Document:

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                                                                    EXHIBIT 10.9

                                 THIRD AMENDMENT
                                     TO THE
                            ALLEGIANCE TELECOM, INC.
                            1998 STOCK INCENTIVE PLAN

WHEREAS, the Allegiance Telecom, Inc. 1998 Stock Incentive Plan was adopted by
the Board of Directors of Allegiance Telecom, Inc. ("Allegiance").

WHEREAS, Allegiance's Board of Directors is amending the Allegiance Telecom,
Inc. 1998 Stock Incentive Plan in accordance with Section 16 of such plan.

RESOLVED, that the number of shares of common stock available under the
Allegiance Telecom, Inc. 1998 Stock Incentive Plan be increased by substituting
the number "24,000,000" for the number "15,233,667" in Section 4 of this plan
(which 24,000,000 number shall be the aggregate number of shares available under
the 1998 Stock Incentive Plan). Such amendment was approved by the Board of
Directors of Allegiance on November 2, 2000.

FURTHER RESOLVED, that the officers of Allegiance be, and hereby are, authorized
to take whatever actions are necessary to carry out the intent and purpose of
the foregoing amendment.

                                      E-III<PAGE>   1
                                                                   EXHIBIT 10.15
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NOTE: CERTAIN MATERIAL HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL
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                                     MASTER
                              PROCUREMENT AGREEMENT

                                 BY AND BETWEEN

                            ALLEGIANCE TELECOM, INC.

                                       AND

                            LUCENT TECHNOLOGIES INC.

                                 APRIL 28, 2000

                                  CONFIDENTIAL

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                                                                    CONFIDENTIAL

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* NOTE: CERTAIN MATERIAL HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL
TREATMENT AND SUCH MATERIAL HAS BEEN FILED SEPARATELY WITH THE SEC.

                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
ARTICLE                                                                              PAGE
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<S>               <C>                                                                <C>
ARTICLE 1  GENERAL..................................................................   1

         1.1      Procurement of Products...........................................   1
                  1.1.1    General..................................................   1
                  1.1.2    Product Addenda..........................................   1
                  1.1.3    Statements of Work.......................................   1
         1.2      Account Administration............................................   2
                  1.2.1    Lucent Official..........................................   2
                  1.2.2    Lucent Account Executive.................................   2
                  1.2.3    Lucent Project Manager...................................   3
         1.3      Status of Certain Existing Contracts..............................   3
         1.4      Special Terms Relating to Growth and Restructurings...............   3
                  1.4.1    Allegiance Growth and Restructurings.....................   3
                  1.4.2    Lucent Growth and Restructuring..........................   4
         1.5      Benefits of Agreement.............................................   4
         1.6      Restrictions on Product Use and Resale............................   4
         1.7      *        .........................................................   4
         1.8      Definitions.......................................................   5
         1.9      Conflicts in Interpretation.......................................   5

ARTICLE 2  ACQUISITION AND PROVISIONING PROCESS.....................................   5

         2.1      Product Addenda...................................................   5
                  2.1.1    Product Addenda for Switch Products......................   5
                  2.1.2    Product Addendum for IDLC Products.......................   6
                  2.1.3    Product Addendum for IAD Products........................   6
                  2.1.4    Product Addendum ConnectVu-ATP...........................   6
                  2.1.5    Development of Product Addenda...........................   6
                  2.1.6    Ordering Products Pursuant to Product Addenda............   7
                           2.1.6.1    Requests for Quote............................   7
                           2.1.6.2    Quotes........................................   7
                           2.1.6.3    Short-Form Quote..............................   8
                           2.1.6.4    Negotiation of Quote..........................   8
                           2.1.6.5    Purchase Orders for Switch Products...........   8
         2.2      Statements of Work  ..............................................   8
         2.3      Purchase Orders...................................................   8
         2.4      Delivery of Products..............................................   9
                  2.4.1    General..................................................   9
                  2.4.2    Bill-and-Hold Products...................................   9
                  2.4.3    Product Delivery Delays..................................   9
         2.5      Product Delivery Cancellations....................................   9
</TABLE>

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* NOTE: CERTAIN MATERIAL HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL
TREATMENT AND SUCH MATERIAL HAS BEEN FILED SEPARATELY WITH THE SEC.

<TABLE>
<CAPTION>
ARTICLE                                                                              PAGE
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<S>               <C>                                                                <C>
ARTICLE 3  SOFTWARE AND EQUIPMENT...................................................  10

         3.1      Software License..................................................  10
                  3.1.1    Grant of License.........................................  10
                  3.1.2    Optional Software Features...............................  10
                  3.1.3    Virtual Collocation......................................  10
                  3.1.4    Ownership Rights Reserved................................  11
                  3.1.5    Additional Licensing Terms...............................  11
         3.2      *        .........................................................  11
                  3.2.1    *........................................................  11
                  3.2.2    Access to Specifications for *, Data Models
                           and Similar Information..................................  11
                  3.2.3    Cooperation..............................................  11
         3.3      Custom Programming................................................  12
         3.4      *        .........................................................  12
                  3.4.1    *........................................................  12
                  3.4.2    *........................................................  12
                  3.4.3    *........................................................  12
         3.5      Transfer Rights...................................................  12
         3.6      Equipment.........................................................  13
                  3.6.1    Equipment and Equipment Configuration....................  13
                  3.6.2    CLEI Codes...............................................  13
                  3.6.3    Title, Risk of Loss; Payment Terms.......................  13
                  3.6.4    Substitutions............................................  13
                  3.6.5    Replacement Parts for Equipment and Related Firmware.....  14
                           3.6.5.1  Availability....................................  14
                           3.6.5.2  Third Party Parts...............................  14
                           3.6.5.3  Equipment Repair and/or Replacement.............  14
                           3.6.5.4  Reporting.......................................  15
                  3.6.6    Discontinuation of Products..............................  15
                  3.6.7    Site Preparation.........................................  15
         3.7      Compatible Products...............................................  15
         3.8      Purchase Orders and Shipment Reports..............................  15

ARTICLE 4  SERVICES ................................................................  16

         4.1      General  .........................................................  16
         4.2      Right to Access; Identification Credentials; Facility Rules.......  16
                  4.2.1    Right of Access..........................................  16
                  4.2.2    Identification Credentials...............................  16
                  4.2.3    Facility Rules...........................................  16
         4.3      Compliance with Local Employment/Labor Laws.......................  16
         4.4      License of Know-How...............................................  16
</TABLE>

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* NOTE: CERTAIN MATERIAL HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL
TREATMENT AND SUCH MATERIAL HAS BEEN FILED SEPARATELY WITH THE SEC.

<TABLE>
<CAPTION>
ARTICLE                                                                              PAGE
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<S>               <C>                                                                <C>
ARTICLE 5  ACCOUNT ADMINISTRATION, PROJECT
  MANAGEMENT AND PERSONNEL .........................................................  16

         5.1      General Account Administration....................................  16
                  5.1.1    Covenant of Cooperation..................................  16
                  5.1.2    Executive Briefings......................................  17
                  5.1.3    Review of Contractual Matters............................  17
         5.2      Lucent Cooperation with Consultants...............................  17
         5.3      Lucent Personnel..................................................  17
         5.4      Removal of Lucent Personnel by Allegiance.........................  18
         5.5      Removal/Reassignment of Lucent Personnel by Lucent................  18
         5.6      Allegiance Personnel..............................................  18
         5.7      Status Meetings and Reports.......................................  18
         5.8      Administration of Projects........................................  19

ARTICLE 6  INSTALLATION AND IMPLEMENTATION..........................................  19

         6.1      Implementation Workplan...........................................  19
         6.2      *        .........................................................  19
         6.3      Specifications and Performance Standards..........................  20
         6.4      Change Order Procedure............................................  20
         6.5      Conversions.......................................................  20
         6.6      Instruction and Training..........................................  20
                  6.6.1    General..................................................  20
                  6.6.2    * Training *.............................................  21
         6.7      Access to First Office Application and Broadcast Warning Message..  21

ARTICLE 7  TESTING AND ACCEPTANCE...................................................  21

         7.1      General  .........................................................  21
         7.2      Certification Testing.............................................  21
         7.3      Product Acceptance................................................  22
         7.4      Installation Testing..............................................  22
         7.5      Installation Acceptance/Project Acceptance........................  22
         7.6      Failure to Achieve Acceptance.....................................  23
         7.7      Post-Acceptance Correction of Defects.............................  23

ARTICLE 8  SUPPORT AND MAINTENANCE SERVICES.........................................  23

         8.1      General  .........................................................  23
         8.2      Term and Termination..............................................  23
         8.3      Third Party Product Support and Maintenance Services Guarantees...  23
         8.4      Support and Maintenance Services Fees.............................  24
         8.5      Warranty Periods..................................................  24
</TABLE>

                                      -iii-                         CONFIDENTIAL
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* NOTE: CERTAIN MATERIAL HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL
TREATMENT AND SUCH MATERIAL HAS BEEN FILED SEPARATELY WITH THE SEC.

<TABLE>
<CAPTION>
ARTICLE                                                                              PAGE
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<S>               <C>                                                                <C>
         8.6      Support and Maintenance Services Report...........................  24

ARTICLE 9  REPRESENTATIONS AND WARRANTIES...........................................  25

         9.1      Lucent Product Functionality Warranty.............................  25
         9.2      *        .........................................................  25
         9.3      Performance Warranties............................................  25
                  9.3.1    *........................................................  25
                  9.3.2    Compatibility Warranty for Products......................  25
                  9.3.3    *........................................................  25
         9.4      *        .........................................................  25
         9.5      Euro Warranty.....................................................  25
         9.6      *        .........................................................  26
         9.7      Third Party Warranties and Indemnities............................  26
         9.8      Services Warranty.................................................  26
         9.9      Intellectual Property Warranty....................................  26
         9.10     Warranty of Authority.............................................  26
         9.11     Warranty of Title.................................................  26
         9.12     Pending Litigation Warranty.......................................  27
         9.13     Additional Warranties.............................................  27
         9.14     Change of Control Warranty........................................  27
         9.15     Material Misstatements or Omissions...............................  27
         9.16     Warranty Disclaimer...............................................  27

ARTICLE 10  PRICING AND PAYMENT TERMS...............................................  27

         10.1     Time and Method of Payment........................................  27
                  10.1.1   Invoicing................................................  27
                  10.1.2   Payments.................................................  28
                  10.1.3   Electronic Funds Transfer................................  28
                  10.1.4   Invoicing for Products and Bill-and-Hold Products........  28
                  10.1.5   Invoicing for Software...................................  29
                  10.1.6   Invoicing for Services...................................  29
                           10.1.6.1   *.............................................  29
                           10.1.6.2   *.............................................  29
         10.2     *                   ..............................................  29
         10.3     Travel Policy, Out-of-Pocket Expenses and Other Charges...........  29
         10.4     Taxes    .........................................................  29
                  10.4.1   General..................................................  29
                  10.4.2   Special Provision Relating to State Sales and Use
                           Taxes....................................................  29
                  10.4.3   Special Provision Relating to Taxes on Products Sold
                           Outside the United States................................  30
                  10.4.4   Special Provision Relating to Taxes on Services
                           Provided Outside the United States.......................  30
</TABLE>

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* NOTE: CERTAIN MATERIAL HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL
TREATMENT AND SUCH MATERIAL HAS BEEN FILED SEPARATELY WITH THE SEC.

<TABLE>
<CAPTION>
ARTICLE                                                                              PAGE
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<S>               <C>                                                                <C>
         10.5     Customs Duties Drawbacks..........................................  30
         10.6     *        .........................................................  30
         10.7     Allegiance Purchase Commitment....................................  30
         10.8     *.................................................................  31
                  10.8.1   *........................................................  31
                  10.8.2   *........................................................  31

ARTICLE 11  TERM AND TERMINATION....................................................  31

         11.1     Term of Agreement.................................................  31
         11.2     Events of Default.................................................  31
         11.3     Rights and Remedies of Lucent Upon Default of Allegiance..........  33
         11.4     Rights and Remedies of Allegiance Upon Default of Lucent..........  33
                  11.4.1   General..................................................  33
                  11.4.2   Right to Set Off.........................................  34
                  11.4.3   Transition Rights........................................  34
         11.5     Attorneys' Fees...................................................  34
         11.6     Limitation of Liability...........................................  34
                  11.6.1   Limitation Upon Types of Recoverable Damages.............  34
                  11.6.2   Cap on Damages...........................................  34
                  11.6.3   Exclusions from Limitations of Liability.................  34
         11.7     Termination Without Cause.........................................  35

ARTICLE 12  PROPRIETARY RIGHTS, CONFIDENTIALITY
                  AND SECURITY......................................................  35

         12.1     Ownership of Intellectual Property................................  35
         12.2     Confidential Information..........................................  35
         12.3     Return of Confidential Information................................  36
         12.4     Notification Obligation...........................................  36
         12.5     Employee/Agent Acknowledgment.....................................  37
         12.6     Change of Employment..............................................  37
         12.7     Enforcement of Confidentiality Obligations........................  37
         12.8     Survival .........................................................  37

ARTICLE 13  INDEMNIFICATION AND INSURANCE...........................................  37

         13.1     General  .........................................................  37
         13.2     Proprietary Rights Infringement Indemnification...................  37
         13.3     Procedures for Indemnification....................................  38
                  13.3.1   General..................................................  38
                  13.3.2   Defense Assumed..........................................  38
                  13.3.3   Defense Declined.........................................  38
                  13.3.4   Settlement of Claims.....................................  39
</TABLE>

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* NOTE: CERTAIN MATERIAL HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL
TREATMENT AND SUCH MATERIAL HAS BEEN FILED SEPARATELY WITH THE SEC.

<TABLE>
<CAPTION>
ARTICLE                                                                              PAGE
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<S>               <C>                                                                <C>
                  13.3.5   Contributory Negligence; Right of Contribution...........  39
         13.4     Survival; No Limitation of Liability..............................  39
         13.5     Insurance.........................................................  39

ARTICLE 14  DISPUTE RESOLUTION......................................................  39

         14.1     Project Manager Level Performance Review..........................  39
         14.2     Executive Level Performance Review................................  39
         14.3     Voluntary, Non-Binding Mediation..................................  40
         14.4     Continued Performance.............................................  40
         14.5     Equitable Relief..................................................  40

ARTICLE 15  MISCELLANEOUS  .........................................................  40

         15.1     Notices  .........................................................  40
         15.2     Bankruptcy........................................................  41
         15.3     Approval of Subcontractors........................................  41
         15.4     Force Majeure.....................................................  41
         15.5     Binding Nature and Assignment.....................................  41
         15.6     Media Releases and Public Disclosures of Agreement................  42
         15.7     Counterparts......................................................  42
         15.8     Severability......................................................  42
         15.9     Waiver   .........................................................  42
         15.10    Governing Law; Exclusive Jurisdiction.............................  42
         15.11    Compliance with Regulations.......................................  42
                  15.11.1    Radio Frequency Energy Standards.......................  42
                  15.11.2    Registration...........................................  43
                  15.11.3    Other..................................................  43
         15.12    No Construction Against Drafter...................................  43
         15.13    Relationship of Parties...........................................  43
         15.14    International Provisions..........................................  43
                  15.14.1    Compliance with Export Regulations.....................  43
                  15.14.2    Services Performed Outside the United States...........  43
                  15.14.3    U.S. Foreign Corrupt Practices Act and Other Laws......  44
                  15.14.4    Language Requirements..................................  44
         15.15    Entire Agreement; Modification....................................  44
</TABLE>

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* NOTE: CERTAIN MATERIAL HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL
TREATMENT AND SUCH MATERIAL HAS BEEN FILED SEPARATELY WITH THE SEC.

                       SCHEDULES, EXHIBITS AND ATTACHMENTS

<TABLE>

<S>                                     <C>
Schedule 1.8                            Defined Terms
Schedule 1.9                            Graphical Depiction of Order of Precedence
Schedule 2.1.1                          General Terms and Conditions Applicable to Product Addenda for
                                        Switch Products
Schedule 2.1.6.2                        Checklist for Developing Quotes
Schedule 2.2                            Checklist for Developing Product Addenda and Statements of Work
Schedule 4.4                            *
Schedule 5.7                            Sample Status Report
Schedule 7.1                            Products Subject to Installation Testing Only
Schedule 7.3                            Acceptance Certificate
  Attachment A to Acceptance
      Certificate                       Project, Equipment and/or Software
Schedule 8.1                            Support and Maintenance Services
  Attachment 1 to Schedule 8.1          Allegiance Account Team
  Attachment 2 to Schedule 8.1          Support Options for Lucent Products
  Attachment 3 to Schedule 8.1          Priority Personnel
Schedule 8.5                            Warranty Periods
Schedule 10                             Service Rates and Personnel Categories
Schedule 10.3                           Allegiance's Travel and Out-of-Pocket Expense Policy
Schedule 13.5                           Insurance Requirements

Exhibit 1                               Product Addenda and Statements of Work
                                        Product Addendum One (Switch Products)
                                        Product Addendum Two (IDLC Products)
                                        Product Addendum Three (IAD Products)
                                        Product Addendum Four (ConnectVu-ATP Products)
Exhibit 2                               *
Exhibit 3                               Virtual Collocation Software License Agreement
Exhibit 4                               First Amendment to Services Agreement
</TABLE>

                               -vii-                                CONFIDENTIAL

<PAGE>   9

                          MASTER PROCUREMENT AGREEMENT

         This Master Procurement Agreement ("AGREEMENT") is made and entered
into this 28th day of April, 2000 (the "EFFECTIVE DATE"), by and between
Allegiance Telecom, Inc., a Delaware corporation with a place of business at
1950 Stemmons Freeway, Suite 3026, Dallas, Texas 75207 ("ALLEGIANCE"), and
Lucent Technologies Inc., a Delaware corporation with a place of business at 600
Mountain Avenue, Murray Hill, New Jersey 07974 ("LUCENT").

                                    RECITALS:

         WHEREAS, Allegiance provides telecommunications products and services
to business, government and other institutional users, offering an integrated
set of telecommunications products and services including, without limitation,
local exchange, local access, domestic and international long distance, enhanced
voice, data and a full suite of Internet services.

         WHEREAS, Allegiance wants to purchase from Lucent, and Lucent wants to
supply Allegiance the Products and Services described herein, all in accordance
with the terms and conditions set forth in this Agreement.

         NOW, THEREFORE, in consideration of the mutual covenants and agreements
hereinafter set forth, and for other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, Allegiance and Lucent
agree to the foregoing and as follows:

                              ARTICLE 1 -- GENERAL

         1.1      PROCUREMENT OF PRODUCTS.

                  1.1.1 GENERAL. This Agreement represents the terms and
         conditions under which Lucent and its Affiliates shall provide Products
         and/or Services to Allegiance and its Affiliates on a global, worldwide
         basis pursuant to product purchase addenda (each, a "PRODUCT
         ADDENDUM"), Statements of Work and/or purchase orders that are signed
         and issued by an authorized representative of Allegiance and developed
         in accordance with the terms and conditions set forth in this SECTION
         1.1 and the acquisition and provisioning terms and conditions set forth
         in ARTICLE 2. The signatories to any Procurement Document may be
         Affiliates of either party that are located in the country in which the
         Products and/or Services that are the subject of such Procurement
         Document are to be installed and/or retained, as applicable. In
         principle, Products and Services will be contracted under the terms of
         this Agreement between local Affiliates of the parties, if such
         Affiliates are established in the country where the Products are to be
         provided or the Services are to be performed. All Product Addenda and
         Statements of Work will be attached and incorporated herein as part of
         EXHIBIT 1.

