After the forty-five (45) day period from
circuit turnup, billing for the higher bandwidth circuit commences, whether or
not if the existing circuits have been disconnected and groomed onto the larger
bandwidth.

7.0.     PAYMENT TERMS.

7.1.     Due Date and Invoice. All amounts stated on each monthly invoice are
due and payable thirty (30) days from the date of the invoice ("Due Date")
subject to postponement of disputed charges until resolution thereof as set
forth

                                  Page 4 of 24

<PAGE>   5

below. Customer agrees to remit payment to Seller at the remittance address. In
the event Customer fails to make full payment to the proper address by the Due
Date, Customer shall also pay a late fee in the amount of the lesser of one and
one-half percent (1 1/2) of the unpaid balance per month or the maximum lawful
rate under applicable state law which shall accrue from the Due Date. Customer
acknowledges and understands that all charges are computed exclusive of any
applicable federal, state or local use, excise, valued added, gross receipts,
sales and privilege taxes, duties, fees or similar liabilities (other than
general income or property taxes imposed on Seller), whether charged to or
against Seller, its suppliers or affiliates or Customer associated with the
Service or Ancillary Service provided to Customer ("Additional Charges"). Such
Additional Charges shall be paid by Customer in addition to all other charges
provided for herein.

Payment for all prorated monthly recurring charges (charges for monthly Service
or Ancillary Service provided for less than a calendar month), installation and
other non-recurring charges shall be billed following the receipt of any such
Services or Ancillary Service. Payment for all monthly recurring charges for
full months during which Service or Ancillary Service are to be provided shall
be due in advance.

If Customer in good faith disputes any portion of an invoice it must pay the
undisputed amount of the invoice on or before its Due Date and provide written
notice to Seller of the billing dispute within sixty (60) days thereafter. Such
notice must include documentation substantiating the dispute. Customer's failure
to notify Seller, of a dispute shall be deemed to be Customer's acceptance of
such charges. The parties will make a good faith effort to resolve billing
disputes as expeditiously as possible. If a dispute is resolved in favor of
Customer, Customer shall receive a credit on their next bill for the amount
determined to be due, if not, the additional sum due shall be payable no later
than 30 days following a dermination that it is due.

7.2.     Suspension of Service. In the event payment in full is not received
from Customer on or before sixty (60) days following the Due Date, Seller shall
have the right, after giving Customer ten (10) days notice, to suspend all or
any portion of the Services or Ancillary Service to Customer. If only a portion
of the Services or Ancillary Service are suspended and Customer does not cure
within ten days of delivery of notice of such partial suspension of Service,
Seller may suspend all or any additional portion of the Services or Ancillary
Service to Customer. Seller may continue suspension until such time as Customer
has paid in full all charges then due, including any late fees as specified
herein. Following such payment, Seller shall be required to reinstitute Service
or Ancillary Service to Customer only on the provision by Customer of
satisfactory assurance, in Seller's sole discretion which shall not be
unreasonably exercised of Customer's ability to pay for Service or Ancillary
Service. If Customer fails to provide such satisfactory assurance by a date
determined by and acceptable to Seller, Customer shall be deemed to have
canceled the Services or Ancillary Service provided under this Agreement
effective on the date of such suspension and shall remain liable for all
cancellation charges as set forth in Section 6.1. Further, if at any time there
is a material adverse change in Customer's creditworthiness or a material change
in Customer's financial position, then in addition to any other remedies
available to Seller, Seller may elect, in its sole discretion, to exercise one
or more of the following remedies: (i) cause the start of the Service or
Ancillary Service described in a previously executed Service Order to be
withheld; (ii) cease providing Service pursuant to a notice of suspension; (iii)
decline to accept a Service Order or other requests from Customer to provide
Service or Ancillary Service which Seller may otherwise be obligated to accept;
and/or (iv) condition its provision of Service or Ancillary Service or
acceptance of a Service Order on Customer's assurance of payment which shall be
a deposit or such other means to establish reasonable assurance of payment. An
adverse material change in Customer's creditworthiness shall include, but not be
limited to: (a) Customer's default of its financial obligations to Seller under
this or any other agreement with Seller; which default remains uncured. (b)
failure of Customer to make full payment of charges due hereunder on or before
the Due Date on three (3) or more occasions during any period of twelve (12) or
fewer months or Customer's failure to make such payment on or before the Due
Date in any two (2) consecutive months; (c) acquisition of Customer (whether in
whole or by majority or controlling interest) by an entity which is insolvent,
which is subject to bankruptcy or insolvency proceedings, which owes past due
amounts to Seller or any entity affiliated with Seller or which is a materially
greater credit risk than Customer; or, (d)

                                  Page 5 of 24

<PAGE>   6

Customer having filed for bankruptcy or insolvency proceedings or an involuntary
petition for Bankruptcy has been filed against Customer which has not been
deismissed within 60 days of the initial filing date. An adverse material change
in Customer's financial position shall include, but not be limited to: (a) a
decrease in net worth or working capital of five percent (5%) or greater; or,
(b) negative net worth or working capital. If Customer's financial statements
are not public information, Customer shall be required to provide financial
statements upon the request of Seller and Seller agrees hereby to hold such
financial statements in strict confidence subject only to the right to use such
financial statements for the purposes of this Agreement.

7.3.     Taxes. If any sales taxes, valued added taxes or similar charges or
impositions are asserted against Seller after, or as a result of, Customer's use
of Services or Ancillary Service by any local, state, national, international,
public or quasi-public governmental entity or foreign government or its
political subdivision, including without limitation, any tax or charge levied to
support the Universal Service Fund contemplated by the Telecommunications Act of
1996, Customer shall be solely responsible for such taxes, charges or
impositions. Customer agrees to pay any such taxes, charges or impositions and
hold Seller harmless from any liability or expense associated with such taxes,
charges or impositions.

7.4      Adjustments. Seller may make billing adjustments for a period of two
(2) years after the Due Date of an invoice, or two (2) years after the date a
service is rendered, whichever is later.