                  1.1.2 PRODUCT ADDENDA. For Products of the same type
         including, by way of example, Switch Products, the parties have or will
         develop Product Addenda that set forth, among other things, complete
         pricing information for such Products, all as further described in
         SECTION 2.1. Allegiance or the applicable Allegiance Affiliate shall
         have the right to acquire Products that are the subject of a Product
         Addendum by initiating the provisioning process set forth in SECTION
         2.1.6.

                  1.1.3 STATEMENTS OF WORK. For Products and/or Services that
         are unique or otherwise are not of the type that would be included in a
         Product Addendum including, by way of example,

<PAGE>   10

         Custom Programming Services, Allegiance or the applicable Allegiance
         Affiliate shall have the right to acquire such Services from Lucent
         pursuant to a Statement of Work developed in accordance with SECTION
         2.2.

         1.2      ACCOUNT ADMINISTRATION. In order to service Allegiance's
needs, Lucent shall appoint the following Lucent personnel to perform the duties
described below in this Section: a Lucent Vice President or higher-level officer
(the "LUCENT OFFICIAL"), a centralized Lucent contract coordinator and
administrator ("LUCENT ACCOUNT EXECUTIVE") and, as may be specified in the
applicable Procurement Document, a Lucent project manager (each, a "LUCENT
PROJECT MANAGER").

                  1.2.1 LUCENT OFFICIAL. The Lucent Official shall have full
         authority to contractually commit for, and make decisions with respect
         to, all Lucent matters as they relate to this Agreement. The Lucent
         Official shall attend all executive briefings as described in SECTION
         5.1.2. If, based on its experiences with the appointed Lucent Official,
         Allegiance believes that such individual is not authorized to make
         decisions for and on behalf of Lucent as described in this Section, at
         Allegiance's request, Lucent shall replace the Lucent Official with an
         individual that has the requisite authority as described in this
         Section.

                  1.2.2 LUCENT ACCOUNT EXECUTIVE. The Lucent Account Executive
         shall, among other things, administer the relationship between
         Allegiance and Lucent on a daily, weekly and monthly basis and act as a
         liaison between Lucent and Allegiance for all maters related to this
         Agreement and applicable Procurement Documents. The Lucent Account
         Executive shall have knowledge of the financial relationship between
         the parties as set forth in this Agreement and all Procurement
         Documents and shall have overall responsibility for ensuring Lucent's
         performance of all of its responsibilities and obligations as set forth
         therein. The Lucent Account Executive shall, among other things:

                           (a) Serve as the single point of contact at Lucent to
                  administer all aspects of this Agreement and all Procurement
                  Documents;

                           (b) Ensure that all policies and procedures relating
                  to Lucent's administration of this Agreement and all
                  Procurement Documents are applied consistently by Lucent and
                  all of its Affiliates;

                           (c) Coordinate the provisioning and acquisition
                  processes set forth in ARTICLE 2;

                           (d) Have working knowledge of the terms and status of
                  this Agreement, including all Procurement Documents;

                           (e) Coordinate and provide all reports required under
                  this Agreement including, without limitation, those reports
                  identified in SECTIONS 3.8, 5.7 and 8.6;

                           (f) Communicate to Lucent and all Lucent Affiliates
                  any Allegiance-specific technical considerations that may
                  impact multiple Procurement Documents;

                           (g) Attend all executive briefings and, when
                  requested by Allegiance, status meetings; and

                           (i) Ensure the performance of each Lucent Project
                  Manager.

                                -2-                                 CONFIDENTIAL

<PAGE>   11

         Allegiance shall appoint an Allegiance representative to serve as the
         counterpart to the Lucent Account Executive. Such Allegiance
         representative shall perform each of the roles and shall be responsible
         for each of the items enumerated in SUBSECTIONS (a) through (i) above
         to the extent such items are applicable to Allegiance.

                  1.2.3 LUCENT PROJECT MANAGER. Each Procurement Document may
         designate, as appropriate, a Lucent Project Manager for a given
         project. The Lucent Project Manager shall act as a liaison between
         Lucent and Allegiance for all matters related to the applicable
         Procurement Document and shall have overall responsibility for ensuring
         Lucent's performance of its responsibilities and obligations for a
         given project and/or as set forth in the applicable Procurement
         Document. If the parties agree not to designate a Lucent Project
         Manager for a particular Procurement Document, the Lucent Account
         Executive shall perform all of the duties of the Lucent Project Manager
         with respect to the such Procurement Document.

         1.3      STATUS OF CERTAIN EXISTING CONTRACTS.

                  (a) TERMINATION OF EXISTING CONTRACT. That certain General
         Agreement between Allegiance and Lucent dated October 16, 1997, and all
         amendments and addenda thereto (collectively, the "EXISTING CONTRACT"),
         shall terminate as of the Effective Date and have no further force or
         effect, and all Confidential Information disclosed by the parties
         thereunder shall be subject in all respects to the terms of this
         Agreement. Additionally, from and after the Effective Date, all
         Products and Services acquired by Allegiance pursuant to the Existing
         Contract shall be subject in all respects to the terms of this
         Agreement; provided, however, that the warranty period set forth in the
         Existing Contract shall be applicable to the Products and Services
         purchased thereunder.

                  (b) TERMINATION OF PROFESSIONAL SERVICES AGREEMENT. That
         certain Professional Services Agreement between Allegiance and Lucent
         dated March 23, 1998, and all amendments and addenda thereto, shall
         terminate as of the Effective Date and have no further force or effect,
         and all Confidential Information disclosed by the parties thereunder
         shall be subject in all respects to the terms of this Agreement.
         Additionally, from and after the Effective Date, all Services, if any,
         acquired by Allegiance pursuant to the Professional Services Agreement
         shall be subject in all respects to the terms of this Agreement.

                  (c) OCTEL CONTRACT. Concurrently with the execution of this
         Agreement, the parties have executed that certain First Amendment to
         Services Agreement attached hereto as EXHIBIT 4.

         1.4      SPECIAL TERMS RELATING TO GROWTH AND RESTRUCTURINGS.

                  1.4.1 ALLEGIANCE GROWTH AND RESTRUCTURINGS. If Allegiance
         acquires a new Affiliate following the Effective Date and such new
         Affiliate is a party to one (1) or more agreements with Lucent,
         Allegiance and/or such Affiliate shall have the right, upon written
         notice to Lucent, to terminate any and all existing agreements between
         such Affiliate and Lucent without liability or penalty, and all
         products and services acquired by such Affiliate from Lucent pursuant
         to such agreements thereafter shall be subject in all respects to the
         terms and conditions set forth in this Agreement. Notwithstanding the
         foregoing, if such existing agreements include purchase commitments or
         cover products and services for which a Product Addendum or Statement
         of Work is not then in effect under this Agreement, then the Lucent
         products and services acquired by such Allegiance Affiliate shall
         remain subject to the terms of the applicable existing agreements until
         such time as Allegiance and Lucent reach agreement with respect to the
         handling of such purchase

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         commitment and/or develop a mutually agreed Product Addendum or
         Statement of Work covering such products and services, as the case may
         be.

                  1.4.2 LUCENT GROWTH AND RESTRUCTURING. If Lucent acquires a
         new Affiliate following the Effective Date and such new Affiliate is a
         party to one (1) or more agreements with Allegiance, the products and
         services obtained and to be obtained by Allegiance pursuant to such
         agreements shall be subject in all respects to the terms of SECTIONS
         9.2, 9.4, 9.5, 9.8, 9.9, 9.11, 9.12, 9.16, 13.2 and ARTICLE 12 of this
         Agreement as though such products and services originally were provided
         to Allegiance pursuant to this Agreement, provided that such terms will
         be in addition to and not replacements of any similar terms contained
         in such agreements (provided, however, that if and to the extent there
         is a conflict between such provisions, the provisions contained in this
         Agreement shall apply), it being the intent of the parties that such
         terms of this Agreement shall supplement the terms of such agreements.
         At the request of Allegiance, Lucent shall negotiate in good faith new
         product functionality and performance warranties for such new Affiliate
         agreements of the nature set forth in SECTIONS 9.1 and 9.3 of this
         Agreement, and upon completion of such negotiations shall agree to an
         amendment to the terms of the Agreement. If Lucent integrates and/or
         migrates support and maintenance services for such products and
         services within Lucent's support and maintenance structure, Lucent
         shall provide Support and Maintenance Services for such products and
         services under the Support and Maintenance Services terms of this
         Agreement; provided, however, that in the event the support and
         maintenance terms under the existing new Affiliate agreement are more
         favorable than the Support and Maintenance Services terms under this
         Agreement, Allegiance shall have the right to continue the support and
         maintenance terms under such existing new Affiliate agreement. Upon the
         request of Allegiance, Lucent shall negotiate in good faith the
         termination or other disposition of a new Affiliate agreement based on
         the business needs of Allegiance.

         1.5      BENEFITS OF AGREEMENT. All rights and benefits granted
hereunder to Allegiance may be exercised and enjoyed by any Affiliate of
Allegiance, and Allegiance shall have the right to lease all Products purchased
under this Agreement to its Affiliates. References to Allegiance and to Lucent
in this Agreement shall include the parties' respective Affiliates, as
applicable and where the context so requires. Allegiance and Lucent shall be
responsible for ensuring each of their respective Affiliates' compliance with
their obligations hereunder including, without limitation, their compliance with
the terms of SECTIONS 15.14.1 and 15.14.3, and their compliance with the
confidentiality, licensing and payment obligations under this Agreement. For
purposes of calculating volume commitments and discounts (if any) available
under this Agreement that are based on volume, quantity or other measurement
factor, the total volume of Allegiance and all of its Affiliates shall be
considered to determine whether the applicable volume, quantity or other
measurement factor has been achieved.

         1.6      RESTRICTIONS ON PRODUCT USE AND RESALE. All Lucent Products
provided under this Agreement: (a) are intended for use in Allegiance's or its
Affiliates' business operations and will not be resold by Allegiance to Third
Parties unless Lucent has consented in writing to any such resale; provided,
however, that nothing contained in this Section shall be argued or construed to
constitute a restriction on the resale of used Products by Allegiance or any
Allegiance Affiliate or for purposes of providing resellers and other
communications companies with access to Allegiance's operations; and (b) shall
be used solely in accordance with the terms and conditions of this Agreement and
any applicable Procurement Document.

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* NOTE: CERTAIN MATERIAL HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL
TREATMENT AND SUCH MATERIAL HAS BEEN FILED SEPARATELY WITH THE SEC.

         1.7      *

         1.8      DEFINITIONS. Capitalized terms used herein shall have the
meanings ascribed to them in the body of this Agreement, in Procurement
Documents and/or in the Schedules, Exhibits, Attachments, Addenda and other
documents attached hereto, or as defined in SCHEDULE 1.8. Additional
project-specific definitions may be set forth in the applicable Procurement
Document.

         1.9      CONFLICTS IN INTERPRETATION. The following order of precedence
shall be followed in resolving any inconsistencies between the terms of this
Agreement and the terms of any Schedules, Exhibits, Attachments, Addenda and
other documents attached hereto: (a) first, the terms contained in the body of
this Agreement; (b) second, the terms of the Schedules, Exhibits, Attachments
and Addenda to this Agreement (excluding Procurement Documents attached hereto
as part of any Schedule, Exhibit, Attachment or Addendum which, for purposes of
precedent, shall be treated as set forth in SUBSECTION (c) below), provided that
no order of precedence shall be applied among such Schedules, Exhibits,
Attachments and Addenda; (c) third, the terms of any Product Addendum or
Statement of Work, including all Schedules, Exhibits, Attachments and Addenda
thereto (but excluding any Lucent responses to an Allegiance request for
proposal or request for information, which, for purposes of precedent, shall be
treated as set forth in SUBSECTION (E) below), provided that no order of
precedence shall be applied among such Product Addenda and Statements of Work;
(d) fourth, the terms of any purchase order signed and issued by an authorized
representative of Allegiance and accepted by Lucent, including all Schedules,
Exhibits, Attachments and Addenda thereto; (e) fifth, Lucent's response, if any,
to an Allegiance request for proposal or request for information, which response
shall be incorporated as part of the applicable Product Addendum or Statement of
Work by this reference unless otherwise set forth in the applicable Product
Addendum or Statement of Work; and (f) sixth, Documentation. The order of
precedence described herein is graphically depicted in the attached SCHEDULE
1.9. Any attempt to alter or amend the terms and conditions contained in the
Agreement through conflicting or inconsistent terms in a Procurement Document,
Schedule, Exhibit, Attachment, Addenda or any other document shall be void and
of no force and effect unless such conflicting or inconsistent terms
specifically are identified as an amendment to this Agreement and such amendment
is signed by an authorized representative of Allegiance as provided in SECTION
15.15, it being the parties' express understanding that any such alteration or
amendment shall require a formal amendment to this Agreement.

                ARTICLE 2 -- ACQUISITION AND PROVISIONING PROCESS

         2.1      PRODUCT ADDENDA. All Product Addenda shall be developed by the
parties in accordance with the terms set forth in SECTION 2.1.5 and shall
include, as applicable, the items set forth in SCHEDULE 2.2.

                  2.1.1 PRODUCT ADDENDA FOR SWITCH PRODUCTS. Each Product
         Addendum that relates to Switch Products shall be subject to the
         general terms and conditions applicable to Switch Products set forth in
         SCHEDULE 2.1.1. Attached hereto as part of EXHIBIT 1 is Product
         Addendum One (Switch Products), that sets forth terms and conditions
         applicable to Allegiance's purchase from Lucent of Switch Products for
         deployment in North America.

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* NOTE: CERTAIN MATERIAL HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL
TREATMENT AND SUCH MATERIAL HAS BEEN FILED SEPARATELY WITH THE SEC.

                  2.1.2 PRODUCT ADDENDUM FOR IDLC PRODUCTS. Attached hereto as
         part of EXHIBIT 1 is Product Addendum Two (IDLC Products), that sets
         forth terms and conditions applicable to Allegiance's purchase of IDLC
         Products from Lucent.

                  2.1.3 PRODUCT ADDENDUM FOR IAD PRODUCTS. Attached hereto as
         part of EXHIBIT 1 is Product Addendum Three (IAD Products), that sets
         forth terms and conditions applicable to Allegiance's purchase of
         integrated access Products from Lucent.

                  2.1.4 PRODUCT ADDENDUM FOR CONNECTVU-ATP. Attached hereto as
         part of EXHIBIT 1 is Product Addendum Four (ConnectVu-ATP), that sets
         forth terms and conditions applicable to Allegiance's purchase of
         ConnectVu-ATP Products from Lucent.

                  2.1.5 DEVELOPMENT OF PRODUCT ADDENDA. Allegiance and Lucent
         may mutually agree in writing following the Effective Date to develop
         and attach hereto Product Addenda. Each Product Addendum shall contain
         contract terms and conditions that are specific to the various types of
         Products and Services that Allegiance might acquire from Lucent under
         that Product Addendum, including terms and conditions that are legally
         required based on the countries in which such Products will be sold or
         installed and/or Services performed, including, without limitation,
         each of the following, as applicable:

                           (a) complete pricing information for the Product(s)
                  including, without limitation, all acquisition and/or
                  licensing costs associated with Software, Equipment, Support
                  and Maintenance Services, Enhancements, anticipated or
                  projected Equipment upgrade charges, and the like;

                           (b) a general Certification Test Plan and
                  Installation Test Plan for the Products (developed in
                  accordance with the terms set forth in ARTICLE 7);

                           (c) a general Implementation Workplan for the
                  Products;

                           (d) a list of countries in which the Product(s) are
                  homologated. Lucent shall notify Allegiance on a timely basis
                  and in writing of additional countries in which the Products
                  become homologated, or those countries in which the Products
                  are no longer homologated, and such notification shall be
                  attached to and become a part of the applicable Product
                  Addendum;

                           (e) a list of countries in which Lucent is authorized
                  to sell and/or install the Product(s). Lucent shall notify
                  Allegiance on a timely basis and in writing of additional
                  countries in which it is authorized to sell and/or install the
                  Products, or those countries in which Lucent is no longer
                  authorized to sell and/or install Products, and such
                  notification shall be attached to and become a part of the
                  applicable Product Addendum; and

                           (f) a list of standard * for the Products;

                           (g) with respect to Products that will be installed
                  by Lucent, the site-readiness specifications for such
                  Products; and

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                           (h) the standard order-to-delivery interval for the
                  Products.

         Each future Product Addendum must be signed by a Vice President or
         higher-level officer of Allegiance, and by a duly authorized Lucent
         official, in order to be effective. Neither party shall be entitled to
         rely upon or to enforce the terms of any Product Addendum that is not
         authorized as provided in the preceding sentence. The terms and
         conditions set forth in the applicable Product Addendum shall apply to
         Allegiance's acquisition of the applicable Products regardless of
         whether such terms and conditions are incorporated by reference in the
         applicable Allegiance purchase order.

                  2.1.6 ORDERING PRODUCTS PURSUANT TO PRODUCT ADDENDA. This
         Section sets forth the process for Allegiance or the applicable
         Allegiance Affiliate to order Products from Lucent that are covered
         under a Product Addendum.

                           2.1.6.1 REQUESTS FOR QUOTE. All requests to acquire
                  Products covered under a Product Addendum shall be made by
                  Allegiance by means of a "REQUEST FOR QUOTE" issued from
                  time-to-time by Allegiance to the applicable Lucent
                  representative. Each Request for Quote shall include, among
                  other things: (a) identification of the applicable Product
                  Addendum and a description of the Product(s) to be acquired
                  from Lucent by Allegiance; (b) if required, a description of
                  the functional capabilities and Performance Standards for the
                  Product(s); (c) a description of the site at which the
                  Product(s) will be installed; and (d) the start and completion
                  dates for implementation of the Product(s).

                           2.1.6.2 QUOTES. Except as provided in SECTION
                  2.1.6.3, Lucent shall respond to any Allegiance Request for
                  Quote in writing within ten (10) business days after its
                  receipt thereof, or within such other period of time as the
                  parties may mutually agree, by means of a "QUOTE" that shall
                  include the items set forth in SCHEDULE 2.1.6.2, as
                  applicable. Lucent shall be responsible for all costs and
                  expenses incurred in preparing a Quote. The Quote must be
                  signed by Lucent, and once signed shall constitute an offer to
                  sell the Product(s) or other items on the terms set forth
                  therein. Each Quote shall include and reference, among other
                  things and as applicable:

                                    (a) an  agreement to supply the Product(s)
                           and/or Services requested in the Request for Quote
                           and the proposed pricing for such Product(s) and/or
                           Services;

                                    (b) a  statement as  to whether the
                           Product(s) constitute initial Product(s) or growth
                           Product(s), and a list of any Third Party Products
                           that are to be provided as part of the Product;

                                    (c) a statement of compliance with the terms
                           of the applicable Product Addendum and the Request
                           for Quote and/or a list of exceptions, if any, to the
                           terms of the Product Addendum and/or Request for
                           Quote;

                                    (d) a Certification Test Plan and/or
                           Installation Test Plan prepared in accordance with
                           the terms of ARTICLE 7;

                                    (e) an Implementation Workplan prepared in
                           accordance with the terms of SECTION 6.1;

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                                    (F) a description of any Custom Programming
                           to be performed in connection with implementation of
                           the Product(s) and a pricing proposal for such Custom
                           Programming;

                                    (g) a detailed and complete description of
                           the assumptions underlying Lucent's recommended
                           Equipment configuration; and

                                    (h) a confirmation by Lucent that it has
                           complied with any and all homologation requirements
                           that are applicable to the Product and/or its use by
                           Allegiance.

                           2.1.6.3 SHORT-FORM QUOTE. If requested by Allegiance
                  in its Request for Quote, within three (3) business days after
                  its receipt of Allegiance's Request for Quote, Lucent shall
                  provide to Allegiance a "SHORT-FORM QUOTE" that includes the
                  items specified in this Section. Lucent shall be responsible
                  for all costs and expenses incurred in preparing a Short-Form
                  Quote. Each Short-Form Quote shall include: (a) a budgetary
                  price or model price for the applicable Product(s); and (b) a
                  statement as to the time frames required for Lucent to deliver
                  and/or install the applicable Product(s). Following its review
                  of the Short-Form Quote, Allegiance may request that Lucent
                  submit a full Quote in accordance with the terms set forth in
                  SECTION 2.1.6.2.

                           2.1.6.4 NEGOTIATION OF QUOTE. If Allegiance disagrees
                  with the terms of the Quote, the parties shall discuss those
                  items in the Quote about which the parties disagree, and
                  Lucent shall thereafter revise the Quote to reflect the
                  parties' agreed resolution of such items and resubmit the
                  Quote to Allegiance for its approval. The foregoing process
                  shall repeat as often as necessary until the parties have
                  reached agreement on the terms of the Quote. Any obligation to
                  acquire and/or license the Products and/or Services set forth
                  in a Quote shall arise only when Allegiance issues a formal
                  purchase order for the Products and/or Services as provided in
                  SECTION 2.3.

                           2.1.6.5 PURCHASE ORDERS FOR SWITCH PRODUCTS. The
                  parties acknowledge and agree that a formal manufacturing
                  reservation process is required for Switch Products and that
                  Lucent's obligation to meet the applicable delivery date shall
                  be contingent on Allegiance issuing a purchase order for the
                  applicable Switch Product on a mutually agreed date that takes
                  into consideration such manufacturing reservation process.

         2.2      STATEMENTS OF WORK. Except for Products purchased pursuant to
a Product Addendum, all other Products and Services will be acquired by
Allegiance in accordance with a Statement of Work. All Statements of Work shall
include the items referenced in SCHEDULE 2.2 that are appropriate to the
Product(s) and/or Services being acquired thereunder.

         2.3      PURCHASE ORDERS. Subject to Allegiance's purchase commitment
set forth in SECTION 10.7, Allegiance shall have no obligation to purchase
Products and/or Services from Lucent, including pursuant to a signed Product
Addendum or Statement of Work, except pursuant to a purchase order that is: (a)
signed and issued by an authorized representative of Allegiance; (b) references
this Agreement and the applicable Product Addendum or Statement of Work; and (c)
is accepted by Lucent. Within twenty-four (24) hours (excluding Saturdays,
Sundays and Lucent Holidays) of Lucent's receipt of a purchase order, Lucent
shall confirm such receipt to Allegiance in writing. Lucent shall accept or
reject such purchase order within five (5) business days following Lucent's
receipt of the purchase order. If Lucent fails

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* NOTE: CERTAIN MATERIAL HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL
TREATMENT AND SUCH MATERIAL HAS BEEN FILED SEPARATELY WITH THE SEC.

to accept or reject such purchase order within such five (5) business day
period, the applicable purchase order shall be deemed accepted by Lucent.
Receipt for purposes of this Section may be accomplished by e-mail transmission.
If Allegiance desires an expedited response to the applicable purchase order,
Allegiance shall contact the Lucent Account Executive who shall exercise best
efforts to provide Lucent's response within the requested time frame. All
Products shall be delivered to the site designated in the applicable purchase
order. Orders placed by Affiliates for delivery of Products and/or Services
performed outside of the United States and Canada will be made pursuant to an
international Product Addendum or Statement of Work, as applicable. With respect
to all Products, Lucent will ship the release/version level of such Product as
noted by Allegiance on its purchase order, and Lucent shall not substitute a
different release/version of such Products without Allegiance's prior consent.

         2.4      DELIVERY OF PRODUCTS.

                  2.4.1 GENERAL. Lucent shall cause the applicable Products to
         be delivered to the installation location on the date specified by
         Allegiance in the applicable Allegiance purchase order, provided such
         date is consistent with the order-to-delivery intervals set forth in
         the applicable Product Addendum or Statement of Work. Lucent shall pay
         all costs of warehousing (except as provided in SECTION 2.4.2),
         insurance and any reasonable additional costs associated with delivery
         of the Product(s). Allegiance shall pay the costs of freight.

                  2.4.2 BILL-AND-HOLD PRODUCTS. If an order is for Bill-and-Hold
         Products, the phrase "Bill-and-Hold" must clearly and conspicuously
         appear on the purchase order. If Allegiance orders Bill-and-Hold
         Products, Lucent will defer final shipment of such Product(s) until the
         final ship date indicated on the purchase order or such final ship date
         as is mutually agreed between the parties, provided that in no event
         shall Lucent be obligated to hold Bill-and-Hold Products longer than
         one (1) year from the date of the applicable purchase order. Allegiance
         agrees to pay to Lucent a mutually agreed monthly stocking fee for any
         Bill-and-Hold Products held beyond the final ship date indicated on the
         purchase order or another date mutually agreed upon by the parties.

                  2.4.3 PRODUCT DELIVERY DELAYS. Upon three (3) business days
         written notice to Lucent prior to the scheduled delivery date,
         Allegiance may suspend or reschedule delivery of Products not in excess
         of ninety (90) calendar days beyond the date originally scheduled for
         the delivery thereof *. If any Allegiance-requested delivery suspension
         continues for ninety (90) calendar days beyond the originally scheduled
         delivery date for a Product, Allegiance shall either: (a) cancel the
         order, in which case the terms of SECTION 2.5 shall apply; (b)
         authorize Lucent to deliver the applicable Products to Allegiance; or
         (c) agree with Lucent to extend such ninety (90) day period *.

         2.5      PRODUCT DELIVERY CANCELLATIONS. Each Product Addendum will
specify the terms that apply to delivery cancellations for the Products covered
by such Product Addendum.

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                       ARTICLE 3 -- SOFTWARE AND EQUIPMENT

* NOTE: CERTAIN MATERIAL HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL
TREATMENT AND SUCH MATERIAL HAS BEEN FILED SEPARATELY WITH THE SEC.

         3.1      SOFTWARE LICENSE.

                  3.1.1 GRANT OF LICENSE. Upon delivery of Software and
         Documentation pursuant to this Agreement, subject to Allegiance's
         payment of the applicable fees and compliance with the applicable terms
         and conditions hereunder, Lucent grants to Allegiance a perpetual,
         worldwide (subject to SECTION 15.14.1, and except as may otherwise be
         set forth in the applicable Product Addendum or Statement of Work),
         unlimited number of users (except as may otherwise be set forth in the
         applicable Product Addendum or Statement of Work), non-assessable,
         fully paid, site unrestricted (except as may otherwise be set forth in
         the applicable Product Addendum or Statement of Work), non-transferable
         (except as set forth in SECTIONS 3.1, 3.5, 15.5 or in the applicable
         Product Addendum or Statement of Work), non-exclusive license: (a) for
         Allegiance and its Authorized Users to use the Software and
         Documentation; and (b) for Allegiance to copy the Software and
         Documentation as required for archival, backup, testing *.
         Notwithstanding the foregoing restrictions on transferability of
         Software licenses, but subject to any additional terms that may be set
         forth in the applicable Product Addendum or Statement of Work, in
         connection with a sale or pledge as security of any Lucent Products to
         a Third Party, Allegiance shall have the right to assign its Software
         license rights for Software included in such Lucent Products to such
         Third Party. Allegiance will provide all assistance reasonably
         requested by Lucent to enforce the license terms against any Third
         Party Authorized User.

                  3.1.2 OPTIONAL SOFTWARE FEATURES. Software licensed by Lucent
         to Allegiance under this Agreement may contain optional features which
         are separately licensed and priced. Optional features will not be
         activated by Allegiance without authorization from Lucent and
         Allegiance's payment of the applicable license fees, if any. If, in
         spite of Allegiance's commercially reasonable efforts to comply with
         the foregoing restriction, such features are activated, Allegiance
         promptly shall notify Lucent that such features were activated. If
         Lucent identifies activation of any such features in connection with
         the annual Product Assessment Review described in SECTION 1.8.3 of
         SCHEDULE 8.1, Lucent promptly shall notify Allegiance of the activation
         of such features. Upon any such notice by one party to the other party,
         at its option, Allegiance shall either discontinue its use of such
         features or, if otherwise a chargeable item to Allegiance, pay to
         Lucent the current license fees charged by Lucent for the activated
         features (subject to any applicable discounts that may then be
         available to Allegiance under this Agreement). Notwithstanding the
         foregoing, Allegiance shall * activate the Feature Activation Counting
         and Reconciliation feature ("FACR") in all 5ESS Switch Product
         Software, and Lucent shall provide to Allegiance on a quarterly basis
         all information compiled by Lucent through its use of FACR tracking.
         Lucent agrees that records and information gathered from the quarterly
         audits will be used exclusively for the purpose of billing Allegiance
         for optional RTU features activated by Allegiance.

                  3.1.3 VIRTUAL COLLOCATION. If a regional telephone operating
         company with which Allegiance is doing a "virtual collocation" (meaning
         a Product will be integrated into the regional telephone operating
         company's network) demands access to Software in order to ensure the
         regional telephone operating company's ability to maintain its network,
         Allegiance will provide such company with a copy of the Virtual
         Collocation Software License Agreement attached hereto as EXHIBIT 3 and
         advise the regional telephone operating company that it must sign and
         return the Virtual Collocation Software License Agreement to Lucent
         prior to being allowed access to the Software. Upon return of a
         properly executed Virtual Collocation Software License

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* NOTE: CERTAIN MATERIAL HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL
TREATMENT AND SUCH MATERIAL HAS BEEN FILED SEPARATELY WITH THE SEC.

         Agreement, Lucent will provide Allegiance a copy of the Virtual
         Collocation Software License Agreement. Allegiance agrees not to
         provide access or disclose any part of the Software to the regional
         telephone operating company until Allegiance has received a copy of the
         applicable signed Virtual Collocation Software License Agreement.

                  3.1.4 OWNERSHIP RIGHTS RESERVED. No title or ownership of
         intellectual property rights to the Software and Documentation or any
         copy, translation, compilation or other derivative work are transferred
         to Allegiance hereunder, and title and ownership to such Software and
         Documentation shall remain with Lucent. Allegiance shall not
         disassemble, reverse compile, reverse engineer or otherwise translate
         the Software licensed hereunder; provided, however, that Allegiance may
         reverse engineer or decompile the Software for the purpose of creating
         an interoperable computer program. *

                  3.1.5 ADDITIONAL LICENSING TERMS. The parties may agree in a
         Product Addendum or Statement of Work to additional product-specific
         license terms.

         3.2      *

                  3.2.1    *

                  3.2.2 ACCESS TO SPECIFICATIONS FOR * DATA MODELS AND SIMILAR
         INFORMATION. Provided Allegiance has paid the applicable * license fee,
         if any, set forth in the applicable Product Addendum, Lucent shall
         provide to Allegiance for its use in written and, if available,
         electronic format, * Documentation and other similar information for
         each * (excluding * that are internal to Lucent's Products) or
         modification thereof provided to Allegiance. Lucent shall permit
         Allegiance and its Third Parties to access the data base structures,
         data models, data schema, table structures, object libraries and other
         data and software elements of the Products (excluding * that are
         internal to Lucent's Products) necessary to develop * as described in
         SECTION 3.2.1. Third Party access to * Documentation will be subject to
         written license agreements with Lucent on reasonable non-discriminatory
         terms, including a grant back of a nonexclusive license to use any and
         all improvements and modifications (and the intellectual property
         rights embodied therein) to Lucent's Products or the database
         structures or other data or software elements of the Products listed
         above. If Allegiance itself develops the * or modification thereof,
         Allegiance hereby grants Lucent a nonexclusive, worldwide, perpetual
         right to use, copy, distribute (by means of sublicenses), modify, make
         and have made such * or modification (and the intellectual property
         rights embodied therein).

         3.2.3 COOPERATION. Subject to the cost allocations set forth below in
         this SECTION 3.2.3, if a modification to an * is required due to a
         Regulatory Requirement or a change or problem in a Third Party system,
         Lucent shall cooperate with Allegiance to work with all applicable
         Third Parties to modify the * as necessary so that the * performs in
         accordance with the applicable Documentation, Specifications,
         Performance Standards and Regulatory Requirements. If an * modification
         is required because of a Third Party system change or problem, Lucent
         shall implement such modification pursuant to a Procurement Document
         or, if such modification relates to an existing Product Addendum or
         Statement of Work, such modification shall be implemented in accordance
         with the Change Order process described in SECTION 6.4. If such
         modification is required due to a failure of the Lucent

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* NOTE: CERTAIN MATERIAL HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL
TREATMENT AND SUCH MATERIAL HAS BEEN FILED SEPARATELY WITH THE SEC.

         portion of the * to operate in accordance with the applicable
         Documentation, Specifications or Performance Standards, Lucent shall
         implement such modification at no additional cost to Allegiance in
         accordance with Lucent's warranties and Support and Maintenance
         Services obligations under this Agreement. If an * modification is
         required due to a Regulatory Requirement, such modification shall be
         implemented in accordance with the terms set forth in SCHEDULE 8.1
         and/or the applicable Product Addendum or Statement of Work.

         3.3      CUSTOM PROGRAMMING. Allegiance shall have the right to request
that Lucent develop Custom Programming including, without limitation, additional
*. Within ten (10) business days following receipt of such request, Lucent shall
advise Allegiance whether it will undertake such Custom Programming and, if
Lucent agrees to undertake such Custom Programming, prepare and submit to
Allegiance within ten (10) business days a written response that includes: (a)
the items required to be included in a Change Response, as described in SECTION
6.4; and (b) a description of the functionality, interoperability and
performance characteristics of the requested Custom Programming. If Allegiance
issues a purchase order for the Custom Programming, Lucent shall provide to
Allegiance a Statement of Work in accordance with the requirements set forth in
SECTION 2.2. Upon Allegiance's approval of the Statement of Work, Lucent shall
perform the Custom Programming in accordance with the terms of such Statement of
Work and this Agreement, including, without limitation, SECTION 9.8. Allegiance
shall have the right to terminate any Custom Programming project upon five (5)
business days prior written notice to Lucent, provided that in such event: (a)
Lucent shall discontinue the terminated Custom Programming Services; (b)
Allegiance shall pay to Lucent the cost of any such Services provided,
pro-rated, as appropriate, for any fixed-fee Custom Programming project, and the
cost of the actual expenses incurred by Lucent as of the date of termination;
and (c) Lucent shall provide to Allegiance any intermediate and/or partial
versions of such Custom Programming and any related Documentation resulting from
such Custom Programming project; provided, however, that such Software shall be
provided to Allegiance without warranty.

         3.4      *

                  3.4.1    *

                  3.4.2    *

                  3.4.3    *

         3.5      TRANSFER RIGHTS . Subject to network usage or other
limitations that may be set forth in the applicable Product Addendum or
Statement of Work, Allegiance shall have the right to transfer the Software to a
different operating system and/or to substitute, switch, exchange or replatform
the Servers on which the Software operates at no additional Software license
fees or other additional costs to Allegiance, provided that, in any such case,
Lucent supports the operating system and/or Servers to which Allegiance proposes
to transfer the Software. Provided Allegiance follows Lucent's instructions
contained in the Documentation or otherwise provided through training or
Lucent's Support and Maintenance Services, Lucent shall provide assistance to
Allegiance, at no additional cost, to address and/or correct any Product
migration problems encountered in connection with such transfer; otherwise, such
assistance shall be provided at the Service Rates. If Allegiance engages Lucent
to perform Services in connection with any such transfer, substitution,
switching, exchanging or replatforming, such Services shall be provided at the
Service Rates.

                                -12-                                CONFIDENTIAL

<PAGE>   21

         3.6      EQUIPMENT.

                  3.6.1 EQUIPMENT AND EQUIPMENT CONFIGURATION. Each Procurement
         Document will include a list of the Equipment components recommended by
         Lucent to operate the Product that will be provided by Lucent to
         Allegiance under such Procurement Document and/or a list of Equipment
         components that will be provided by Lucent under such Procurement
         Document. Allegiance shall retain the right to purchase Equipment
         directly from Third Party vendors. All Equipment purchased under this
         Agreement that is manufactured and/or supplied by Third Parties shall
         include the original manufacturer's warranty.

                  3.6.2 CLEI CODES. All Equipment components purchased by
         Allegiance from Lucent shall be marked by Lucent with a CLEI code. With
         each Equipment invoice, Lucent shall provide to Allegiance an
         electronic list of the CLEI codes for each Equipment component
         purchased thereunder.

                  3.6.3 TITLE, RISK OF LOSS. Upon shipment of any Equipment sold
         by Lucent to Allegiance hereunder, Lucent shall provide to Allegiance a
         bill of sale transferring title to such Equipment to Allegiance free of
         any and all liens or encumbrances. Lucent shall represent and warrant
         in such bill of sale that the Equipment and any components thereof are
         entirely new. Risk of damage or loss to the Equipment shall pass to
         Allegiance upon delivery of the Equipment to the installation location
         specified in the applicable Allegiance purchase order; provided,
         however, that: (a) Lucent shall remain responsible for damage or loss
         to Equipment caused by its employees, agents and subcontractors; and
         (b) if Allegiance specifically requests delivery of Equipment to a
         Third Party value-added shipping agent (including, for example, Pegasus
         for IDLC Products), risk of loss or damage shall pass to Allegiance
         upon delivery to the Allegiance-designated Third Party value-added
         shipping agent.