8.0.     GENERAL AGREEMENT.

8.1.     Warranty and Disclaimer of Warranty. Seller warrants that Services or
Ancillary Service shall be provided to Customer in accordance with the technical
parameters set forth in the applicable Service Schedule. Seller shall use
commercially reasonable efforts under the circumstances to remedy any delays,
interruptions, omissions, mistakes, accidents or errors in the Services or
Ancillary Service and restore such Services or Ancillary Service to comply with
the terms hereof. THE FOREGOING WARRANTY AND THE OUTAGE CREDITS REMEDY PROVIDED
TO CUSTOMER AS SET FORTH IN THE APPLICABLE SERVICE SCHEDULE FOR THE FAILURE TO
COMPLY WITH THIS WARRANTY ARE EXCLUSIVE AND IN LIEU OF ALL OTHER WARRANTIES OR
REMEDIES, WHETHER EXPRESS, IMPLIED OR STATUTORY, INCLUDING WITHOUT LIMITATION,
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.

8.2.     Limitation of Liability. IN THE EVENT OF ANY BREACH OF THIS AGREEMENT
OR ANY FAILURE OF THE SERVICES OR THE ANCILLARY SERVICES, WHATSOEVER, NO
PROVIDER (AS DEFINED IN SECTION 8.3) SHALL BE LIABLE FOR ANY DIRECT, INDIRECT,
CONSEQUENTIAL, SPECIAL, ACTUAL, INCIDENTAL, PUNITIVE OR ANY OTHER DAMAGES, OR
FOR ANY LOST PROFITS OF ANY KIND OR NATURE WHATSOEVER.

NEITHER CUSTOMER NOR ANY PROVIDER SHALL BE LIABLE TO THE OTHER FOR ANY
CONSEQUENTIAL, SPECIAL, INCIDENTAL, PUNITIVE OR ANY OTHER SIMILAR DAMAGES, OR
FOR ANY LOST PROFITS OF ANY KIND OR NATURE WHATSOEVER WITH RESPECT TO THIS
AGREEMENT OR FOR THE LOSS OR FAILURE OF THE SERVICES OR THE ANCILLARY SERVICES.

8.3.     Customer Content and Indemnity. Customer shall make all arrangements
with copyright holders, music licensing organizations, performers'
representatives or other parties for necessary authorizations, clearances or
consents with respect to transmission contents ("Consents"). Customer shall
indemnify and hold harmless Seller and any third party or affiliated provider,
operator or maintenance/repair contractor of facilities employed in connection
with the provision of Services or Ancillary Service (all of which shall be
referred to as "Providers")

                                  Page 6 of 24

<PAGE>   7

against and from any court, administrative or agency action, suit or similar
proceeding, whether civil or criminal, private or public, brought against
Providers arising out of or related to the contents transmitted hereunder (over
Seller's network or otherwise) including, but not limited to, claims, actual or
alleged, relating to any violation of copyright law, export control laws,
failure to procure Consents, failure to meet governmental or other technical
broadcast standards, or that such transmission contents are libelous,
slanderous, an invasion of privacy, pornographic, or otherwise unauthorized or
illegal. Seller may terminate or restrict any transmissions over the network if,
in its judgment, (a) such actions are reasonably appropriate to avoid violation
of applicable law; or (b) there is a reasonable risk that criminal, civil or
administrative proceedings or investigations based upon the transmission
contents shall be instituted against Providers. Customer agrees not to use
Services or Ancillary Service for any unlawful purpose, including without
limitation any use which constitutes or may constitute a violation of any local,
state or federal obscenity law.

8.4.     a) Customer and Seller shall, indemnify and hold harmless the other
against and from any and all claims for physical property damage, physical
personal injury or wrongful death to the extent that such arises out of the
negligence or willful misconduct of the respective indemnifying party, its
employees, agents, or contractors in connection with the provision of Services,
Ancillary Services or other performance.

         b) With respect to third parties that use Services or Ancillary Service
through Customer, Customer shall, indemnify and hold harmless Providers against
any claims by such third parties for damages arising or resulting from any
defect in or failure to provide Services or Ancillary Service.

         c) Customer shall, indemnify and hold harmless Providers for any breach
of Customer's obligations under Section 8.3.

         d) The indemnifying party agrees to defend the other against the claims
as set forth above and to pay all reasonable litigation costs, attorneys' fees,
court costs, settlement payments, and any damages awarded or resulting from any
such claims. The indemnified party shall promptly notify the indemnifying party
in writing of any such claims and tender the defense thereto.

8.5.     Force Majeure. If either party's performance of this Agreement or any
obligation (other than the obligation to make payments) hereunder is prevented,
restricted or interfered with by causes beyond its reasonable control including,
but not limited to, acts of God, fire, explosion, vandalism, cable cut, power
outage, storm or other similar occurrence including rain fade or other
atmospheric conditions, any law, order, regulation, direction, action or request
of the United States Government or state or local governments, or of any
department, agency, commission, court, bureau, corporation or other
instrumentality of any one or more said governments, or of any civil or military
authority, or by national emergencies, insurrections, riots, wars, acts of
terrorism, strikes, lockouts or work stoppages or other labor difficulties,
supplier failures, shortages, breaches or delays, then the affected party shall
be excused from such performance on a day-to-day basis to the extent of such
prevention, restriction or interference. The affected party shall use
commercially reasonable efforts under the circumstances to avoid and remove such
causes of non-performance and shall proceed to perform with reasonable dispatch
whenever such causes cease.

8.6.     Events of Default. If the quality of transmission provided under such
Service or Ancillary Service falls below the level of quality set forth in the
technical parameters applicable to such Service or Ancillary Service set forth
in the applicable Schedule, then Customer may terminate that Service or
Ancillary Service, provided that written notice is given to Seller setting forth
the specifics of a default and provided that Seller is unable to cure such
quality default within five (5) days after notice of the default is received by
Seller.

Either party may terminate this Agreement if the other is in default of any
material obligation contained herein, which default has not been cured within
fifteen (15) days following the receipt of notice of such default setting

                                  Page 7 of 24

<PAGE>   8

forth the specifics of such default. Customer may terminate this Agreement if
Seller is unable to provide operational circuits for at least 90% of the
circuits Customer has contracted for for at least 48 hours and such outage
continues as of the date of serving notice of termination by Customer then
Customer may immediately terminate this Agreement without penalty. Termination
and receipt of any applicable refund are Customer's remedies in the event of any
such Seller's default.