                  3.6.4 SUBSTITUTIONS. Lucent shall not substitute any item of
         Equipment (excluding upgrades or updates to component parts that do not
         affect the form, fit, function or performance characteristics of the
         Equipment) for another item of Equipment without Allegiance's prior
         written consent. Lucent may be permitted to substitute temporarily an
         item of Equipment that does not meet the criteria set forth above if:
         (a) any ordered item of Equipment is unavailable to meet the delivery
         requirements of Allegiance as specified in the applicable Procurement
         Document; (b) Lucent provides prior written notice of the substitution
         to Allegiance; and (c) Allegiance consents in writing to the proposed
         substitution, which writing must be signed by the Allegiance Project
         Manager or higher-level signatory of Allegiance. If Lucent substitutes
         an item of Equipment as described herein, the cost of installation and
         removal of such substitute Equipment shall be at Lucent's sole cost and
         expense. Title to any temporarily substituted Equipment shall at all
         times remain with Lucent, provided that if Allegiance elects to accept
         such items, title shall pass to Allegiance upon Product Acceptance, and
         Lucent shall have the right to invoice Allegiance for such items.

                                -13-                                CONFIDENTIAL

<PAGE>   22

* NOTE: CERTAIN MATERIAL HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL
TREATMENT AND SUCH MATERIAL HAS BEEN FILED SEPARATELY WITH THE SEC.

                  3.6.5    REPLACEMENT PARTS FOR EQUIPMENT AND RELATED FIRMWARE.

                           3.6.5.1 AVAILABILITY. For a minimum period of *
                  following Allegiance's receipt from Lucent of any notice of
                  Product discontinuance for the applicable Product, which
                  notice of Product discontinuance shall be provided not less
                  than one (1) year prior to the date of Product discontinuance,
                  Lucent shall make available for purchase by Allegiance
                  functionally equivalent or better replacement parts for all
                  Equipment and related firmware (meaning that such replacement
                  parts shall be equivalent or better in form, fit, function,
                  capacity and performance) to maintain the Equipment and
                  related firmware in conformance at the time supplied with the
                  applicable Documentation, Specifications, Performance
                  Standards and Regulatory Requirements. On-site options for
                  spare and replacement parts, if any, shall be agreed to by the
                  parties pursuant to a Procurement Document. Allegiance shall
                  be treated as a priority customer of Lucent for purposes of
                  providing spare and replacement parts, within Lucent's top ten
                  percent (10%) of customers.

                           3.6.5.2 THIRD PARTY PARTS. Notwithstanding the terms
                  of SECTION 3.6.5.1, Allegiance shall not be obligated to
                  purchase replacement parts from Lucent, and Allegiance shall
                  have the right to procure replacement parts from any source.
                  If Allegiance procures replacement parts from sources other
                  than Lucent for reasons other than Lucent's failure to make
                  such replacement parts available, then at Allegiance's request
                  and expense, Lucent shall submit such replacement parts to the
                  testing and certification process described in SECTION 3.7. If
                  Allegiance is required to procure replacement parts from a
                  source other than Lucent due to Lucent's failure to make
                  replacement parts available as required by this Section, then
                  * Lucent shall submit such replacement parts to the testing
                  and certification process described in SECTION 3.7. If
                  Allegiance-supplied replacement parts become certified as
                  Compatible Products, Allegiance shall have the right to use
                  such replacement parts as part of any Products without
                  affecting the warranties set forth in ARTICLE 9 or the
                  applicable Procurement Document.

                           3.6.5.3 EQUIPMENT REPAIR AND/OR REPLACEMENT. All
                  Equipment and related firmware to be repaired or replaced
                  shall be shipped at Allegiance's expense and risk of loss to a
                  location designated by Lucent, and repaired or replaced
                  Equipment and related firmware shall be returned by Lucent to
                  Allegiance at Lucent's expense and risk of loss. If Lucent
                  provides to Allegiance advance replacement parts for any
                  Equipment and/or related firmware and Allegiance does not
                  return the corresponding defective item of Equipment and/or
                  related firmware to Lucent within thirty (30) calendar days
                  following Lucent's shipment of such replacement part to
                  Allegiance, Allegiance shall be responsible for the cost of
                  the replacement part; provided, however, that Lucent shall
                  have the right to bill such charges only to an open purchase
                  order designated by Allegiance for advance shipments of
                  replacement parts. With respect to Lucent Products that are
                  not readily returnable for repair, Lucent shall repair or
                  replace such Products at Allegiance's site, provided that
                  Allegiance shall make such Products accessible to Lucent
                  without charge. During the applicable Warranty Period, Lucent
                  shall be responsible for all costs related to such repair or
                  replacement, and following completion of such repair or
                  replacement, Lucent shall restore the site.

                                -14-                                CONFIDENTIAL

<PAGE>   23

                           3.6.5.4 REPORTING. Provided Allegiance elects to
                  obtain Lucent's NetCare(R) Services, Lucent shall provide to
                  Allegiance on a quarterly basis reports, at no additional
                  cost, specifying the types of Equipment and related firmware
                  replaced by Lucent during the preceding quarter along with the
                  nature of the Product Defects causing such replacement. If
                  Allegiance terminates NetCare(R) Services for the applicable
                  Product, Allegiance may obtain such reports on a
                  time-and-materials basis at the Service Rates.

                  3.6.6 DISCONTINUATION OF PRODUCTS. Lucent shall notify
         Allegiance of the discontinuation of any Products at least one (1) year
         prior to such discontinuation. If Lucent fails to provide Allegiance
         with such discontinuation notice, Lucent shall provide Allegiance with
         any replacement parts for such discontinued Products at the price of
         the part in effect prior to such discontinuation. Nothing contained
         herein shall be construed to diminish Lucent's Support and Maintenance
         Services obligations set forth in ARTICLE 8 nor Lucent's obligations
         under SECTION 3.6.5.

                  3.6.7 SITE PREPARATION. The terms of this Section shall apply
         only when Lucent will be performing installation Services requested by
         Allegiance. Each Product Addendum and Statement of Work may set forth
         the specifications and guidelines that the manufacturer of the Products
         prescribes for proper installation and operation of the Products. In
         consultation with Lucent, Allegiance shall prepare the installation
         location in accordance with such specifications and guidelines. Upon
         written notice from Allegiance that such requirements have been
         fulfilled, Lucent shall inspect the installation site and either
         acknowledge in writing that the installation site is suitable for
         effective installation and operation of the Products, or advise
         Allegiance in writing that the installation site does not materially
         comply with such requirements and the reasons for such material
         noncompliance. The suitability of Allegiance's site preparation shall
         be deemed properly prepared if Lucent has failed to submit a written
         statement of noncompliance to Allegiance before the earlier of: (a)
         five (5) calendar days following the date of Lucent's site inspection;
         and (b) five (5) calendar days following Allegiance's notice that the
         installation site requirements have been fulfilled, provided that
         Allegiance shall not give notice that the installation site
         requirements have been fulfilled more than five (5) calendar days prior
         to the commencement of installation activities with respect to the
         applicable Product, and Lucent shall not be excused for any delay in
         achieving any Critical Path Milestone if the cause of such delay is
         based upon Lucent's failure to notify Allegiance of any such
         noncompliance.

         3.7      COMPATIBLE PRODUCTS. To the extent available, Lucent shall
provide to Allegiance a listing of all Third Party hardware and software
components that may be used by Allegiance to operate with the Products acquired
under a Product Addendum or Statement of Work without adversely affecting the
representations, warranties and covenants contained in ARTICLE 9 ("COMPATIBLE
PRODUCTS"). Such Compatible Products shall include new Third Party hardware and
software components that Lucent may add or certify from time to time. If
Allegiance wants to certify any Allegiance-supplied product
("ALLEGIANCE-SUPPLIED PRODUCT") as a Compatible Product (including, without
limitation, Third Party replacement parts as described in SECTION 3.6.5),
Allegiance shall submit such Allegiance-Supplied Product to Lucent for testing
and certification and Lucent shall perform such testing and certification for a
mutually agreed upon fee or at the Service Rates set forth in SCHEDULE 10.
Lucent shall not unreasonably withhold its certification of any
Allegiance-Supplied Product as a Compatible Product.

         3.8      PURCHASE ORDERS AND SHIPMENT REPORTS. Upon Allegiance's
request, Lucent shall furnish to Allegiance, in a form agreeable to the parties,
monthly purchase order and shipment reports and/or quarterly invoice summary
reports.

                                -15-                                CONFIDENTIAL

<PAGE>   24

* NOTE: CERTAIN MATERIAL HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL
TREATMENT AND SUCH MATERIAL HAS BEEN FILED SEPARATELY WITH THE SEC.

                              ARTICLE 4 -- SERVICES

         4.1      GENERAL. Lucent shall perform Services in accordance with the
terms set forth in this Agreement and in the applicable Product Addendum or
Statement of Work.

         4.2      RIGHT TO ACCESS; IDENTIFICATION CREDENTIALS; FACILITY RULES.

                  4.2.1 RIGHT OF ACCESS. Upon reasonable prior notice, each
         party shall provide to the other party reasonable physical access to
         its facilities in connection with the performance of such party's
         obligations hereunder. Access to a party's facilities shall be subject
         to such party's security rules, policies and procedures. No charge
         shall be made for such access. If, in connection with providing
         Services hereunder, Lucent requires access to the facilities of a local
         exchange carrier's collocation environment, Lucent shall comply with
         any requirements such local exchange carrier imposes on its own
         employees with respect to facility security and drug screening tests.

                  4.2.2 IDENTIFICATION CREDENTIALS. Each party shall have the
         right to require the other party's employees, agents, representatives
         and subcontractors to exhibit identification credentials issued by such
         party in order to exercise any right of access under this Agreement.

                  4.2.3 FACILITY RULES. All employees, agents, representatives
         and subcontractors of a party shall, while on the other party's
         premises, comply with all rules and regulations that have been provided
         to such party. Lucent shall acquaint itself with the conditions
         governing the delivery, receipt and storage of Products at the
         installation site so that Lucent's installation activities will not
         unduly interfere with Allegiance's day-to-day operations at the
         installation site. Lucent shall not stop, delay or interfere with
         Allegiance's day-to-day operations without the prior written consent of
         an authorized Allegiance representative. Lucent shall provide and
         maintain sufficient covering to protect Allegiance's equipment,
         furniture and other items from Lucent's installation activities.

         4.3      COMPLIANCE WITH LOCAL EMPLOYMENT/LABOR LAWS. Lucent or its
Affiliates shall be responsible for compliance with all applicable laws, rules
and regulations with respect to all Lucent and/or its Affiliates, employees and
agents including, without limitation, employment of labor, hours of labor,
working conditions, payment of wages and payment of taxes, unemployment, social
security and other payroll taxes, including obtaining applicable contributions
from such personnel when so required by law.

         4.4      *

                      ARTICLE 5 -- ACCOUNT ADMINISTRATION,
                        PROJECT MANAGEMENT AND PERSONNEL

         5.1      GENERAL ACCOUNT ADMINISTRATION.

                  5.1.1 COVENANT OF COOPERATION. Lucent shall cooperate fully
         with Allegiance as necessary to install and implement each Product and
         to complete each project, and shall disclose such information to
         Allegiance relating to Lucent, the Products and Services as may be
         required or necessary to install and implement each Product and to
         complete each project. The parties agree

                                -16-                                CONFIDENTIAL

<PAGE>   25

         that joint planning and experienced personnel are critical factors for
         successful completion of each project and Product implementation.

                  5.1.2 EXECUTIVE BRIEFINGS. Lucent acknowledges that the
         Products are a significant investment involving a substantial
         commitment from Allegiance in the form of monies, resources, time and
         effort. Lucent further acknowledges that the Products are composed of
         dynamic and constantly changing and evolving technologies and that
         Allegiance will, therefore, require quarterly (or more frequent
         intervals at Allegiance's request) executive briefings from key Lucent
         executives (at a level mutually agreed upon by the parties) at
         locations specified by Allegiance regarding the status of, and
         developments affecting, Allegiance's investment including, without
         limitation a description of all features and functions that Lucent
         expects to include in future releases of the Products. As a dynamic
         telecommunications systems provider, Allegiance wants to incorporate
         new and valuable technologies into its telecommunications products,
         systems and services on an ongoing basis as it may deem appropriate.
         Accordingly, subject to any applicable Third Party non-disclosure
         obligations, Lucent agrees to advise Allegiance of all technological
         advances and breakthroughs of which it is aware that are relevant to
         the Products and that may enhance the functionality, reliability,
         performance and/or other qualities of the Products. Except as otherwise
         provided in this Agreement, equipment, software and services necessary
         to implement such new technologies are acknowledged to be outside the
         cost of the Products.

                  5.1.3 REVIEW OF CONTRACTUAL MATTERS. In addition to reviewing
         Lucent's technological developments as provided in SECTION 5.1.2, the
         parties agree to review in their periodic executive briefing sessions
         key matters relating to the parties' obligations under this Agreement
         including, without limitation:

                           (a) Lucent's ability to administer Allegiance's needs
                  on a global basis;

                           (b) performance of the Products;

                           (c) the financial arrangements set forth herein;

                           (d) Allegiance's satisfaction with the Allegiance
                  Account Team, including the Allegiance Account Teams' service
                  levels and responsiveness to Allegiance's needs;

                           (e) future Allegiance business and technical needs;
                  and

                           (f) such other matters as one party may bring to the
                  other.

         5.2      LUCENT COOPERATION WITH CONSULTANTS. Lucent acknowledges that
Allegiance is now and will be, during the course of this Agreement, working with
a number of Third Parties in developing, installing, maintaining and supporting
Allegiance's telecommunications products, systems and services, and Lucent shall
cooperate with Allegiance to work with all Third Parties as may be necessary to
accomplish such activities. Lucent shall disclose, or shall authorize Allegiance
to disclose, as applicable, Lucent Confidential Information as requested by
Allegiance to Third Parties who have a need to know such Confidential
Information in order to perform services for Allegiance, provided that such
Third Parties are subject to written agreements containing obligations to
maintain the confidentiality of Lucent's Confidential Information with
Allegiance and are not direct competitors of Lucent.

         5.3      LUCENT PERSONNEL. Lucent shall provide sufficient qualified
personnel with appropriate experience to perform Lucent's obligations hereunder
in accordance with the Services warranty set forth in SECTION 9.8.

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* NOTE: CERTAIN MATERIAL HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL
TREATMENT AND SUCH MATERIAL HAS BEEN FILED SEPARATELY WITH THE SEC.

         5.4      REMOVAL OF LUCENT PERSONNEL BY ALLEGIANCE. Allegiance shall
have the right to require Lucent to replace any Lucent personnel whom Allegiance
deems to be unfit or otherwise unsatisfactory to perform Lucent's duties
hereunder. During the ten (10) business day period following such request for
replacement, designated representatives from each party shall meet to discuss
the request and any alternative solutions; however, if a solution acceptable to
Allegiance has not been reached by the end of such ten (10) business day period,
Lucent shall remove such Lucent personnel and replace such personnel in
accordance with the terms of SECTION 5.5. Race, gender, age, religion, national
origin and other legally discriminatory characteristics shall not be valid
grounds for any such request by Allegiance.

         5.5      REMOVAL/REASSIGNMENT OF LUCENT PERSONNEL BY LUCENT. Lucent
shall exercise reasonable best efforts to not remove or temporarily reassign
from Allegiance's account and/or projects, as applicable: (a) the Lucent Account
Executive; (b) any Lucent Project Manager or other Key Personnel; and/or (c) any
installation team personnel, in each case prior to the date on which such
personnel have completed performance of the Lucent obligations that they have
been assigned to perform under this Agreement and/or the applicable Procurement
Document. If it becomes necessary to remove or temporarily reassign any such
personnel, Lucent shall ensure that: (d) Allegiance is given prompt notice of
the anticipated removal/reassignment; (e) prior to removal/reassignment of the
applicable personnel, Lucent has identified the replacement personnel, which
replacement personnel must possess comparable experience and training as the
individual whom Lucent intends to replace/reassign; and (f) at no additional
cost or expense to Allegiance, the personnel to be removed/reassigned must work
with the replacement personnel for a mutually agreed transition period, the
duration of which shall be jointly determined by the parties based on the duties
and responsibilities of the person being replaced/reassigned. At no time shall
there be a vacancy or gap in the position of Lucent Account Executive, Lucent
Project Manager or other Key Personnel unless otherwise agreed to by the parties
in writing. * Provided the replaced/reassigned personnel remains employed by
Lucent, such personnel shall continue to be available by telephone to answer any
questions relating to the duties and obligations formerly preformed by such
personnel. Either party's request for removal or reassignment of personnel shall
not excuse Lucent from meeting any Critical Path Milestones.

         5.6      ALLEGIANCE PERSONNEL. Allegiance shall provide personnel to
perform its obligations under this Agreement and any Procurement Document,
including a Product and/or Project Manager, as applicable, for each Product or
project (each an "ALLEGIANCE PROJECT MANAGER"), who may be identified in the
applicable Product Addendum or Statement of Work, act as a liaison between
Lucent and Allegiance, coordinate Allegiance resources, coordinate Allegiance
personnel, and have overall responsibility for meeting Allegiance's
responsibilities and obligations.

         5.7      STATUS MEETINGS AND REPORTS. On the dates and at the locations
specified in the applicable Implementation Workplan, and in any event no less
than monthly, the Lucent Project Manager and other Key Personnel, the Allegiance
Manager, other appropriate representatives of the parties and any necessary
Third Parties shall meet at an Allegiance-designated site or by telephone
conference, as determined by Allegiance, to discuss the status of Product
installations and, as applicable, each project, and any difficulties or issues
that may exist, including personnel issues and any proposed changes to any
Critical Path Milestones and/or changes to any date or other item set forth in
the applicable Implementation Workplan. The parties acknowledge that any change
of a Critical Path Milestone date shall require a mutually agreed Change Order.
The parties shall keep records of all status meetings and issue copies of the
records to all meeting attendees. At each status meeting, Lucent shall present
to Allegiance a written

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<PAGE>   27

* NOTE: CERTAIN MATERIAL HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL
TREATMENT AND SUCH MATERIAL HAS BEEN FILED SEPARATELY WITH THE SEC.

report of the status of each Product installation and/or project covering the
items identified in SCHEDULE 5.7. The report shall include a summary, in such
detail as Allegiance shall reasonably request, of: (a) the accomplishments and
difficulties encountered during the prior reporting period; (b) suggestions and
proposed actions for dealing with and resolving any identified difficulties and
the anticipated results during the next reporting period; (c) a comprehensive
and consolidated log of all outstanding Product or project-related problems
identified by Allegiance and Lucent that remain to be resolved; and (d) if
applicable, identification of any Allegiance or Third Party delays or other
circumstances known by Lucent that Lucent claims have impacted or will impact
its ability to meet any Critical Path Milestone. Allegiance shall have the right
to assume that Lucent does not know of any problems, difficulties or issues that
may have an adverse impact on the installation of Products or on a project
(whether from a timing, cost or performance standpoint) unless Lucent
specifically identifies such problems, difficulties or issues in its written
status reports.