8.7.     Use of Services. Seller's obligation to provide Services or Ancillary
Service to Customer is subject to the following conditions: (a) Services or
Ancillary Service shall not be used for any unlawful purpose, (b) Services may
be used only for multimedia transmissions (i.e., video and radio transmission
services and/or related applications including, but not limited to, graphic,
visual, imaging, interactive and multimedia), and (c) at least ten percent (10%)
of the transmissions shall be interstate transmissions. Customer represents that
this Agreement, to the extent it is subject to FCC regulation, is an
inter-carrier agreement not subject to the filing requirements of Section 211(a)
of the Communications Act of 1934, as amended.

8.8.     Proprietary Information. Customer understands and agrees that the terms
and conditions of this Agreement and all documents referenced herein (including
invoices to Customer for Services or Ancillary Service provided hereunder) are
confidential as between Customer, Seller and its affiliates and shall not be
disclosed by Customer to any party other than the directors, officers, and
employees of Customer or agent's of Customer who have specifically agreed to
nondisclosure of the terms and conditions hereof. Violation by Customer or its
agents of the foregoing provision shall entitle Seller, at its option, to
discontinue Services or Ancillary Service to Customer without further obligation
or liability to Customer. Customer further agrees that any Customer generated
press release, advertisement or publication regarding this Agreement, Services
or Ancillary Service provided hereunder or in which Seller, or its affiliates
are to be mentioned, will be submitted to Seller for its written approval prior
to publication. Customer understands and agrees that Seller may disclose such
information as may be required under applicable law including, without
limitation, filing of tariffs.

8.9.     Intrastate Interexchange Services. Customer may use any interexchange
Service provided under this Agreement only if such interexchange Service is used
for carrying interstate telecommunications (i.e., telecommunications subject to
the jurisdiction of the Federal Communications Commission). Seller and its
affiliates shall not be obligated to make available interexchange Service on a
circuit with end points within a single state or service on a circuit which
originates/terminates at points both of which are situated within a single state
unless Customer represents in writing that such interexchange Service or
circuits shall be used to carry interstate telecommunications. If it is
determined at any time that such interexchange Service or circuit is subject to
state regulation, the interexchange Service or circuit may be provided by Seller
or its affiliates pursuant to applicable state laws, regulations and applicable
tariffs, or Seller and its affiliates may discontinue provision of the affected
interexchange Service or circuit.

8.10.    Customer Responsibilities. Customer has sole responsibility for
installation, testing and operation facilities, services and equipment
("Customer Facilities") other than those specifically provided by Seller as part
the Service or Ancillary Service as described in a Service Order. In no event
will the untimely installation or ?? operation of Customer Facilities relieve
Customer of its obligation to pay charges for the Service or Ancillary Service
after the start of Services as set forth in the Service Order.

9.0.     MISCELLANEOUS PROVISIONS.

9.1.     Title to Equipment. This Agreement shall not, and shall not be deemed
to, convey from Seller to Customer title of any kind to any of the transmission
facilities, digital encoder/decoders, telephone lines, microwave facilities or
other facilities utilized in connection with the Services or Ancillary Service.
Any equipment provided by Customer must be itemized on a schedule listing all
such Customer-provided equipment and appended to the Service Order to which use
of that equipment relates ("Customer Equipment Inventory"). Seller shall not be

                                  Page 8 of 24

<PAGE>   9

obligated to provide any Services or Ancillary Service for Customer if Customer
will be providing any of its own equipment unless and until such equipment is
itemized on the applicable Customer Equipment Inventory.

9.2.     Notice. All notices to be sent to a party pursuant to this Agreement
shall be in writing and deemed to be effective upon (i) personal delivery, (ii)
three days after mailing certified mail return receipt requested, (iii) on the
day when the notice has been telexed or telecopied if during business hours and
followed by express mail priority next-day delivery, or (iv) in the case of
invoices, upon the Due Date. In each case, the notice shall be sent to the
person identified in this Section at the Full Business Addresses of the parties
as they appear herein. The effective date for any notice under this Agreement
shall be the date of delivery of such notice, not the date of mailing.

The Full Business Address for purposes of notice under this Section as well as
telephone voice and facsimile numbers for reservation of services and
troubleshooting shall be:

One Williams Center, 26th Floor
Tulsa, Oklahoma 74172
Telephone: (918) 588-5760
Fax: (918) 561-6578
Attention: Contract Administration

CUSTOMER:            Universal Access, Inc.
                     1021 Adams Street, Suite 101
                     Chicago, Illinois 60607
                     Telephone: (312)491-1700
                     Fax: (312) 421-9006
                     Attn: Robert J. Pommer

9.3.     Merger/Integration. This Agreement (including the attached Schedules,
as they may be modified from time to time) consists of all the terms and
conditions contained herein and in documents incorporated herein specifically by
reference. This Agreement constitutes the complete and exclusive statement of
the understanding between the parties and supersedes all proposals and prior
agreements (oral or written) between the parties relating to Services or
Ancillary Service provided hereunder.

9.4.     Written Amendment. Customer agrees that any addition, deletion or
modification to this Agreement shall not be binding on Seller except by written
agreement executed by Seller and Customer.

9.5.     No Venture. The provision of Services or Ancillary Service shall not
create a partnership or joint venture between the parties.

9.6.     Conflict of Law. In addition to the nonpayment of any sum due
hereunder, Seller may immediately suspend Services or Ancillary Service in whole
or part if Seller determines that such Services or Ancillary Service violate the
Communications Act of 1934, as amended (including the Telecommunications Act of
1996), or that the imposition of any state or federal statute, or promulgation
of any rule, regulation, or order of the Federal Communications Commission
("FCC") or other governing body makes Seller's performance commercially
impracticable.