         5.8      ADMINISTRATION OF PROJECTS. The Allegiance Project Manager and
the Lucent Project Manager and/or Lucent Account Executive, as applicable, for
the applicable Product Addendum or Statement of Work shall administer each
Procurement Document, the Change Order process set forth in SECTION 6.4 and all
decisions requiring the consent and/or approval of the other party, except for
those decisions requiring the consent and/or approval of Allegiance pursuant to
the terms set forth in SECTIONS 15.5, 15.6 and 15.15, which consent and/or
approval shall be effective only upon a written notice signed by a Vice
President or higher-level officer of Allegiance. All consents and/or approvals
made in contravention of the terms set forth in this Section shall be void and
of no force and effect. The Allegiance Project Manager, Lucent Project Manager
and/or Lucent Account Executive shall be responsible for identifying within
their respective organizations the individual(s) authorized to sign a Change
Order based on the dollar value of such Change Order.

                  ARTICLE 6 -- INSTALLATION AND IMPLEMENTATION

         6.1      IMPLEMENTATION WORKPLAN. When applicable for a particular
project or Product installation, a detailed implementation workplan
("IMPLEMENTATION WORKPLAN") shall be developed jointly by the parties and made a
part of the applicable Product Addendum or Statement of Work. The Implementation
Workplan shall include, as applicable: (a) identification of all milestone
events and interdependent milestone events; (b) identification of all critical
path milestones ("CRITICAL PATH MILESTONES") and the commencement and completion
dates for such Critical Path Milestones; (c) a detailed description of all
activities to be performed by Lucent and Allegiance, including task and sub-task
activities, the party responsible for, and the location of, on-site or off-site,
such activities; (d) for any Services rendered on a time-and-materials basis,
the number of hours required to perform each activity, task, sub-task and
Critical Path Milestone; (e) a detailed description of all activities to be
performed by Third Parties with whom Lucent is contracting including task and
sub-task activities; (f) identification of all interdependent activities; (g)
the dates and locations of scheduled status meetings, pursuant to SECTION 5.7;
(h) commencement and completion dates for the Product installation(s) or
project; and (i) commencement and projected end dates for Certification Testing
and Installation Testing, as applicable. The commencement and completion dates
for the Product installation(s) and/or project and related Critical Path
Milestones and any payment milestones shall not be changed without the prior
written consent of Allegiance.

         6.2      *

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         6.3      SPECIFICATIONS AND PERFORMANCE STANDARDS. Unless otherwise
stated in the applicable Product Addendum or Statement of Work, Lucent and
Allegiance shall develop for each Product, Services or project, as applicable,
technical specifications applicable to the Products and/or Services to be
delivered by Lucent ("SPECIFICATIONS") and Performance Standards that Lucent
must meet under the terms of this Agreement and applicable Procurement Document.

         6.4      CHANGE ORDER PROCEDURE. If either party believes that a change
in a Procurement Document, Implementation Workplan, project or other development
effort (whether in time frames, costs or deliverables) is necessary or
desirable, such party shall submit a written change request to the other (a
"CHANGE REQUEST"). Lucent shall not charge Allegiance a fee for de minimis
change orders that occur with respect to a particular Product installation,
project or other development effort; provided that the determination of whether
a change order is "de minimis" in nature shall be made with respect to the
entirety of such Product installation, project or other development effort.
Accordingly, if Change Requests are made, they will be presumed not to impact
the fees under this Agreement; provided, however, that if the Change Request
consists of other than a de minimis deviation from the scope of the Product
installation, project or other development effort, Lucent shall provide
Allegiance with written notification of such other deviation within five (5)
business days after receipt of the Change Request. If agreed to by Allegiance, a
change in the fee, if any, shall be made. If Allegiance initiated the Change
Request, within five (5) business days of Lucent's receipt of such Change
Request, Lucent shall provide to Allegiance a written statement describing in
detail: (a) the impact on the performance of the Product, project or other
development effort, if any, and the modifications to the Product, project or
other development effort that will be required as a result of the Change Request
including, without limitation, changes in the Products and Services; (b) the
effect of the Change Request on the applicable Implementation Workplan, project
or other development effort including any impact on any Critical Path Milestone
dates; and (c) an estimate of the cost to implement each Change Request
(collectively, the "CHANGE RESPONSE"). If Lucent submits a Change Request to
Allegiance, such Change Request shall include the information required for a
Change Response. Allegiance shall accept or reject any Change Response or
Lucent-initiated Change Request, as applicable, within ten (10) business days
after receipt of same from Lucent. If Allegiance accepts a Change Response or
Lucent-initiated Change Request in writing, such Change Response, together with
Allegiance's Change Request or such Lucent-initiated Change Request, shall be
deemed to be a "CHANGE ORDER" and shall become part of this Agreement and the
applicable Product Addendum or Statement of Work. If Allegiance rejects Lucent's
Change Response or Lucent-initiated Change Request or fails to respond to Lucent
in the time frame identified above, Lucent shall proceed to fulfill its
obligations under this Agreement and the applicable Procurement Document. The
parties may agree to different Change Order procedures pursuant to a Product
Addendum or Statement of Work.

         6.5      CONVERSIONS. If any conversions are required with respect to a
Product, Allegiance and Lucent will develop a conversion plan pursuant to the
applicable Product Addendum or Statement of Work that details the methods and
procedures Lucent plans to use to effectuate such conversion. When finalized,
such conversion plan shall be attached to the applicable Product Addendum or
Statement of Work.

         6.6      INSTRUCTION AND TRAINING.

                  6.6.1 GENERAL. Lucent shall provide to Allegiance the training
         Services described in the applicable Product Addendum or Statement of
         Work for the fees (if any) set forth therein.

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* NOTE: CERTAIN MATERIAL HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL
TREATMENT AND SUCH MATERIAL HAS BEEN FILED SEPARATELY WITH THE SEC.

                  6.6.2 * TRAINING *. **Training Services shall be made
         available to Allegiance on a timely basis given Allegiance's
         installation schedule. Within reason, class sizes at Allegiance's
         location shall not be limited in number. Allegiance shall reimburse
         Lucent for expenses incurred by on-site instructors in accordance with
         SECTION 10.3. Lucent shall provide to Allegiance a descriptive list of
         its current class offerings upon Allegiance's request. Lucent shall
         provide reports to Allegiance on a quarterly basis that specify the
         status of Allegiance's accumulation and use of training credits as
         provided herein.

         6.7      ACCESS TO FIRST OFFICE APPLICATION AND BROADCAST WARNING
MESSAGES. At any time upon Allegiance's request, and automatically in the case
of any known problems, Lucent shall provide to Allegiance all first office
application test results and BWMs relating to any of the Products acquired by
Allegiance hereunder. Allegiance acknowledges that: (a) Lucent shall in no event
be required to disclose the identity of any Lucent customer to which such items
may relate; and (b) all first office application test results provided by Lucent
to Allegiance are subject to the confidentiality restrictions set forth in
ARTICLE 12.

                      ARTICLE 7 -- TESTING AND ACCEPTANCE

         7.1      GENERAL. Switch Products shall be tested in accordance with
the testing procedures set forth in SECTION 2 of SCHEDULE 2.1.1. All other
Products shall be tested in accordance with a Certification Testing process or
Installation Testing process described below in this ARTICLE 7. With respect to
such other Products: (a) new Products and new releases and/or new versions of
Products shall be subject to the Certification Testing process, and once such
Product has been Certified as set forth in SECTION 7.3, additional units of such
Products shall then be subject to Installation Testing as set forth in SECTION
7.4; (b) existing, generally available Products (except for new releases and/or
new versions of Products that have not previously been subjected to
Certification Testing) shall be subject to Installation Testing only; and (c)
the parties agree that versions of the Products identified in SCHEDULE 7.1 shall
be subject to Installation Testing only.

         7.2      CERTIFICATION TESTING. Certification Testing for new Products
and new releases and/or new versions of Products shall involve testing within a
prescribed operating environment and will be conducted pursuant to a test plan
to be jointly developed by the parties ("CERTIFICATION TEST PLAN"), which will
incorporate testing methodologies to confirm that the Products operate in
accordance with the applicable Documentation, Specifications, Performance
Standards and Regulatory Requirements. A Certification Test Plan may be subject
to modification if a Product is recertified as provided below in this Section.
The time period for Certification Testing shall be set forth in the applicable
Product Addendum, Statement of Work or Certification Test Plan. Each
Certification Test Plan will describe the exact scope, methodologies and
procedures (including expected performance results) for testing the Product, and
may involve deployment of several Product units in different locations and
within different operating environments. Certification Testing shall include lab
testing and live, operational testing in Allegiance's network. Allegiance shall
have the right to modify or amend the scope, methodologies and procedures for
executing the testing process to include additional testing criteria as may be
reasonably necessary and agreed to by Lucent, and Lucent shall not unreasonably
withhold such agreement. If any Defects are discovered as a result of
Certification Testing, Lucent shall promptly correct such Defects.

                                -21-                                CONFIDENTIAL

<PAGE>   30

         7.3      PRODUCT ACCEPTANCE. The following conditions are necessary
for a Product to achieve "PRODUCT ACCEPTANCE": (a) all Material Defects
identified during Certification Testing have been corrected by Lucent; and (b)
Lucent has provided to Allegiance all Documentation and other deliverables
required to be provided to Allegiance pursuant to the applicable Product
Addendum or Statement of Work. Allegiance's use of the Product in a live,
production environment shall not by itself constitute Product Acceptance (under
contract law or the Uniform Commercial Code of Illinois). When Lucent believes
that all conditions necessary for a Product to achieve Product Acceptance have
been met, Lucent shall present to the applicable Allegiance Project Manager for
signature an "ACCEPTANCE CERTIFICATE", which Acceptance Certificate shall be in
the form attached hereto as SCHEDULE 7.3. If Allegiance disagrees that the
conditions required for Product Acceptance have been met, within ten (10)
business days following its receipt of the Acceptance Certificate from Lucent,
Allegiance shall detail its objections in writing. If Allegiance fails to object
to Lucent's Acceptance Certificate within the ten (10) business day period
described in the preceding sentence, Product Acceptance will be deemed to have
occurred with respect to the applicable Product. Lucent acknowledges that the
Acceptance Certificate must be signed by the applicable Allegiance Project
Manager or his or her designee, and Lucent shall not be entitled to rely on any
signature by any Allegiance employee, agent or representative other than such
Allegiance Project Manager or his or her designee. A Product will be "CERTIFIED"
when Allegiance determines the Product is stable within a prescribed operating
environment and can be migrated to an Installation Testing process. Changes to
an operating environment may require, at Allegiance's election, a
re-certification testing process for the Product for such changed operating
environment.

         7.4      INSTALLATION TESTING. For additional units of Products that
are Certified as provided in SECTION 7.3, and for existing, generally available
Products (except for new releases and/or new versions of Products that have not
previously been Certified), installation test plan(s) ("INSTALLATION TEST
PLAN(S)") shall be jointly developed by the parties and attached to the
applicable Product Addendum or Statement of Work, and such Products will be
subject to Installation Testing in accordance with the Installation Test Plan.
An Installation Test Plan may be subject to modification if a Product is
re-Certified under SECTION 7.3. The time period for Installation Testing shall
be set forth in the applicable Product Addendum, Statement of Work or
Installation Test Plan. If any Defects are discovered as a result of
Installation Testing, Lucent shall promptly correct such Defects.

         7.5      INSTALLATION ACCEPTANCE/PROJECT ACCEPTANCE. The following
conditions are necessary for "INSTALLATION ACCEPTANCE" or, with respect to
projects, "PROJECT ACCEPTANCE" to occur: (a) all Material Defects identified
during Installation Testing have been corrected by Lucent; and (b) Lucent has
provided to Allegiance all Documentation and other deliverables relating to that
Product or project in accordance with the terms of this Agreement and the
applicable Procurement Document(s). Nothing else, including Allegiance's use of
the Product or any portion thereof in a live, production environment, shall by
itself constitute Installation Acceptance or Project Acceptance (under contract
law or the Uniform Commercial Code of Illinois). When Lucent believes that all
conditions necessary to achieve Installation Acceptance or Project Acceptance,
as applicable, have been met, Lucent shall present to the applicable Allegiance
Project Manager for signature an Acceptance Certificate, which Acceptance
Certificate shall be in the form attached hereto as SCHEDULE 7.3. If Allegiance
disagrees that the conditions required for Installation Acceptance or Project
Acceptance, as applicable, have been met, within ten (10) business days
following its receipt of the Acceptance Certificate from Lucent, Allegiance
shall detail its objections in writing. If Allegiance fails to object to
Lucent's Acceptance Certificate within the ten (10) business day period
described in the preceding sentence, Installation Acceptance or Project
Acceptance, as applicable, will be deemed to have occurred with respect to the
applicable Product or project. Lucent acknowledges that the Acceptance
Certificate must be signed by the Allegiance Project Manager or his or her
designee, and Lucent shall not be entitled to rely on any signature by any
Allegiance employee, agent or representative other than such Allegiance Project
Manager or his or her designee.

                                -22-                                CONFIDENTIAL

<PAGE>   31

* NOTE: CERTAIN MATERIAL HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL
TREATMENT AND SUCH MATERIAL HAS BEEN FILED SEPARATELY WITH THE SEC.

         7.6      FAILURE TO ACHIEVE ACCEPTANCE. If Product Acceptance,
Installation Acceptance or Project Acceptance, as applicable, is not achieved
within thirty (30) calendar days after the scheduled date for Product
Acceptance, Installation Acceptance or Project Acceptance set forth in the
applicable Implementation Workplan or test plan, at is option in its sole
discretion, Allegiance shall either: (a) accept the Product or project, subject
to Lucent's obligation to correct any then-remaining Defects as part of its
Support and Maintenance Services obligations; or (b) declare an Event of Default
and, at its option, seek the rights and remedies available to it under ARTICLE
11.

         7.7      POST-ACCEPTANCE CORRECTION OF DEFECTS. Lucent shall correct
any Defects remaining to be corrected following Product Acceptance, Installation
Acceptance or Project Acceptance, as applicable, under the applicable Product
Addendum or Statement of Work in accordance with Lucent's warranty and/or
Support and Maintenance Services obligations under ARTICLE 8.

                  ARTICLE 8 -- SUPPORT AND MAINTENANCE SERVICES

         8.1      GENERAL. During the Warranty Period and thereafter for as long
as Allegiance elects to receive Support and Maintenance Services under the terms
of this Agreement and/or any applicable Product Addendum or Statement of Work
[whether on a time-and-materials basis (including, without limitation, pursuant
to Lucent's Time-and-Materials Support program for Switch Products as provided
in SCHEDULE 8.1) or pursuant to any of Lucent's standard post-Warranty Period
service plans as described in SCHEDULE 8.1], Lucent shall provide to Allegiance
the support and maintenance Services ("SUPPORT AND MAINTENANCE SERVICES")
described in this ARTICLE 8, in SCHEDULE 8.1 and in the applicable Product
Addendum or Statement of Work. Allegiance acknowledges that repair or
replacement of Equipment following expiration of the applicable Warranty Period
shall be at Allegiance's sole cost and expense.

         8.2      TERM AND TERMINATION. Support and Maintenance Services for a
Product acquired by Allegiance pursuant to a Product Addendum or Statement of
Work shall commence upon the beginning of the Warranty Period for the applicable
Product and shall extend for the duration of the applicable Warranty Period.
Thereafter, Lucent shall provide Support and Maintenance Services with respect
to a particular Product on a time-and-materials basis; provided, however, that
if Allegiance elects a Support and Maintenance Services plan as set forth in
SCHEDULE 8.1 upon written notice to Lucent, the term of such elective Support
and Maintenance Services plan shall be * and shall thereafter extend
automatically for * terms unless terminated: (a) by either party upon the
occurrence of an Event of Default by or with respect to the other party; (b) by
Allegiance upon ninety (90) calendar days' written notice to Lucent of its
election not to renew; or (c) by Lucent upon one (1) year's written notice to
Allegiance of its election not to renew. *

         8.3      THIRD PARTY PRODUCT SUPPORT AND MAINTENANCE SERVICES
GUARANTEES. If agreed upon by the parties in the applicable Product Addendum or
Statement of Work, Lucent shall provide to Allegiance Third Party Product
support and maintenance services guarantees, executed by the applicable Third
Party Product manufacturer or support and maintenance services provider, that
specify the term and support level to be provided by the manufacturer or
services provider, as applicable, and guarantee that such Third Party Products
or services, as applicable, will be available to Allegiance for the period of
time specified in the applicable Product Addendum or Statement of Work.
Allegiance shall either be a signatory or an expressly acknowledged third-party
beneficiary of all such guarantees. If requested by Allegiance, which request
shall serve as Allegiance's authorization, Lucent shall serve as a liaison
between Allegiance and

                                -23-                                CONFIDENTIAL

<PAGE>   32

* NOTE: CERTAIN MATERIAL HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL
TREATMENT AND SUCH MATERIAL HAS BEEN FILED SEPARATELY WITH THE SEC.

the applicable Third Party Product manufacturers for any Third Party
Product-related support requested by Allegiance, and such Services will be
provided at the Service Rates.

         8.4      SUPPORT AND MAINTENANCE SERVICES FEES. If Allegiance elects to
obtain Support and Maintenance Services from Lucent for a Product on other than
a time-and-materials basis, the fees for such Support and Maintenance Services
shall be set forth in the applicable Product Addendum or Statement of Work,
shall commence upon the date set forth in the applicable Product Addendum or
Statement of Work and shall be payable quarterly by Allegiance.
Time-and-materials Support and Maintenance Services shall be invoiced by Lucent
and payable by Allegiance on a monthly basis. Support and Maintenance Services
fees for a Product may be increased by Lucent once annually commencing one (1)
year following the date on which such fees began; provided, however, that Lucent
provides Allegiance written notice of such increases *.

         8.5      WARRANTY PERIODS. Unless a longer period is specified in any
Product Addendum or Statement of Work, the following warranty periods (each, a
"WARRANTY PERIOD") shall apply to Products procured by Allegiance under this
Agreement:

                  (a) LUCENT PRODUCTS. The Warranty Period for Lucent Products
         (except for Switch Products) shall commence upon the date specified in
         the applicable Product Addendum or Statement of Work and, unless
         lengthened upon agreement of the parties in such Product Addendum or
         Statement of Work, shall continue for the period of time set forth in
         SCHEDULE 8.5. Notwithstanding anything contained herein to the
         contrary, the Warranty Period for Products purchased as Bill-and-Hold
         Products as provided in SECTION 2.4.2 shall commence upon the earlier
         of: (a) delivery of such Product to Allegiance; or (b) ninety (90)
         calendar days from the date such Bill-and-Hold Products are stocked at
         Lucent's facility.

                  (b) SWITCH PRODUCTS. The Warranty Period for Switch Products
         purchased pursuant to this Agreement shall commence upon Turnover. The
         Warranty Period for Switch Products shall continue for the period of
         time set forth in SCHEDULE 8.5.

                  (c) THIRD PARTY PRODUCTS. The Warranty Period for any Third
         Party Products shall be the applicable manufacturer's warranty, unless
         such Third Party Products qualify as a Lucent Product, in which case
         the Warranty Period set forth in SUBSECTION (A) of this Section shall
         apply.

                  (d) REPAIRED EQUIPMENT; REPLACEMENT PARTS. The Warranty Period
         for Equipment repaired by Lucent at Allegiance's premises or
         replacement parts supplied by Lucent to Allegiance as provided in
         SECTION 3.6.5 shall be the longer of: (i) the time period specified in
         SCHEDULE 8.5; and (ii) the length of the unexpired Warranty Period for
         such repaired or replaced Equipment.

         8.6      SUPPORT AND MAINTENANCE SERVICES REPORT. Lucent shall furnish
on a periodic basis (but not less than each calendar quarter) a report
summarizing all invoices issued for Support and Maintenance Services, itemizing
the Products for which Lucent is providing Support and Maintenance Services, and
providing the cost basis for the Support and Maintenance Services provided for
each Product. The amount and type of detail disclosed, as well as the format of
the report shall be developed jointly by the parties and shall otherwise be
acceptable to Allegiance. The parties also shall meet on a periodic basis

                                -24-                                CONFIDENTIAL

<PAGE>   33

* NOTE: CERTAIN MATERIAL HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL
TREATMENT AND SUCH MATERIAL HAS BEEN FILED SEPARATELY WITH THE SEC.

(but not less than semi-annually) to discuss each quarterly report and Lucent's
performance of Support and Maintenance Services.

                   ARTICLE 9 -- REPRESENTATIONS AND WARRANTIES

         9.1      LUCENT PRODUCT FUNCTIONALITY WARRANTY. Lucent represents and
warrants to Allegiance that, during the applicable Warranty Period and
thereafter as long as Allegiance maintains Support and Maintenance Services for
the applicable Lucent Products, the Lucent Products provided under this
Agreement shall function in accordance with the applicable Specifications,
Documentation and Regulatory Requirements. If, under normal and proper use, a
Defect or other non-conformity appears in a Lucent Product and Allegiance
promptly notifies Lucent of such Defect or other non-conformity and follows
Lucent's instructions regarding the repair and/or return of such Lucent Product
to Lucent (in accordance with the terms of SECTION 3.6.5.3, to the extent the
Defect or other non-conformity relates to Equipment), Lucent will either repair,
replace or correct such Lucent Product *. If Lucent is unable to repair, replace
or correct the Defect or other non-conformity as provided herein, Lucent shall
provide a refund or credit to Allegiance of the original purchase price or
license fee paid by Allegiance for the defective or non-conforming Lucent
Product. Allegiance acknowledges that: (a) repair or replacement of Equipment
following expiration of the applicable Warranty Period shall be at Allegiance's
sole cost and expense; provided, however, that Allegiance further acknowledges
that certain items of Equipment may not be capable of repair following
expiration of the Warranty Period; and (b) repair or replacement of Software
following expiration of the applicable Warranty Period may, in accordance with
the terms set forth in SCHEDULE 8.1, involve an additional charge.

         9.2      *

         9.3      PERFORMANCE WARRANTIES.

                  9.3.1    *

                  9.3.2 COMPATIBILITY WARRANTY FOR PRODUCTS. Lucent represents
         and warrants that all Software supplied or recommended by Lucent
         pursuant to a Product Addendum or Statement of Work including, without
         limitation, any Custom Programming and all Enhancements to such
         Software, will operate compatibly on the Equipment supplied or
         recommended by Lucent pursuant to such Product Addendum or Statement of
         Work. The warranty and covenants contained in this Section shall remain
         in full force and effect for as long as Allegiance continues to receive
         Support and Maintenance Services from Lucent (including during the
         applicable Warranty Period).

                  9.3.3    *

         9.4      *

         9.5      EURO WARRANTY. Lucent represents and warrants to Allegiance
that each Product, all of its components, and all related products are able
accurately to process, exchange, accept, respond to, store and display any
currency values based on the Euro as of the date the Product is delivered in
accordance

                                -25-                                CONFIDENTIAL

<PAGE>   34

* NOTE: CERTAIN MATERIAL HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL
TREATMENT AND SUCH MATERIAL HAS BEEN FILED SEPARATELY WITH THE SEC.

with the Documentation, Specifications, Performance Standard and Regulatory
Requirements or as may otherwise be set forth in a Product Addendum or Statement
of Work.

         9.6      *

         9.7      THIRD PARTY WARRANTIES AND INDEMNITIES. Lucent hereby assigns
to Allegiance all end-user warranties and indemnities relating to Third Party
Products provided by Lucent to Allegiance. If Lucent is not permitted to assign
any of such end-user warranties and indemnities through to Allegiance, Lucent
shall enforce such warranties and indemnities on behalf of Allegiance to the
extent Lucent is permitted to do so under the terms of the applicable Third
Party agreements. In addition to the above, at Allegiance's request, Lucent
shall register Allegiance with any and all Third Party Product vendors who have
such registration programs such that Allegiance is acknowledged as a support
obligation and Allegiance can receive and obtain product notices directly from
the Third Party Product vendor. Lucent shall produce evidence of such
registration within thirty (30) calendar days from the date Allegiance requests
Lucent to obtain such registration.

         9.8      SERVICES WARRANTY. Lucent represents and warrants to
Allegiance that it shall perform such Services and provide the deliverables
required by this Agreement and any Product Addendum or Statement of Work in a
workman-like manner and in accordance with Lucent's standards for such Services
and industry practices and standards generally applicable to such Services in
the country in which such Services are provided; provided, however, that where
this Agreement or a Product Addendum or Statement of Work specifies a particular
standard or criteria for performance, this warranty is not intended to and does
not diminish that standard or criteria for performance.

         9.9      INTELLECTUAL PROPERTY WARRANTY. Lucent represents and warrants
to Allegiance that: (a) there are no lawsuits pending that allege that the
Products covered by the Product Addendum or Statement of Work infringe upon any
patent, trademark, copyright, trade secret or other intellectual property or
proprietary right of any Third Party; and (b) to the best of Lucent's knowledge,
there is no threatened suit or claim against Lucent, excluding threats made in
the course of patent licensing negotiations, by any Third Party based on an
alleged violation of such right. For purposes of this Section, the phrase "to
the best of Lucent's knowledge" means the knowledge of the appropriate counsel
within Lucent's legal department responsible for intellectual property claims
made against Lucent. This warranty shall survive the expiration or termination
of this Agreement.

         9.10     WARRANTY OF AUTHORITY. Each party represents and warrants to
the other that it has the right to enter into this Agreement. Lucent further
represents and warrants that there are no outstanding assignments, grants,
licenses, encumbrances, obligations or agreements (whether written, oral or
implied) that are inconsistent with this Agreement and the rights granted or
transferred herein. This warranty shall survive the expiration or termination of
this Agreement.

         9.11     WARRANTY OF TITLE. Lucent represents and warrants to
Allegiance that it has all sufficient rights to license the Software and/or sell
the Products and Equipment, as applicable, and, if necessary, to sublicense all
Embedded Third Party Software and other Lucent-provided Third Party Software
sublicensed to Allegiance, all for the perpetual term stated herein. Lucent
further represents and warrants that each Product shall be free and clear of all
liens, claims, encumbrances or demands of Third Parties. This warranty shall
survive the expiration or termination of this Agreement.

                                -26-                                CONFIDENTIAL

<PAGE>   35

         9.12     PENDING LITIGATION WARRANTY. Lucent represents and warrants to
Allegiance that, as of the Effective Date, there is no action, suit, claim,
investigation or proceeding pending, or to the best of Lucent's knowledge,
threatened against, by or affecting Lucent or the Products which, if adversely
decided, might adversely affect: (a) Lucent's ability to enter into this
Agreement; (b) Lucent's performance of its obligations herein; or (c)
Allegiance's use of the Products.

         9.13     ADDITIONAL WARRANTIES. Lucent's performance under this
Agreement shall include, in addition to the warranties set forth in this
Article, all representations and warranties set forth in any Product Addenda or
Statements of Work.

         9.14     CHANGE OF CONTROL WARRANTY. Lucent represents and warrants to
Allegiance that, as of the Effective Date, no Change of Control with respect to
Lucent is being considered, planned or pending by the Board of Directors,
shareholders or management of Lucent or by any Affiliate of Lucent.

         9.15     MATERIAL MISSTATEMENTS OR OMISSIONS. No representation or
warranty by Lucent that is contained in this Agreement or in any Schedule,
Exhibit or other Attachment hereto or in any Product Addendum or Statement of
Work contains any untrue statement of a material fact or omits to state a
material fact necessary to make the statements and facts contained herein or
therein not materially misleading.

         9.16     WARRANTY DISCLAIMER. THE WARRANTIES SET FORTH IN THIS
AGREEMENT AND IN ANY PRODUCT ADDENDA OR STATEMENTS OF WORK ARE THE ONLY
WARRANTIES OF EITHER PARTY AND NO OTHER WARRANTY, EXPRESS OR IMPLIED, WILL
APPLY, INCLUDING WITHOUT LIMITATION, IMPLIED WARRANTY OF MERCHANTABILITY AND
IMPLIED WARRANTY OF FITNESS FOR A PARTICULAR PURPOSE. LUCENT MAKES NO WARRANTY
WITH RESPECT TO DEFECTS RESULTING FROM ANY ACTS OF ALLEGIANCE, ITS AGENTS OR
THIRD PARTIES WITH RESPECT TO THE FOLLOWING: INCORRECT DATA PROVIDED BY
ALLEGIANCE, MODIFICATIONS (OTHER THAN AS SPECIFIED OR PERMITTED IN THE
DOCUMENTATION), MISUSE, NEGLECT, ACCIDENT OR ABUSE; IMPROPER WIRING, REPAIRING,
SPLICING, ALTERATION, INSTALLATION, STORAGE OR MAINTENANCE; USE IN A MANNER NOT
IN ACCORDANCE WITH LUCENT'S OR ITS VENDOR'S SPECIFICATIONS OR DOCUMENTATION, OR
FAILURE OF CUSTOMER TO APPLY PREVIOUSLY APPLICABLE, GENERALLY AVAILABLE AND
DEFECT FREE MODIFICATIONS OR CORRECTIONS. IN ADDITION, LUCENT MAKES NO WARRANTY
WITH RESPECT TO PRODUCTS WHICH HAVE HAD THEIR SERIAL NUMBERS OR MONTH AND YEAR
OF MANUFACTURE REMOVED, ALTERED AND, WITH RESPECT TO EXPENDABLE ITEMS, INCLUDING
(WITHOUT LIMITATION) FUSES, LIGHT BULBS, MOTOR BRUSHES, AND THE LIKE. NO
WARRANTY IS MADE THAT THE SOFTWARE WILL RUN UNINTERRUPTED OR ERROR FREE,
PROVIDED THAT THIS WARRANTY EXCLUSION DOES NOT DIMINISH LUCENT'S OTHER
WARRANTIES AND OBLIGATIONS CONTAINED IN THIS AGREEMENT.

                     ARTICLE 10 -- PRICING AND PAYMENT TERMS

         10.1     TIME AND METHOD OF PAYMENT.

                  10.1.1   INVOICING. All fees payable to Lucent under this
         Agreement shall be detailed, categorized and clearly stated on an
         invoice in accordance with the terms and conditions set forth in this
         Section. Unless otherwise agreed by the parties, all Lucent invoices
         shall be expressed in, and all amounts payable under this Agreement
         shall be payable in, U.S. Dollars. All related

                                -27-                                CONFIDENTIAL

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* NOTE: CERTAIN MATERIAL HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL
TREATMENT AND SUCH MATERIAL HAS BEEN FILED SEPARATELY WITH THE SEC.

         banking documents and correspondences shall be in English. Lucent shall
         invoice Allegiance as set forth in this Section, and Allegiance shall
         pay all net undisputed amounts due to Lucent under this Agreement
         within thirty (30) calendar days of Allegiance's receipt of Lucent's
         invoice, provided that: (a) for payments made using EFT, *; and (b)
         undisputed overdue invoices shall bear interest at the rate of one and
         one half percent (1.5%) per month, or the maximum rate permitted by
         law, whichever is less. Lucent shall submit all invoices to the
         following address:

                  Allegiance Telecom, Inc.
                  1950 Stemmons Freeway
                  Box 391
                  Dallas, Texas  75207

         or to such other address as may be specified by Allegiance upon notice
         to Lucent. Each invoice must reference: (c) the above invoice address;
         (d) the applicable purchase order number; (e) if available, the project
         number identified in the applicable purchase order; and (f) with
         respect to Bill-and-Hold Products, the scheduled Product delivery date.

                  10.1.2 PAYMENTS. Allegiance shall submit all payments other
         than EFT payments to Lucent at the following address:

                  If by regular mail:                *

                  If by overnight courier:           *

                  10.1.3 ELECTRONIC FUNDS TRANSFER. Allegiance shall have the
         right, but not the obligation, to pay any amounts due Lucent hereunder
         using electronic funds transfer ("EFT"). EFT payments by Allegiance
         shall be made to the following account of Lucent or such other account
         as is subsequently designated by Lucent in writing:

                                    *

         *

                  10.1.4 INVOICING FOR PRODUCTS AND BILL-AND-HOLD PRODUCTS. All
         payment terms for Products furnished by Lucent to Allegiance under the
         terms of this Agreement shall be set forth in the applicable Product
         Addendum or Statement of Work, provided that, unless the parties
         mutually agree otherwise, Lucent shall have the right to invoice
         Allegiance for Bill-and-Hold Products upon the earlier of: (a)
         completion of assembly at Lucent's facility; or (b) stocking at
         Allegiance's designated location, and such invoice will serve as
         Lucent's notification that the Bill-and-Hold Products are complete and
         ready to be released by Allegiance for final shipment. All pricing for
         such Products shall be set forth in a price list attached to the
         applicable Product Addendum or Statement of Work, and, with respect to
         countries that conform to the North American numbering plan, Lucent
         shall have the right to increase the pricing set forth in such price
         list *.

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<PAGE>   37

* NOTE: CERTAIN MATERIAL HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL
TREATMENT AND SUCH MATERIAL HAS BEEN FILED SEPARATELY WITH THE SEC.

                  10.1.5 INVOICING FOR SOFTWARE. All license fees for Software
         furnished by Lucent to Allegiance under the terms of this Agreement and
         related payment terms shall be set forth in the applicable Product
         Addendum or Statement of Work.

                  10.1.6 INVOICING FOR SERVICES. All Services rendered by Lucent
         to Allegiance shall be set forth in a particular Product Addendum or
         Statement of Work, and except for Support and Maintenance Services,
         payable at the service rates ("SERVICE RATES") set forth in the
         applicable Product Addendum or Statement of Work, which rates shall
         include any applicable discounts and not exceed the Service Rates set
         forth in SCHEDULE 10. If Service Rates are not specified in the
         applicable Product Addendum or Statement of Work, then, unless the
         parties agree otherwise, the Service Rates set forth in SCHEDULE 10
         shall apply. *.

                          10.1.6.1          *

                         10.1.6.2           *

         10.2     *

         10.3     TRAVEL POLICY, OUT-OF-POCKET EXPENSES AND OTHER CHARGES.
Allegiance shall reimburse Lucent for all reasonable travel and out-of-pocket
expenses incurred by Lucent, provided that such expenses conform to the travel
and out-of-pocket expenses policy attached hereto as SCHEDULE 10.3. Allegiance
shall have the right to modify such policy upon reasonable notice to Lucent.

         10.4     TAXES.

                  10.4.1 GENERAL. Lucent's prices are exclusive of any national,
         federal, state, provincial, local or other sales, use, excise,
         value-added, customs and other taxes or like charges arising hereunder
         and Allegiance shall reimburse Lucent, or pay all such taxes and
         charges directly, as appropriate. If Lucent has paid or will pay such
         taxes or charges on Allegiance's behalf, Lucent shall separately list
         on its invoices any such taxes or charges, except where Allegiance
         furnishes evidence of a lawful exemption. If value-added tax on the
         supplies of Lucent is payable by Allegiance under a reverse charge
         procedure (i.e., shifting of liability, accounting or payment
         requirement to recipient of supplies), Allegiance shall ensure that
         Lucent will not effectively be held liable for this value-added tax by
         the relevant taxing authorities or other parties. Where applicable,
         Lucent shall ensure that its invoices to Allegiance are issued in such
         a way that these invoices meet the requirements for deduction of input
         value-added tax by Allegiance. Allegiance shall in no event be liable
         for the payment of any taxes or like charges based upon the net income
         of Lucent.

                  10.4.2 SPECIAL PROVISION RELATING TO STATE SALES AND USE
         TAXES. If Allegiance takes possession of Products in the United States
         from Lucent and such transfer is subject to sales or use tax of a
         particular state in the United States, Allegiance will reimburse Lucent
         for any such taxes paid by Lucent over and above the purchase price for
         such goods; provided, however that Allegiance shall not reimburse
         Lucent for any such taxes charged against Lucent or Allegiance on
         account of Lucent's misdelivery or other failure to comply with
         Allegiance's delivery instructions.

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<PAGE>   38

* NOTE: CERTAIN MATERIAL HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL
TREATMENT AND SUCH MATERIAL HAS BEEN FILED SEPARATELY WITH THE SEC.

                  10.4.3 SPECIAL PROVISION RELATING TO TAXES ON PRODUCTS SOLD
         OUTSIDE THE UNITED STATES. With respect to Products sold outside the
         United States, Allegiance shall bear all taxes, duties, levies and
         other similar charges, however designated, imposed as a result of the
         sale and/or license of Products and/or Services under this Agreement
         including, without limitation, any tax which Allegiance is required to
         withhold or deduct from payments to Lucent, but specifically excluding:
         (a) any tax imposed upon Lucent in a jurisdiction outside the United
         States if such tax is allowable as a credit against the United States
         income taxes of Lucent; and (b) any net income tax imposed upon Lucent
         by any governmental entity. In order for the exclusion contained in
         SUBSECTION (A) to apply, Allegiance shall furnish to Lucent such
         evidence as may be in Allegiance's possession and required by United
         States taxing authorities to establish that such tax has been paid so
         that Lucent may claim the credit.

                  10.4.4 SPECIAL PROVISION RELATING TO TAXES ON SERVICES
         PROVIDED OUTSIDE THE UNITED STATES. To the extent required under
         applicable laws of the country in which international Services are to
         be performed ("HOST COUNTRY"), Lucent shall obtain any necessary
         permission and/or written documentary approval from the Host Country
         prior to importing Services into the Host Country pursuant to this
         Agreement. If Allegiance receives delivery of goods or Services
         supplied under the Agreement in a country other than the United States,
         Allegiance will pay any import fees, customs charges, value added tax,
         broker fees, excise charges and any other such fees charged upon goods
         or Services imported into the Host Country. Any other taxes and/or
         assessments imposed upon Lucent as a result of Lucent's performance
         under this Agreement outside of the United States, including without
         limitation, income, profit or withholding taxes or assessments, shall
         be timely paid by Lucent. Allegiance shall not be liable or otherwise
         responsible for the payment of any such taxes or assessments incurred
         by Lucent as a result of its performance of international Services
         under this Agreement.