9.7.     Assignment. Customer shall not assign or otherwise transfer (including
without limitation, a transfer due to a "Change of Control") its rights or
obligations under this Agreement without the prior written consent of Seller,
which shall not be unreasonably withheld. Any such assignment or transfer of
Customer's rights or obligations without such consent shall entitle Seller to
terminate the Services or Ancillary Service provided hereunder at its

                                  Page 9 of 24

<PAGE>   10

option upon ten (10) days' prior written notice to Customer. A "Change in
Control" shall be deemed to be an assignment, merger, sale of a controlling
interest or other transfer of a controlling ownership interest provided that if
Customer engages in an initial (or any subsequent) public offering of its equity
securities, none of such offering shall be deemed to constitute a "Change in
Control" for the purposes of this Agreement. In the case of a merger, sale or
change or transfer of controlling interest, Should Seller withhold assignment of
contract, Customer has the right to terminate this agreement. In the event that
Universal Access becomes insolvent, Seller agrees to consider a direct
relationship with Universal Access's end customers prior to disconnection
subject to normal credit and approval processes.

9.8.     Choice of Law. This Agreement shall be governed by the laws of the
State of Oklahoma without regard to choice of law principles. Customer hereby
consents to the jurisdiction of the federal and state courts having a situs in
Tulsa County, Oklahoma over any proceeding initiated with respect to the
enforcement or interpretation of this Agreement.

9.9.     Interpretation. No rule of construction requiring interpretation
against the draftsman hereof shall apply in the interpretation of this
Agreement.

9.10.    No Third Party Beneficiary. The provisions of this Agreement are for
the benefit only of the parties hereto, and no third party may seek to enforce
or benefit from these provisions.

9.11.    Attorneys' Fees. If a proceeding is brought for the enforcement of this
Agreement or because of any alleged or actual dispute, breach, default or
misrepresentation in connection with any of the provisions of this Agreement,
the prevailing party shall be entitled to recover reasonable attorneys' fees and
other costs and expenses incurred in such action or proceeding in addition to
any other relief to which such party may be entitled.

9.12.    Severability. In the event any provision of this Agreement conflicts
with any statute, rule or order of any governmental unit or regulatory body, or
tariff then, if required by law, such statute, rule, order or tariff shall
control.

9.13.    No Waiver. The failure of either party to enforce any provision hereof
in whole or in part, shall not constitute the permanent waiver of such
provision.

UNIVERSAL ACCESS, INC.                      WILLIAMS COMMUNICATIONS, INC.

AN ILLINOIS CORPORATION.                    A DELAWARE CORPORATION

By: /s/ ROBERT J. POMMER                    By: /s/ GORDON C. MARTIN
Name: Robert J. Pommer                      Name: Gordon C. Martin
      ---------------------------                 ---------------------------

Title: Chief Operating Officer              Title: Vice President,
       --------------------------                  --------------------------
                                                   Sales, Marketing
                                                  ---------------------------

Date: 7/14/98                               Date: 7/21/98
      ---------------                             ---------------

                                  Page 10 of 24

<PAGE>   11

Schedule A

              Williams Network Asynchronous Transfer Mode ServiceTM

                               SERVICES & PRICING

This Asynchronous Transfer Mode Service Schedule ("ATMSS") is made as of this
__21st__ day of __May ______, 1998__, and is subject to that Carrier Services
Agreement No. _____________ (the "CSA") by and between Williams Communications,
Inc. d/b/a Williams Network Services, a Delaware corporation ("Williams"), and
Universal Access, Inc., an __ Illinois______________ corporation ("Customer").

1.       DESCRIPTION: Williams Network Asynchronous. Transfer Mode (ATM) is
         multi-service technology that provides integration of disparate
         networks onto a single communications infrastructure. ATM technology
         takes voice, data and video packets and divides them into equally
         sized, 53-byte cells and transmits them over the Williams Network ATM
         network. Williams Network ATM service is designed for two (2) primary
         applications. These applications include ATM transport and backbone
         connectivity. ATM transport provides multimedia aggregation and video
         transmission. Multimedia transmission is suited for transporting voice,
         data and video while video transmission is best designed for
         point-to-point video services. Backbone connectivity provides for the
         interconnection of local area networks (LANs) as well as
         interconnection of existing Network Access Points (NAPs) or private
         peering backbones.

2.       RATES & CHARGES: Williams Network ATM service has three basic rate
         elements; Access, Port Connections, and either Committed Bit Rate
         (CBR), or Variable Bit Rate (VBR) Permanent Virtual Circuits (PVCs) and
         Virtual Paths (VPs).

         2.1      Permanent virtual circuit (PVC) and Virtual Path (VP)
                  bandwidth charges. PVC and VP charges are based on the class
                  of service (CoS) and bandwidth selected. Bandwidth charges are
                  stated in Committed Information Rates (CIR) or Megabit per
                  second (Mbps) increments for one-way, or Simplex PVCs. CIR
                  increments are available in 1Meg increments up to 40Mbps for
                  DS3 ports, 5 Meg increments up to 150 Mpbs for OC3 ports and
                  25 Meg increments up to 600 Mbps for OC12 ports. Two Classes
                  of Service are offered; Constant Bit Rate (CBR) and Variable
                  Bit Rate non real time (VBRnrt). Monthly recurring charges for
                  port, PVCs and VPs are as follows:

2.1.1    ATM SERVICES

PRICING

ATM Transport includes both Recurring and Non-Recurring charges and discounts
based on term and monthly revenue commitment.

RECURRING CHARGES

ATM pricing is based on flat monthly fee assessed per node, which includes a
flat port charge based on the port connection speed, a charge for each PVCs CIR
going out from the port, and local access. ATM Transport Service is priced
simplex, meaning that a PVCs CIR is priced for both the ingress and egress CIR.

                                  Page 11 of 24

<PAGE>   12

CIRS INCREMENTS ARE AVAILABLE IN 1MEG INCREMENTS UP TO 40MBPS FOR DS3 PORTS, 5
MEG INCREMENTS UP TO 150 MPBS FOR OC3 PORTS AND 25 MEG INCREMENTS UP TO 600 MBPS
FOR OC12 PORTS (OC12 IS ICB ONLY).