         10.5     CUSTOMS DUTIES DRAWBACKS. Lucent reserves the right to claim
United States or foreign customs duty on all sales pursuant to this Agreement.
Allegiance shall cooperate reasonably with Lucent in this regard, at Lucent's
expense, including providing proof of exportation, advance notice of
exportation, certificates, endorsements or any other documentation or proof as
may be necessary for Lucent or its Affiliates to receive payment of the drawback
claims and, if required by the United States Customs Service or similar entity,
to the extent in Allegiance's possession by making the Products available for
examination by such Customs Service or entity at the Allegiance location where
the Products are installed provided that the requested cooperation shall not
unreasonably interfere with Allegiance's operations.

         10.6     *

         10.7     ALLEGIANCE PURCHASE COMMITMENT. During the three (3)-year
period commencing on January 1, 2000, Allegiance and its Affiliates shall
purchase a minimum of Three Hundred Fifty Million Dollars ($350,000,000) of
Products and Services from Lucent under this Agreement ("REVENUE COMMITMENT"),
which Revenue Commitment shall be satisfied incrementally as follows:

                  (i) Allegiance shall satisfy a minimum of Eighty Million
         Dollars ($80,000,000) of the Revenue Commitment on or before December
         31, 2000;

                                -30-                                CONFIDENTIAL

<PAGE>   39

* NOTE: CERTAIN MATERIAL HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL
TREATMENT AND SUCH MATERIAL HAS BEEN FILED SEPARATELY WITH THE SEC.

                  (ii) Allegiance shall satisfy a minimum of One Hundred Eighty
         Million Dollars ($180,000,000) of the Revenue Commitment on or before
         December 31, 2001; and

                  (iii) Allegiance shall satisfy the entire Revenue Commitment
         on or before December 31, 2002.

In September of each of 2000, 2001 and 2002, Lucent will provide to Allegiance a
status report that identifies Allegiance's progress toward meeting the
applicable annual Revenue Commitment. If the annual Revenue Commitment for
either 2000 or 2001 is not achieved by November 15 of the applicable year, or if
the annual Revenue Commitment for 2002 is not achieved by December 31, 2002,
then Allegiance will be invoiced for the shortfall. Such shortfall, if any, for
2000 and 2001, shall be treated as credits toward Allegiance's and its
Affiliates' purchases of Products and Services in the next succeeding year. Such
shortfall, if any, for 2002, shall constitute a cash payment for which credits
will not apply.

         10.8     *

                  10.8.1   *

                  10.8.2   *

                       ARTICLE 11 -- TERM AND TERMINATION

         11.1     TERM OF AGREEMENT. This Agreement shall remain in effect until
the parties no longer have any unfulfilled obligations under the Agreement or
upon mutual written agreement of the parties. Each Product Addendum and
Statement of Work shall remain in effect until the earlier to occur of: (a)
termination of such Product Addendum or Statement of Work by either party upon
the occurrence of an Event of Default with respect to the other party; (b)
completion of all Services and the acceptance by Allegiance of all deliverables
required thereunder; provided that, for any Product Addendum or Statement of
Work that involves the continued provision of Support and Maintenance Services,
the Product Addendum or Statement of Work, as applicable, shall continue until
the expiration or termination of such Support and Maintenance Services; (c)
termination of such Product Addendum or Statement of Work in accordance with
SECTION 11.7; or (d) expiration of the term of the Product Addendum or Statement
of Work, as applicable. Notwithstanding the foregoing, any terms of this
Agreement (including the terms of any Product Addenda or Statements of Work)
that would, by their nature, survive the expiration or termination of this
Agreement and/or the applicable Product Addendum or Statement of Work
(including, without limitation, any terms pertaining to Lucent's grant to
Allegiance of any perpetual licenses hereunder) shall so survive.

         11.2 EVENTS OF DEFAULT. The following shall constitute events of
default ("EVENTS OF DEFAULT") and that the occurrence of one (1) or more of such
Events of Default shall constitute a material breach of this Agreement which
shall allow a party, as applicable, to seek the rights and remedies set forth in
this Article:

                  (a) Lucent's failure to achieve a Critical Path Milestone or
         deliver a key deliverable to Allegiance within the time frame specified
         in the Implementation Workplan, provided such failure was not caused by
         the material action or inaction of Allegiance or a Third Party
         contractor or consultant of Allegiance, and in no event shall such
         failure be subject to a cure period;

                                -31-                                CONFIDENTIAL

<PAGE>   40

* NOTE: CERTAIN MATERIAL HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL
TREATMENT AND SUCH MATERIAL HAS BEEN FILED SEPARATELY WITH THE SEC.

                  (b) Failure of Lucent to complete successfully any
         Certification Testing or Installation Testing of a Product, provided
         such failure was not caused by the material action or inaction of
         Allegiance or a Third Party contractor or consultant of Allegiance, or
         failure of a Product to achieve Product Acceptance or failure of a
         project to achieve Project Acceptance, and in no event shall such
         failure be subject to a cure period;

                  (c) Lucent's failure to meet the Service Restoration response
         time for an SL1 Incident for a period exceeding three (3) consecutive
         calendar days;

                  (d) Lucent's material breach of any Support and Maintenance
         Services obligation as provided in ARTICLE 8 or any Product Addendum or
         Statement of Work, provided that such breach is not cured within
         fourteen (14) calendar days following receipt of written notice of such
         breach;

                  (e) Lucent's material breach of any representation or warranty
         set forth in this Agreement or in any Product Addendum or Statement of
         Work, provided that such breach, if curable, is not cured within the
         time frames specified in ARTICLE 9, if applicable, or if the breach
         does not arise out of ARTICLE 9, then within thirty (30) calendar days
         following receipt of written notice of such breach;

                  (f) Lucent's failure to maintain insurance coverage as
         specified in SECTION 13.5, provided that such failure is not cured
         within thirty (30) calendar days following receipt of written notice of
         such failure;

                  (g) Allegiance's failure to timely pay any undisputed amount
         owed to Lucent, provided that such failure is not cured within thirty
         (30) calendar days following receipt of written notice of such failure;

                  (h) Failure of a party to perform any other material
         obligation under this Agreement and/or a Product Addendum or Statement
         of Work, provided that such failure is not cured within thirty (30)
         calendar days following receipt of written notice of such failure;

                  (i) Lucent's failure to make any Deposit(s) required under *
         as provided in SECTION 3.4, and/or the applicable Product Addendum or
         Statement of Work, provided that such breach, if curable, is not cured
         within thirty (30) calendar days following receipt of written notice of
         such breach;

                  (j) The institution of bankruptcy, receivership, insolvency,
         reorganization or other similar proceedings by or against Lucent under
         any section or chapter of the United States Bankruptcy Code, as
         amended, or under any similar laws or statutes of the United States or
         any state thereof, if such proceedings have not been dismissed or
         discharged within sixty (60) calendar days after they are instituted;
         or the insolvency or making of an assignment for the benefit of
         creditors or the admittance by Lucent of any involuntary debts as they
         mature or the institution of any reorganization arrangement or other
         readjustment of debt plan of Lucent not involving the United States
         Bankruptcy Code; or any corporate action taken by the Board of
         Directors of Lucent in furtherance of any of the above actions; and

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<PAGE>   41

                  (k) Appointment of a receiver for all or substantially all of
         Lucent's assets or any corporate action taken by the Board of Directors
         of Lucent in furtherance of the above action.

         11.3     RIGHTS AND REMEDIES OF LUCENT UPON DEFAULT OF ALLEGIANCE. Upon
the occurrence of an Event of Default by or with respect to Allegiance, subject
to Allegiance's rights set forth in SECTION 11.4.3, Lucent shall be entitled to:

                  (a) discontinue performance of its obligations under the
         affected Procurement Document; and/or

                  (b) subject to the terms of SECTION 11.6, seek to recover
         damages from Allegiance; and/or

                  (c) if applicable, seek to obtain the additional rights and
         remedies set forth in SECTION 14.5; and/or

                  (d) terminate the affected Software license and affected
         Product Addendum(s) or Statement(s) of Work if the Event of Default
         relates to Allegiance's uncured material breach of: (i) any of the
         provisions of SECTION 3.1; (ii) any Software license terms set forth in
         a Product Addendum or Statement of Work; (iii) any Software license fee
         payment obligations; or (iv) any of the provisions of SECTION 12.2 as
         it relates to the Software.

Notwithstanding anything contained herein to the contrary, Lucent expressly
waives and disclaims any right or remedy it may have to de-install, disable or
repossess any Product or any portion thereof without due process of law.

         11.4     RIGHTS AND REMEDIES OF ALLEGIANCE UPON DEFAULT OF LUCENT.

                  11.4.1 GENERAL. Upon the occurrence of an Event of Default by
         or with respect to Lucent, Allegiance shall be entitled to any of the
         following remedies:

                           (a) terminate, in whole or in part, any affected
                  Procurement Document(s) and/or this Agreement; and/or

                           (b) subject to the terms of SECTION 11.6, seek to
                  recover damages from Lucent; and/or

                           (c) discontinue Support and Maintenance Services
                  under the affected Product Addendum(s) or Statement(s) of Work
                  and receive a refund of any pre-paid but unearned Support and
                  Maintenance Services fees, which refund shall be paid by
                  Lucent to Allegiance within fourteen (14) calendar days
                  following Lucent's receipt of Allegiance's notice of such
                  discontinuation; and/or

                           (d) if applicable, obtain the additional remedies
                  described in SECTION 11.4.3; and/or

                           (e) if applicable, seek to obtain the additional
                  rights and remedies set forth in SECTION 14.5.

                                -33-                                CONFIDENTIAL

<PAGE>   42

* NOTE: CERTAIN MATERIAL HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL
TREATMENT AND SUCH MATERIAL HAS BEEN FILED SEPARATELY WITH THE SEC.

                  11.4.2 RIGHT TO SET OFF. Allegiance shall have the right to
         set off any undisputed amounts owed to Lucent against any damages as
         determined by senior executives of the parties or charges assessed by
         Allegiance against Lucent in accordance with SECTION 6.2 of this
         Agreement or as permitted by any Product Addendum or Statement of Work.

                  11.4.3 TRANSITION RIGHTS. Upon a complete or partial
         termination of this Agreement and/or a Procurement Document for any
         reason, provided such termination results in the termination of
         Allegiance's right to use Products acquired thereunder, Allegiance
         shall have the option, for up to twelve (12) months (the "TRANSITION
         PERIOD"), to continue to use the applicable Product, or any portion
         thereof, for the purposes set forth herein. During such Transition
         Period, Lucent shall make available to Allegiance all Support and
         Maintenance Services and all other Services necessary for an orderly
         transition of the Product. If this Agreement and/or a Procurement
         Document is completely or partially terminated due to the occurrence of
         a Lucent Event of Default, the Services provided by Lucent during the
         Transition Period shall be provided at no cost. If this Agreement
         and/or a Procurement Document is completely or partially terminated due
         to the occurrence of an Allegiance Event of Default, the Services
         provided by Lucent during the Transition Period shall be provided at
         the Service Rates.

         11.5     ATTORNEYS' FEES. The prevailing party in any dispute, claim or
litigation relating to an alleged breach of this Agreement shall be entitled to
reimbursement of all of its costs and expenses, including reasonable attorneys'
fees, incurred in connection with such dispute, claim or litigation, including
any appeal therefrom. For purposes of this Section, the determination of which
party is to be considered the prevailing party shall be decided by the court of
competent jurisdiction or independent party (i.e., mediator or arbitrator) that
resolves such dispute, claim or litigation.

         11.6     LIMITATION OF LIABILITY.

                  11.6.1 LIMITATION UPON TYPES OF RECOVERABLE DAMAGES. EXCEPT AS
         OTHERWISE PROVIDED IN SECTION 11.6.3, NEITHER PARTY SHALL BE LIABLE FOR
         ANY CONSEQUENTIAL, INCIDENTAL, INDIRECT, EXEMPLARY, SPECIAL OR PUNITIVE
         DAMAGES, REGARDLESS OF WHETHER THE CLAIM GIVING RISE TO SUCH DAMAGES IS
         BASED UPON BREACH OF WARRANTY, BREACH OF CONTRACT OR NEGLIGENCE, EVEN
         IF A PARTY HAS BEEN ADVISED OF THE POSSIBILITY THEREOF.

                  11.6.2 CAP ON DAMAGES. EXCEPT AS OTHERWISE PROVIDED IN SECTION
         11.6.3, EACH PARTY'S CUMULATIVE LIABILITY FOR ANY AND ALL CLAIMS,
         CAUSES OF ACTION, DAMAGES AND LOSSES ARISING OUT OF OR RELATING TO THIS
         AGREEMENT *.

                  11.6.3 EXCLUSIONS FROM LIMITATIONS OF LIABILITY.
         Notwithstanding anything contained herein to the contrary, the
         limitations of liability contained in this Section shall not apply to:
         (a) either party's indemnification obligations under SECTION 13.1 and
         SECTION 13.2; (b) personal injury, including death, and damage to
         tangible property caused by the negligent or intentional acts of a
         party or its employees, agents or subcontractors; (c) damages arising
         out of any loss of data or other damage to data caused by a Disabling
         Code which was programmed by Lucent's employees or agents

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<PAGE>   43

         with an intent to cause a Product to become inoperable or compromised
         in functionality or performance; and (d) either party's obligation to
         pay litigation costs and attorneys' fees incurred by the other party in
         enforcing the terms of this Agreement as set forth in SECTION 3.4.2 and
         SECTION 11.5.

         11.7     TERMINATION WITHOUT CAUSE. Upon written notice to Lucent,
Allegiance shall have the right to terminate without cause any Statement of
Work. In such event: (a) Lucent shall discontinue its Services with respect to
such Statement of Work; (b) Allegiance shall be obligated to pay to Lucent: (i)
with respect to Statements of Work involving Services only, the cost of any
Services provided by Lucent, calculated at the Service Rates and pro-rated as
appropriate for any fixed-fee project, and the cost of the actual expenses
incurred by Lucent, in each case as of the date of Lucent's receipt of
Allegiance's written notice of termination; and (ii) with respect to Statements
of Work involving Software and Services: (A) if applicable, the items described
in SUBSECTION (b)(i) above; (B) any accrued but unpaid Software license fees;
and (C) the balance remaining due on any Lucent-provided Third Party Products.
Allegiance shall return to Lucent any Software covered under a Statement of Work
that is terminated without cause as provided in this Section.

         ARTICLE 12 -- PROPRIETARY RIGHTS, CONFIDENTIALITY AND SECURITY

         12.1     OWNERSHIP OF INTELLECTUAL PROPERTY. Any pre-existing
intellectual property and all improvements thereto owned by either party shall
remain the sole and exclusive property of such party. Except as otherwise set
forth in a Product Addendum or Statement of Work, all Custom Programming, and
all intermediate and partial versions thereof, as well as all Documentation,
program materials, flowcharts, notes, outlines and the like created in
connection therewith, and any formulas, processes, algorithms, ideas,
inventions, know-how or techniques and any other information generated by Lucent
during the course of performing such Custom Programming, and the copyright,
patent, trademark, trade secret and all other proprietary rights therein, and
derivative works created therefrom (collectively, the "WORK PRODUCT"), shall be
the sole and exclusive property of Lucent to the extent such Work Product does
not contain Allegiance's Confidential Information and intellectual property.
Allegiance shall have the right to use the features and functionality
represented by any such Custom Programming on an exclusive basis for a period of
time following Project Acceptance of such Custom Programming (the "EXCLUSIVITY
PERIOD"), such Exclusivity Period to be mutually agreed upon by the parties in
the applicable Product Addendum or Statement of Work for such Custom
Programming. If the parties cannot agree to an Exclusivity Period, such
Exclusivity Period shall be twelve (12) months. During the Exclusivity Period,
Lucent shall not provide the features and functionality represented by such
Custom Programming to any Third Party without Allegiance's prior written
consent, which Allegiance may withhold in its sole discretion. If Lucent
markets, sells, licenses or otherwise transfers the features and functionality
represented by such Custom Programming to any Third Party during the Exclusivity
Period (with Allegiance's written consent), or following the Exclusivity Period,
Allegiance shall be entitled to receive from Lucent a rebate up to the amount of
the fees paid by Allegiance to Lucent for such Custom Programming, and such
rebate formula shall be mutually agreed upon by the parties in the applicable
Product Addendum or Statement of Work or other written response for Custom
Programming, as applicable.

         12.2     CONFIDENTIAL INFORMATION. "CONFIDENTIAL INFORMATION" means any
material, data or information in whatever form or media of a party to this
Agreement that is provided or disclosed to the other, except for any information
that is: (a) publicly available or later becomes available other than through a
breach of this Agreement; (b) known to the Receiving Party or its employees,
agents or representatives prior to such disclosure or is independently developed
by the Receiving Party or its employees, agents or representatives subsequent to
such disclosure; or (c) subsequently lawfully obtained by the Receiving Party or
its employees, agents or representatives from a Third Party without obligations
of confidentiality. Confidential Information shall include the following
categories of information whether

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<PAGE>   44

disclosed orally or not marked as confidential: written deliverables, network
configurations, network architecture, Services rendered by Lucent to Allegiance,
financial and operational information, and other matters relating to the
operation of the parties' business, including information relating to actual or
potential customers and customer lists, customer usage or requirements, business
and customer usage forecasts and projections, accounting, finance or tax
information, pricing information, and any information relating to the corporate
and/or operational structure of Allegiance and its Affiliates, Products or
Services and any amendments thereto, any information exchanged between the
parties pursuant to the Existing Contract, any minutes, notes or other
information disclosed in the dispute resolution process described in ARTICLE 14
except and to the extent such minutes, notes and other information disclosed in
such are disclosed in the resolution of disputes related to this Agreement, and
all information and materials relating to Third Party vendors, systems
integrators or consultants of Allegiance that have provided or that may provide
in the future any part of Allegiance's information or communications
infrastructure to Allegiance. The party that has received Confidential
Information (the "RECEIVING PARTY") shall exercise the same degree of care and
protection with respect to the Confidential Information of the party that has
disclosed Confidential Information to the Receiving Party (the "DISCLOSING
PARTY") that it exercises with respect to its own Confidential Information and
shall not directly or indirectly disclose, copy, distribute, republish or allow
any Third Party to have access to any Confidential Information of the Disclosing
Party. Notwithstanding the above: (d) Allegiance may disclose Lucent
Confidential Information to Authorized Users who have a need to know and who are
not direct competitors of Lucent; (e) Allegiance may disclose Lucent
Confidential Information to Third Party consultants, Allegiance's suppliers and
Allegiance's systems integrator who have a need to know, who are not direct
competitors and who are subject to written agreements containing obligations to
maintain the confidentiality of Lucent's Confidential Information; (f) Lucent
may disclose Allegiance's Confidential Information to its employees, consultants
and independent contractors who have a need to know and who are not a direct
competitor of Allegiance, provided that for Lucent's consultants and independent
contractors such individuals or entities have previously executed a
confidentiality and non-disclosure agreement in a manner no less protective than
with respect to Lucent's own Confidential Information; and (g) either party may
disclose Confidential Information if so required by law (including court order
or subpoena), provided that such disclosure is made in accordance with the terms
of SECTION 12.4. The parties may agree in a Product Addendum or Statement of
Work to terms more restrictive than those set forth in this Section.