<TABLE>
<CAPTION>
                                                                <?>
                   <?>           <?>                  <?>               <?>                  <?>
<S>                             <C>                  <C>               <C>                  <C>
                                 20-29                [***]             VBRnrt               [***]
                                 30-40                [***]             VBRnrt               [***]
                    OC3          5-20                 [***]             VBRnrt               [***]
                                 25-35                [***]             VBRnrt               [***]
                                 40-55                [***]             VBRnrt               [***]
                                 60-75                [***]             VBRnrt               [***]
                                 80-95                [***]             VBRnrt               [***]
                                 100-120              [***]             VBRnrt               [***]
                                 125-150              [***]             VBRnrt               [***]

                    DS3          1-9                  [***]             CBR                  [***]
                                 10-19                [***]             CBR                  [***]
                                 20-29                [***]             CBR                  [***]
                                 30-40                [***]             CBR                  [***]
                    OC3          5-20                 [***]             CBR                  [***]
                                 25-35                [***]             CBR                  [***]
                                 40-55                [***]             CBR                  [***]
                                 60-75                [***]             CBR                  [***]
                                 80-95                [***]             CBR                  [***]
                                 100-120              [***]             CBR                  [***]
                                 125-150              [***]             CBR                  [***]
</TABLE>

*** Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                  Page 12 of 24

<PAGE>   13

NON RECURRING CHARGES

Non-recurring charges include installation, configuration changes, cancellation,
order change that may be incurred for the Port or PVC.

<TABLE>
<CAPTION>
                                           <?>
                   <?>                                           <?>
<S>                                                             <C>
                   Installation

                   45Mb Port                                     [***]
                   155Mb Port                                    [***]
                   622Mb Port                                    [***]
                   per PVC                                       [***]

                   Ancillary

                   Configuration Changes                         [***]
                   Cancellation                                  [***]
                   PVC Order Change                              [***]
                   Port Order Change                             [***]
</TABLE>

DISCOUNT STRUCTURE

Contributing Williams Network ATM Service charges include recurring port and PVC
charges. The discount structure is based on the monthly revenue commitment
(contributing charges) and the stated length of the contract established.

Discount Structure

<TABLE>
<CAPTION>
Monthly          1 Year            2 Year          3 Year           4 Year            5 Year
Revenue
<S>              <C>              <C>              <C>              <C>              <C>
$   0               0%               0%               0%               0%               0%

[***]              12%              14%              18%              22%              27%

[***]              14%              16%              20%              24%              29%

[***]              16%              18%              22%              26%              31%

[***]              18%              20%              24%              28%              33%

[***]              20%              22%              26%              30%              35%
</TABLE>

PARENT/SUBSIDIARY RELATIONSHIPS. If parent/subsidiary billing is provided, all
subsidiaries will contribute toward the overall commitment. The same discount,
based on the revenue commitment will apply for all subsidiary accounts.

CROSS PRODUCT DISCOUNTING. Revenue commitment levels are transferable to any of
the products in the product suite. For example, a private line revenue
commitment of $50,000 for 1 Year term can be used to determine the discount
applied for ATM services for the same term ($50,000 1 Year commitment would
equate to a.14% discount).

2.1.2    Non-recurring PVC and VP charges:  Installation: -[***]

2.1.3                                       Configuration Changes -[***]

2.1.4                                       Cancellation Charge -[***]

*** Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                  Page 13 of 24

<PAGE>   14

         For on-net, IXC Services, installation and non-recurrning charges shall
         be waived by Seller at the time of order. Should an individual on-net,
         IXC circuit cancel prior to the eighteen month anniversary of its
         installation, Seller will back bill Customer the full installation and
         non-recurring amount fo?? circuit.

         Configuration charges are applied when the parameters of Virtual
         Channels (VCs) are changed.

         Cancellation Charges apply when a PVC has been ordered and needs to be
         canceled.

2.2      Ports. Port charges are based on port speed connections selected.
         Options currently are DS3, OC3 and OC12. Port charges are as follows:

2.2.1    Non-recurring charges:      DS3 Port Installation -[***]

                                     OC3 Port Installation -[***]

                                     OC12 Port Installation -[***]

                                     Port Order Change Charge: -[***]

                                     Port Cancellation Charge:  -[***]

         Port Order Change Charges apply when the customer requests to change
         the port size ordered. If the Port has been installed and accepted, the
         customer will be charged for a new port installation.

         Port Cancellation Charges apply when a port has been ordered (does not
         apply for ports installed and accepted) and needs to be canceled.

2.3      Local Access Charges. Local Access Charges are based on the cost of
         transmission capacity provided by Customer or a third party supplier
         to extend the Services provided by Williams from a Williams Point of
         Presence to any other location ("Local Access Services"). Williams
         shall use reasonable efforts to order Local Access services on behalf
         of Customer, provided that Customer provides Williams with a letter of
         agency. Where available, and if requested by Customer, Williams will
         use reasonable efforts to use Customer's requested Local Access
         provider. If Williams places an order for Customer for Local Access
         Services, Williams will bill Customer for such services and Customer
         shall hold harmless and indemnify Williams from any loss or liability
         incurred by Williams as a result of Williams ordering any such Local
         Access Services from a third party. Customer may, upon Williams' prior
         written approval, order its own local access services. If Customer
         orders its own Local Access Services, Customer shall be billed
         directly by the supplier of such services and Williams shall not be
         responsible for billing any such charges.

3.       OFF-NET SERVICES PRICING: All services provided to Customer which are
         not on network facilities owned by Williams will be priced on an
         individual case basis at the time Customer requests such service.

4.       OUTAGE CREDITS:

4.1      Customer acknowledges the possibility of an unscheduled, continuous
         and/or interrupted period of time when a Service or Services are
         "UNAVAILABLE" (as defined in the Specifications) for a continuous
         period of two (2) hours (hereafter an "OUTAGE"). An Outage shall begin
         upon recognition by Williams that the Service is interrupted. In the
         event of an Outage, Customer shall be entitled to a credit (the "OUTAGE
         CREDIT") in the amount of ten percent (10%) of the monthly Port, PVC
         and/or usage charges (as stated on the applicable Service Order)
         regardless of the length of such Outage.

4.2      Customer shall not receive an Outage Credit if the interruptions are
         (a) of a duration of less than tw??

*** Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                  Page 14 of 24

<PAGE>   15

         consecutive hours, (b) caused by the negligence or willful misconduct
         of Customer or others authorized by Customer to use the services under
         this Agreement, (c) due to the failure of power, facilities, equipment,
         systems or connection not provided by Seller, (d) caused by the failure
         of access to Seller's fiber optic network, (e) resultant from scheduled
         maintenance where Customer has been notified of scheduled maintenance
         in advance, (f) due to a Force Majeure event as defined in Section 8.5
         of the CSA.

4.3      All Outage Credits shall be credited on the next monthly invoice for
         the affected Service.

4.4      The Outage Credit described in this Section 4 of this ATMSS shall be
         the sole and exclusive remedy of Customer in the event of any Outage,
         and under no circumstance shall an outage be deemed a Default under
         this Agreement.

SIGNATURE PAGE TO FOLLOW

                                  Page 15 of 24

<PAGE>   16

IN WITNESS WHEREOF, the parties hereto have executed this Asynchronous Transfer
Mode Service Schedule as of the day and year first above written.

UNIVERSAL ACCESS, INC.                    WILLIAMS COMMUNICATIONS, INC:

/s/ Signature Illegible                   /s/ Signature Illegible
Signature of Authorized                   Signature of Authorized
Representative                            Representative

Robert J. Pommer                          Gordon C. Martin
--------------------------------          --------------------------------
Printed Name                              Printed Name

Chief Operating Officer                   Vice President, Sales, Marketing
--------------------------------          --------------------------------
Title                                     Title

                                  Page 16 of 24

<PAGE>   17

               Williams Network Asynchronous Transfer Mode Service

                            Technical Specifications

1.0      Definition. Williams Network technical specifications are stated as an
         objective that the ATM network will perform in accordance with
         prevailing telecommunications industry standards. Williams Network will
         use reasonable efforts to remedy delays, interruptions, omissions or
         mistakes within the ATM network.

1.1      Performance Objectives. All service provided under the Williams Network
         Asynchronous Transfer Mode Service are measured using two variables:
         Network availability and Mean-time-to-repair.

1.2      Network Availability is a measurement of actual service time to stated
         service time. Network Availability objective: -99.99%

1.3      MTTR is the average time required to restore service and resume
         availability and is stated in terms of equipment and cable outages. The
         time is measured from the moment the outage is reported until the
         service is available and applies specifically to equipment outages or
         failures.

         MTTR objective:      -2 Hours (Equipment)

                              -6 Hours (First Fibers on Cable)

1.4      Calculation. Williams Network calculates network availability on
         customer action requests. The customer must notify Williams Network
         Customer Care Department and initiate an action request to determine if
         service level variables 1.2 & 1.3 were met.

                                  Page 17 of 24

<PAGE>   18

Schedule B

                      Williams Network Private Line Service

                               SERVICES & PRICING

This Private Line Service Schedule ("PLSS") is made as of this_21st __ day of
___ May ________, 1998, and is subject to that Carrier Services Agreement No.
____________ (the "CSA") by and between Williams Communications, Inc. d/b/a
Williams Network Services, a Delaware corporation ("Williams"), and Universal
Access, Inc., an _ Illinois _ corporation ("Customer").

1.       Description: Williams Network Private Line Service (the "Private Line
         Service" or "Service") provides domestic DS-3 and optical SONET (OC-N)
         circuits which are specifically dedicated to Customer's use between two
         (2) points specified by the Parties in a Service Order and meeting the
         technical requirements defined in the "Technical Specifications for
         Private Line Service" attached hereto.

2.       RATES & CHARGES: Williams Network Private Line Service has three basic
         rate elements; IXC Charges, Local Access Charges, and Non-recurring
         Charges.

2.1      IXC. DS-3 and OC-3 Services will be provided at the following rates for
         on-net services only:

<TABLE>
<CAPTION>
TIME FRAME                 MONTHLY COMMITMENT          DS3                OC3                OC12
<S>                               <C>                <C>                <C>                 <C>
YEAR 1                             [***]              [***]              [***]              [***]
YEAR 2 OR AS ACHIEVED              [***]              [***]              [***]              [***]
YEAR 3 OR AS ACHIEVED              [***]              [***]              [***]              [***]
YEAR 4 OR AS ACHIEVED              [***]              [***]              [***]              [***]
YEAR 5 OR AS ACHIEVED              [***]              [***]              [***]              [***]
</TABLE>

         Monthly minimum charges for Private Line Service:
         DS3s - [***]
         OC3s - [***]
         OC12s - [***]
         OC48s - [***]

         All other IXC rates will be determined on an individual case basis and
will be set forth on the Service Order.

2.2      Local Access Charges. Local Access Charges are based on the cost of
         transmission capacity provided by Customer or a third party supplier to
         extend the Services provided by Williams from a Williams Point of
         Presence to any other location ("Local Access Services"). Williams
         shall use reasonable efforts to order Local Access services on behalf
         of Customer, provided that Customer provides Williams with a letter of
         agency. Where available, and if requested by Customer, Williams will
         use reasonable efforts to use Customer's requested Local Access
         provider. If Williams places an order for Customer for Local Access
         Services, Williams will bill Customer for such services and Customer
         shall hold harmless and indemnify Williams from any loss or liability
         incurred by Williams as a result of Williams ordering any such Local
         Access Services from a third party. Customer may, upon Williams' prior
         written approval order its own local access services. If Customer
         orders its own Local Access Services, Customer shall be billed directly
         by the supplier of such services and Williams shall not be responsible
         for billing any such charges.

2.3      Non-recurring charges:

         DS-3       OC-3       OC-3C       OC-12       OC-12C       OC-48

*** Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

                                  Page 18 of 24

<PAGE>   19

<TABLE>
<S>                    <C>              <C>               <C>               <C>               <C>               <C>
Installation           [***]             [***]             [***]             [***]             [***]             [***]
Additional
Installation/          [***]/hr.         [***]/hr.         [***]/hr.         [***]/hr.         [***]/hr.         [***]/hr.
Maintenance/
Engineering
After hours            [***]/hr.         [***]/hr.         [***]/hr.         [***]/hr.         [***]/hr.         [***]/hr.
Local Loop
Billing                [***]             [***]             [***]             [***]             [***]             [***]
Administration
</TABLE>

[***] Additional Installation charges shall apply when Williams is required to
install equipment other than that normally required to provide the service or
when Customer requests special equipment. The above non-recurring charges are
subject to change, upon thirty (30) days prior written notice from Williams to
Customer.

3.       TERM OF SERVICES:

3.1      Upon acceptance of a Service Order, Williams shall confirm Customer's
         requested Start Date, or inform Customer of the estimated date for the
         delivery of each service. Williams shall use reasonable efforts to
         install each such service on or before the Start Date, but the
         inability of Williams to deliver a facility by such date shall not be a
         Default under this Agreement. If Williams fails to make any facility
         available within thirty (30) days after the Start Date, Customer's sole
         remedy shall be to cancel the Service Order which pertains to such
         Service by ten (10) calendar days prior written notice to Williams.

3.2      The effective date of each service (the "Service Effective Date") shall
         begin on the date on which Customer accepts delivery of such Service.
         If Customer fails to give written notice that the Service is in
         material non-compliance with the applicable technical specifications,
         as modified from time to time by Williams (the "Specifications") within
         fifteen (15) business days after notification to Customer by Williams
         that the Service is available, Customer shall be deemed to have
         accepted such Service, and the Service Effective Date shall commence as
         of the fifteenth (15th) business day following such notification by
         Williams. Following notice by Customer of material non-compliance as
         set forth above, Williams shall promptly take such reasonable action as
         is necessary to correct any such non-compliance in the Service and
         shall, upon correction, notify Customer of a new Service Effective
         Date.

4.       CHANGE OF SERVICES:

4.1      Change of Service Date. If Customer desires to change the date on which
         Customer has requested that Service be available, Customer may be
         charged a Change of Service Date Charge. Such charge will not apply to
         Customer's first change request, as long as such request is made within
         fifteen (15) business days prior to the original Requested Service
         Date. If Customer makes a second change, or such change is requested
         after fifteen (15) days prior to the original Requested Service Date,
         Customer will be charged Williams' then applicable Change of Service
         Date Charge. Customer will also be charged for any charges incurred by
         Williams from third party providers as a result of Customer's request
         for Change of Service Date.

4.2      Change of Service Order. If Customer requests a modification to the
         information contained in a Service Order (other than a Change of
         Service Date) prior to completion of installation of the Service,
         Customer will incur a Change of Service Order Charge. No charge will be
         incurred if the change is to the IXC part of the Service Order and is
         administrative in nature (i.e. billing address, contact information,
         etc.). A charge will be incurred if the administrative change relates
         to Local Access for which Williams is acting as agent.

         Change of Service Order charges will be lower if the Customer requests
         such change within five (5) business days after a Service Order has
         been accepted by Williams ("pre-engineering") and will be higher if
         such change is received after that time ("post-engineering"). Any
         expedited order will be considered to be in the post-engineering stage
         two (2) business days after the Service Order is accepted by Williams.

         *** Certain information on this page has been omitted and filed
         separately with the Commission. Confidential treatment has been
         requested with respect to the omitted portions.

                                  Page 19 of 24

<PAGE>   20

4.3      Change of Service Charges. If Customer requests a change to Services
         after such Services have been installed, Customer will incur a Change
         of Service Charge. If such Change of Service is administrative in
         nature, Customer will not incur a charge, unless such administrative
         change applies to Local Access services which have been ordered by
         Williams as agent for Customer. In addition to the Change of Service
         Charge, Customer will be responsible for any charges due to
         re-engineering which is required as a result of Customer's request for
         Change of Service.

5.       OFF-NET SERVICES PRICING: All services provided to Customer which are
         not on network facilities owned by Williams will be priced on an
         individual case basis at the time Customer requests such service.

6.       OUTAGE CREDITS:

6.1      Customer acknowledges the possibility of an unscheduled, continuous
         and/or interrupted period of time when a Service or Services are
         "UNAVAILABLE" (as defined in the Specifications) for a continuous
         period of two (2) hours (hereafter an "OUTAGE"). An Outage shall begin
         upon recognition by Williams that the Service is interrupted. In the
         event of an Outage, Customer shall be entitled to a credit (the "OUTAGE
         CREDIT") at the rate of 1/720 of the monthly recurring charge for the
         IXC portion of the circuit for each hour in excess of the first two (2)
         consecutive hours that the affected service fails to conform to the
         Specifications.

6.2      Customer shall not receive an Outage Credit if the interruptions are
         (a) of a duration of less than two (2) consecutive hours, (b) caused by
         the negligence or willful misconduct of Customer or others authorized
         by Customer to use the services under this Agreement, (c) due to the
         failure of power, facilities, equipment, systems or connection not
         provided by Seller, (d) caused by the failure of access to Seller's
         fiber optic network, (e) resultant from scheduled maintenance where
         Customer has been notified of scheduled maintenance in advance, (f) due
         to a Force Majeure event as defined in Section 8.4 of the CSA.

6.3      All Outage Credits shall be credited on the next monthly invoice for
         the affected Service.

6.4      The Outage Credit described in this Section 6 of this PLSS shall be the
         sole and exclusive remedy of Customer in the event of any Outage, and
         under no circumstance shall an outage be deemed a Default under this
         Agreement.

                                  Page 20 of 24

<PAGE>   21

VILLIAM'S

                                                                         3/18/98

SCHEDULE C

TIER 1 CITY LIST (TO BE UPDATED AS NEEDED)

<TABLE>
<CAPTION>
CITY LOCATION                                PROJECTED IN-SERVICE DATE
----------------------------------------------------------------------
<S>                                                 <C>
ALBANY, NY                                           12/98
ATLANTA, GA                                           8/98
BATON ROUGE, LA                                      10/98
BOISE, ID                                             3/99
BIRMINGHAM, AL                                       10/98
BUFFALO, NY                                          12/98
CHARLOTTE, NC                                        10/98
CHICAGO, IL                                           6/98
CINCINNATI, OH                                        4/99
CLEVELAND, OH                                         9/98
COLORADO SPRINGS, CO                                 11/98
COLUMBUS, OH                                          3/99
DALLAS, TX                                            6/98
DAYTON, OH                                            2/99
DAYTONA BEACH, FL                                    12/98
FT. LAUDERDALE, FL                                   12/98
FORT MEYERS, FL                                       4/99
GREENSBORO, NC                                        9/98
HOUSTON, TX                                          10/98
INDIANAPOLIS, IN                                      8/98
JACKSON, MS                                          10/98
JACKSONVILLE, FL                                     12/98
KANSAS CITY, MO                                      10/98
LAS VEGAS, NV                                         8/98
LAS ANGELES, CA                                       8/98
MACON, GA                                             1/99
MELBOURNE, FL                                        12/98
MIAMI, FL                                            12/98
NEW ORLEANS, LA                                      10/98
NEW YORK, NY                                         10/98
OKLAHOMA CITY, OK                                    11/98
ORLANDO, FL                                           1/99
PHOENIX, AZ                                           1/99
PORTLAND, OR                                          3/99
RALEIGH, NC                                           9/98
RICHMOND, VA                                         10/98
ROCHESTER, NY                                        12/98
SPARTANBURG, SC                                       8/98
ST. LOUIS, MO                                         8/98
</TABLE>

                                  Page 21 of 24

<PAGE>   22

<TABLE>
<S>                                                  <C>
SYRACUSE, NY                                          2/99
TAMPA, FL                                             1/99
TULSA, OK                                             6/98
TUCSON, AZ                                            3/99
WASHINGTON, DC                                        8/98
WEST PALM BEACH, FL                                  12/98
</TABLE>

NEAR FUTURE TIER 1 CITIES

<TABLE>
<CAPTION>
CITY LOCATION                               PROJECTED IN-SERVICE DATE
---------------------------------------------------------------------
<S>                                                  <C>
BALTIMORE, MD                                         5/99
EL PASO, TX                                           6/99
NEWARK, NJ                                            5/99
PHILADELPHIA, PA                                      5/99
</TABLE>

SIGNATURE PAGES TO FOLLOW

                                  Page 22 of 24

<PAGE>   23

IN WITNESS WHEREOF, the parties hereto have executed this Private Line Service
Schedule as of the day and year first above written.

UNIVERSAL ACCESS, INC.:                   WILLIAMS COMMUNICATIONS, INC:

/s/ ROBERT J. POMMER                      /s/ GORDON C. MARTIN
Signature of Authorized                   Signature of Authorized
Representative                            Representative

Robert J. Pommer                          Gordon C. Martin
Printed Name                              Printed Name

Chief Operating Officer                   Vice President, Sales & Marketing
--------------------------------          --------------------------------
Title                                     Title

                                  Page 23 of 24

<PAGE>   24
                TECHNICAL SPECIFICATIONS FOR PRIVATE LINE SERVICE

1.0      Interconnection Specifications

1.1      DS-3. DS-3 service is provided in accordance with ANSI Standard T1.102
         (formerly AT&T Compatibility Bulletin 119) and Technical Reference
         54014'4. DS-3 Service operates at 44.736 Mbps.

1.2      Optical SONET Services (OC-N). Optical SONET Services are provided in
         accordance with ANSI Standard T1.105. OC-3 Service operates at 155.520
         Mbps and is configured with 3 separate STS-1 signaling paths. OC-3C
         Service operates at 155.520 Mbps and is configured with 1 STS-3C
         signaling path (or 3 concatenated STS-1 signaling paths). OC-12 Service
         operates at 622.080 Mbps with 12 separate STS-1 signaling paths. OC-12C
         Service operates at 622.080 Mbps with 1 STS-12C signaling path (or 4
         separate STS-3C signaling paths). OC-48 Service operates at 9953.280
         Mbps and is configured with 48 separate STS-1 signaling paths.

2.0      Quality Standards

2.1      General. DS-3 and Optical SONET Service standards apply on a one-way
         basis between the Customer Premises Network Interface Points ("CPNIP")
         which are connected to Local Access between which DS-3 and Optical
         SONET Interexchange Service is provided (CPNIP to CPNIP or End-to-End)
         and exclude nonperformance due to force majeure or planned
         interruptions for necessary maintenance purposes. The actual end-to-end
         availability and performance of DS-3 and Optical SONET Service may be
         affected by the Customer provided equipment, dependent upon the type
         and quality of Customer equipment used. (Customer provided Local Access
         may not meet these specifications.)

2.2      Availability. Availability is a measurement of the percent of total
         time that service is operative when measured over a 365 consecutive day
         (8760 hour) period. DS-3 and Optical SONET Service is considered
         inoperative when there has been a loss of signal or when two
         consecutive 15 second loop-back tests confirm the observation of any
         severely errored seconds or a bit error rate equal to or worse than 1 x
         10-3. The Local Access availability standards for DS-3 and Optical
         SONET Services are established by the Local Access Provider. For
         Services on the Williams network, availability shall be 99.99% from
         point-of-presence ("POP") to POP measured over a one year period. For
         Services not on the Williams network, the off-net provider will
         establish availability. For multi-media services, availability will be
         the same as established by WorldCom, Inc.

2.3      Performance (% Error Free Seconds, while Available). Performance is
         noted in Error Free Seconds (EFS) which are a measure of the percentage
         of total seconds when measured over a consecutive 24 hour period that
         do not contain bit errors. Performance shall be measured on a one-way
         basis using a Pseudo Random Bit Sequence test pattern as defined in
         CCITT Recommendation 0.151. The Error Free Seconds standards for the
         Local Access for DS-3 and Optical SONET Service is established by the
         Local Access Provider. For Services on the Williams network, Error Free
         Seconds shall be 99.5% from POP to POP measured over a monthly period.
         For Services not on the Williams network, the off-net provider will
         establish Error Free Seconds. For multi-media services, Error Free
         Seconds will be as defined by WorldCom, Inc.

3.0      Maintenance

         Repair efforts will be undertaken upon notification of trouble by
         internal network surveillance and network surveillance and performance
         systems or by notification of trouble and release of all or part of the
         DS-3 or Optical SONET Service by the Customer for testing.

                  *        Mean Time to Restore (MTTR) is the average time
                           required to restore service and resume availability
                           and is stated in terms of equipment and cable
                           outages. The time is measured from the moment the
                           outage is reported until the service is available and
                           applies specifically to equipment outages or
                           failures.

                  *        MTTR objective:    -2 Hours (Equipment)
                                              -6 Hours (Equipment)

4.0      Calculation. Williams Network calculates network availability on
         customer action requests. The customer must notify Williams Network
         customer Care Department and initiate an action request to determine if
         service level variables 1.2 & 1.3 were met.

                                  Page 24 of 24

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