         12.3     RETURN OF CONFIDENTIAL INFORMATION. Unless otherwise
authorized, upon the earlier of termination of this Agreement or request of the
Disclosing Party, with respect to the Disclosing Party's Confidential
Information (except for any Software licenses and related Documentation paid for
by Allegiance, which Allegiance shall have the right to retain and use subject
to applicable licensing restrictions) the Receiving Party shall promptly either:
(a) return such Confidential Information and provide certification to the
Disclosing Party that all such Confidential Information has been returned; or
(b) destroy such Confidential Information and provide certification to the
Disclosing Party that all such Confidential Information has been destroyed.

         12.4     NOTIFICATION OBLIGATION. If the Receiving Party becomes aware
of any unauthorized use or disclosure of the Confidential Information of the
Disclosing Party, the Receiving Party shall promptly and fully notify the
Disclosing Party of all facts known to it concerning such unauthorized use or
disclosure. In addition, if the Receiving Party or any of its employees or
agents are requested or required (by oral questions, interrogatories, requests
for information or documents in legal proceedings, subpoena, civil investigative
demand or other similar process) to disclose any of the Confidential Information
of the Disclosing Party, the Receiving Party shall not disclose the Confidential
Information without providing the Disclosing Party with reasonable prior written
notice of any such request or requirement so that the Disclosing Party may seek
a protective order or other appropriate remedy and/or waive compliance with the
provisions of this Agreement. Notwithstanding the foregoing, the Receiving Party
shall exercise its

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<PAGE>   45

best efforts to preserve the confidentiality of the Confidential Information
including, without limitation, by cooperating with the Disclosing Party to
obtain an appropriate protective order or other reliable assurance that
confidential treatment will be accorded the Confidential Information by such
tribunal.

         12.5     EMPLOYEE/AGENT ACKNOWLEDGMENT. Neither party shall disclose
Confidential Information to any employee, agent or representative of the
respective party unless and until such employee, agent or representative has
been made aware that his or her obligations under this Agreement are subject to
confidentiality restrictions.

         12.6     CHANGE OF EMPLOYMENT. To the extent such information is
available and upon Allegiance's written request, Lucent shall promptly inform
Allegiance in writing of any change in employment of any employee of Lucent with
access to the Confidential Information and provide Allegiance with a copy of
such individual's confidentiality and non-disclosure agreement, if any.

         12.7     ENFORCEMENT OF CONFIDENTIALITY OBLIGATIONS. If any agent,
employee or representative of the Receiving Party or any Third Party working
with the Receiving Party breaches any of the confidentiality obligations
contained herein, the Receiving Party shall use its reasonable efforts to
enforce all aspects of any applicable confidentiality and non-disclosure
agreement against such Receiving Party's agent, employee, representative or
other Third Party or, upon the request of the Disclosing Party, shall assign all
of its rights under any such confidentiality and non-disclosure agreement to the
Disclosing Party without further consideration or action. The Receiving Party
shall cooperate with the Disclosing Party in any proceeding brought against such
Receiving Party's agent, employee, representative or other Third Party.
Notwithstanding anything contained herein to the contrary, the Receiving Party
shall be responsible for ensuring that all persons and entities to whom or which
the Receiving Party has disclosed the Disclosing Party's Confidential
Information comply with the confidentiality obligations set forth in this
Agreement.

         12.8     SURVIVAL. The terms of this Article shall survive the
expiration or termination of this Agreement.

                   ARTICLE 13 -- INDEMNIFICATION AND INSURANCE

         13.1     GENERAL. Each party (the "INDEMNIFYING PARTY") shall
indemnify, defend and hold the other party and such party's Affiliates, members,
directors, officers, shareholders, employees, representatives, agents,
attorneys, successors and assigns (collectively, the "INDEMNIFIED PARTIES")
harmless from and against any and all claims, liabilities, obligations,
judgments, causes of action, costs and expenses (including reasonable attorneys'
fees) (collectively "ACTIONS") arising out of: (a) personal injury, including
death, and tangible property damage caused by the negligent or intentional acts
of a party or its employees, agents and/or subcontractors; or (b) any negligence
or willful or reckless actions or misconduct of a party or its employees, agents
and/or subcontractors.

         13.2     PROPRIETARY RIGHTS INFRINGEMENT INDEMNIFICATION. Lucent shall
indemnify, defend and hold the Allegiance Indemnified Parties harmless from and
against any Actions alleging that the Products or Allegiance's use of the
Products constitutes a misappropriation or infringement upon any patent,
trademark, copyright, trade secret or other intellectual property or proprietary
right of any Third Party. Lucent shall defend against, and hold the Allegiance
Indemnified Parties harmless from, any such Actions and pay all litigation costs
(including the costs of any appellate bonds), all reasonable attorneys' fees,
settlement payments and any and all damages awarded by final judgment resulting
from any such claim. If any Product or any part thereof is held to constitute a
misappropriation or infringement of any patent, trademark, copyright, trade
secret or other intellectual property or proprietary right of any Third Party,
and Allegiance's use of such

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<PAGE>   46

* NOTE: CERTAIN MATERIAL HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL
TREATMENT AND SUCH MATERIAL HAS BEEN FILED SEPARATELY WITH THE SEC.

Proucts or any part thereof is enjoined or interfered with in any manner, at its
sole expense, within thirty (30) calendar days of such injunction or
interference, Lucent shall either: (a) procure for Allegiance the right to
continue using such Products free of any liability for infringement or
violation; (b) replace or modify such Products with a non-infringing system or
product of equivalent or better functionality that is reasonably satisfactory to
Allegiance; or (c) in the event Lucent is unable, after exercising its best
efforts to implement one of the options set forth in SUBSECTION (a) or (b)
above, accept return of the Products at Lucent's sole cost and expense and
refund to Allegiance an amount equal to the amounts paid by Allegiance to Lucent
for the Products under the applicable Procurement Document depreciated over the
following term and in the following amounts (commencing upon Product Acceptance
or Project Acceptance, as applicable):

                                                         *

         13.3     PROCEDURES FOR INDEMNIFICATION.

                  13.3.1 GENERAL. Promptly after becoming aware of same, the
         Indemnified Party shall notify the Indemnifying Party of any Third
         Party Action covered under the terms of SECTIONS 13.1 or 13.2, as
         applicable, for which the Indemnified Party seeks indemnification. For
         a period that shall not exceed ten (10) business days following any
         such notification, as provided herein, the Indemnified Party and
         Indemnifying Party shall investigate and discuss in good faith whether
         such claim is subject to indemnification under SECTIONS 13.1 or 13.2,
         as applicable. During such discussions, the Indemnified Party shall
         give the Indemnifying Party full access to all records, data and
         personnel of the Indemnified Party as may be reasonably necessary to
         make such determination. If the parties are unable to agree on whether
         the Indemnifying Party is required to indemnify the Indemnified Party
         under the terms of SECTIONS 13.1 or 13.2, as applicable, the
         Indemnifying Party, at its option, shall either assume or decline
         defense of the Third Party Action, including negotiations for its
         settlement or compromise.

                  13.3.2 DEFENSE ASSUMED. If the Indemnifying Party assumes
         defense of a Third Party Action as described herein, the Indemnified
         Party shall reasonably cooperate with the Indemnifying Party in the
         defense of such Action and may be represented, at the Indemnified
         Party's expense, by counsel of its choice, provided that, where the
         Indemnifying Party has assumed defense of a Third Party Action, the
         Indemnifying Party shall have sole control over such defense. The
         Indemnifying Party shall not be responsible for defending any claims
         other than those described in SECTIONS 13.1 or 13.2, as applicable,
         even if brought in the same suit. In addition to the foregoing, if a
         court of competent jurisdiction later determines that an Action for
         which the Indemnifying Party assumed defense was not eligible for
         indemnification under SECTIONS 13.1 or 13.2, as applicable, within
         thirty (30) calendar days following such determination, the Indemnified
         Party shall reimburse the Indemnifying Party in full for all judgments,
         costs and expenses (including attorneys' fees) incurred in connection
         with such Action.

                  13.3.3 DEFENSE DECLINED. If the Indemnifying Party declines to
         assume defense of any Action, and it is later determined by a court of
         competent jurisdiction that such Action was eligible for
         indemnification under SECTIONS 13.1 or 13.2, as applicable, within
         thirty (30) calendar days following such determination, the
         Indemnifying Party shall reimburse the Indemnified Party in full for
         all judgments, costs and expenses (including attorneys' fees) incurred
         in connection with such Action.

                                -38-                                CONFIDENTIAL

<PAGE>   47

                  13.3.4 SETTLEMENT OF CLAIMS. The Indemnifying Party shall not
         settle any claim, suit or Action without the prior written consent of
         the Indemnified Parties if such settlement: (a) materially diminishes
         any of the Indemnified Party's rights under this Agreement or seeks to
         impose additional obligations on the Indemnified Party; or (b) arises
         out of or is a part of any criminal action, suit or proceeding or
         contains a stipulation or admission or acknowledgement of any liability
         or wrongdoing (whether in contract, tort or otherwise) on the part of
         the Indemnified Party.

                  13.3.5 CONTRIBUTORY NEGLIGENCE; RIGHT OF CONTRIBUTION. Nothing
         contained herein shall bar a claim for contributory negligence or a
         party's right of contribution.

         13.4     SURVIVAL; NO LIMITATION OF LIABILITY. The terms of SECTIONS
13.1, 13.2 and 13.3 shall survive the expiration or termination of this
Agreement. Notwithstanding anything contained herein to the contrary, the terms
of SECTION 11.6.1 and SECTION 11.6.2 shall not apply to the parties'
indemnification obligations under this Article.

         13.5     INSURANCE. Lucent shall maintain in effect at all times during
the term of this Agreement insurance with a carrier with an A.M. Best rating of
A-XII or better and shall otherwise be acceptable to Allegiance. Such insurance
shall include, without limitation, the requirements set forth herein and in
SCHEDULE 13.5 against all losses, claims, demands, proceedings, damages, costs,
charges and expenses for injuries or damage to any person or property arising
out of or in connection with Lucent's performance or non-performance under this
Agreement and Lucent shall designate Allegiance and its Affiliates as
"additional insureds" on such insurance policies as specified in SCHEDULE 13.5.
Lucent shall, on or before the Effective Date and thereafter upon Allegiance's
reasonable request, provide Allegiance with validated copies of all applicable
endorsements naming Allegiance and its Affiliates as "additional insureds", as
required, and evidencing such coverage, which shall also state that Allegiance
shall be provided a minimum of thirty (30) calendar days prior written notice of
any proposed cancellation, or expiration without renewal, and five (5) business
days prior written notice of any proposed change in carriers or material terms
of coverage. Lucent shall obtain or otherwise arrange for levels of insurance
coverage for all subcontractors in appropriate amounts. Lucent shall maintain,
in its files, evidence of all subcontractors' insurance coverage and shall
provide proof of such coverage to Allegiance upon Allegiance's request. If
coverage is denied or reimbursement of a properly presented claim is disputed by
the carrier for insurance provided as described above, upon written request,
Lucent shall provide Allegiance with a certified copy of the involved insurance
policy or policies within ten (10) business days of receipt of such request. The
terms of this Section shall not be deemed to limit the liability of Lucent
hereunder, or to limit any rights Allegiance may have including, without
limitation, rights of indemnity or contribution.

                        ARTICLE 14 -- DISPUTE RESOLUTION

         14.1     PROJECT MANAGER LEVEL PERFORMANCE REVIEW. The applicable
Lucent Project Manager and Allegiance Project Manager shall meet as often as
shall reasonably be required to review the performance of the parties under the
applicable Product Addendum or Statement of Work and to resolve any disputes.
Written minutes of such meetings shall be kept by the parties. If these
representatives are unable to resolve a dispute within five (5) calendar days
after the initial request for a meeting, then the dispute shall be submitted to
an executive-level performance review as described in SECTION 14.2.

         14.2     EXECUTIVE LEVEL PERFORMANCE REVIEW. If the Project Manager
level performance review does not result in successful resolution of the
dispute, the appropriate executive officers of Allegiance and Lucent shall meet
in an effort to resolve the dispute. Written minutes of such meetings shall be
kept by the parties. If these representatives are unable to resolve the dispute
within five (5) calendar days after

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<PAGE>   48

the representatives have commenced negotiations, or ten (10) calendar days have
passed since the initial request for negotiations at this level, then the
dispute may be submitted to non-binding mediation in accordance with SECTION
14.3.

         14.3     VOLUNTARY, NON-BINDING MEDIATION. If executive-level
performance review does not result in successful resolution of the dispute, the
parties may, but shall not be obligated to, mutually agree in writing to submit
the dispute to non-binding mediation. Mediation must occur within thirty (30)
calendar days after the parties agree to submit the dispute to mediation, and
the duration of the mediation shall be limited to two (2) business days. The
parties mutually shall select an independent mediator experienced in commercial
contract telecommunications disputes, and each shall designate a
representative(s) to meet with the mediator in good faith in an effort to
resolve the dispute. The specific format for the mediation shall be left to the
discretion of the mediator and the designated party representatives and may
include the preparation of agreed-upon statements of fact or written statements
of position furnished to the other party.

         14.4     CONTINUED PERFORMANCE. Unless continued performance is clearly
impractical due to the issue in dispute, both parties shall continue performing
their obligations under this Agreement and the applicable Product Addendum(s)
and Statement(s) of Work while the dispute is being resolved under this Article
unless and until the dispute is resolved or until this Agreement is terminated
as provided herein.

         14.5     EQUITABLE RELIEF. Notwithstanding anything contained in this
Agreement to the contrary, the parties shall be entitled to seek injunctive or
other equitable relief whenever the facts or circumstances would permit a party
to seek such equitable relief in a court of competent jurisdiction.

                           ARTICLE 15 -- MISCELLANEOUS

         15.1     NOTICES. Any written notice required or permitted to be
delivered pursuant to this Agreement shall be in writing and shall be deemed
delivered: (a) upon delivery if delivered in person; (b) three (3) business days
after deposit in the United States mail, registered or certified mail, return
receipt requested, postage prepaid; (c) upon transmission if sent via
telecopier, with a confirmation copy sent via overnight mail, provided that
confirmation of such overnight delivery is received by the sender; (d) one (1)
business day after deposit with a national overnight courier, provided that
confirmation of such overnight delivery is received by the sender; (e) upon
transmission if sent via e-mail, with a confirmation copy sent via telecopier
same day, in each case addressed to the following addresses:

<TABLE>

<S>                                                       <C>
         If to Allegiance:                                 If to Lucent:

         Allegiance Telecom, Inc.                          Lucent Technologies Inc.
         1950 Stemmons Freeway                             4851 LBJ Freeway
         Suite 3026                                        Suite 900
         Dallas, Texas  75207                              Dallas, Texas  75244
         Attention:  President & Chief Operating Officer   Attention:  Mikki Cooper
         Telecopier: 214/261-7107                          Telecopier: 972/858-4718
         E-mail:  dan.yost@algx.com                        E-mail: macooper@lucent.com

         With a copy to:                                   With a copy to:

         Allegiance Telecom, Inc.                          Lucent Technologies
         4 Westbrook Corporate Center                      1750 East Golf Road
         Suite 400                                         Schaumburg, IL  60137
</TABLE>

                                -40-                                CONFIDENTIAL

<PAGE>   49

<TABLE>

<S>                                                       <C>
         Westchester, Illinois  60154                      Attention:  Alexandra Darrow
         Attention:  General Counsel                       Telecopier:  847/290-4854
         Telecopier: 708/836-5250                          E-mail:  adarrow@lucent.com
         E-mail:  mark.tresnowski@algx.com
</TABLE>

or to such other address as may be specified by either party hereto upon notice
given to the other.

         15.2     BANKRUPTCY. If Lucent voluntarily or involuntarily becomes
subject to the protection of the Bankruptcy Code and Lucent or the trustee in
bankruptcy rejects this Agreement under Section 365 of the Bankruptcy Code,
Allegiance shall have the right to: (a) treat this Agreement as terminated; or
(b) retain Allegiance's rights under this Agreement, specifically including,
without limitation, the right to exercise its rights granted herein to the
Software (and to all work-in-progress relating thereto). Failure by Allegiance
to assert its right to retain its benefits to the intellectual property embodied
in the Software pursuant to Section 365(n)(1)(B) of the Bankruptcy Code with
respect to an executory contract rejected by Lucent or the trustee in bankruptcy
shall not be construed by the courts as a termination of such contract by
Allegiance under Section 365(n)(1)(A) of the Bankruptcy Code.

         15.3     APPROVAL OF SUBCONTRACTORS. Except as to providers of Embedded
Third Party Software, Lucent shall obtain Allegiance's written consent, which
Allegiance may withhold in it sole discretion, before entering into agreements
with any subcontractors who may supply any part of any Products or Services to
Allegiance. At Allegiance's request, Lucent shall provide information regarding
the subcontractors' qualifications and a listing of the subcontractors' key
personnel. Lucent shall indemnify Allegiance for the actions or omissions of its
subcontractors under the terms and conditions specified in SECTION 13.1. All
subcontractors and their representatives, agents and employees must sign a
confidentiality and non-disclosure agreement containing terms substantially
similar to those set forth in this Agreement protecting Allegiance's
Confidential Information prior to and as a condition of becoming an authorized
subcontractor.

         15.4     FORCE MAJEURE. Each party shall be excused from performing any
of its obligations hereunder, in whole or in part, as a result of delays caused
by the other party or a Third Party or by an act of God, war, riot, civil
commotion, explosion, fire, government action, court order, epidemic, organized
labor or other organized union-related activities that affect manufacturing of
the Product(s) or other circumstance beyond its reasonable control, but
specifically excluding Lucent organized labor and/or Lucent organized
union-related activities that affect installation of the Product(s) and the
non-performance of any Lucent subcontractor, regardless of cause. If any of the
above-enumerated circumstances prevent, hinder or delay performance of either
party's obligations hereunder for more than thirty (30) calendar days, the party
not prevented from performing shall have the right to terminate the affected
Procurement Document(s) without liability or penalty as of the date specified by
such party in a written notice of termination to the other party.

         15.5     BINDING NATURE AND ASSIGNMENT. Subject to all other provisions
herein contained, this Agreement shall be binding on the parties and their
successors and permitted assigns. Except as provided in this Section, neither
party shall assign or otherwise transfer this Agreement, or any part hereof, nor
delegate any of its duties hereunder, to any Third Party without the prior
written consent of the other party (including, in the case of Allegiance, by a
Vice-President or higher-level officer of Allegiance). Allegiance shall have the
right to assign this Agreement to any Affiliate at any time upon written notice
to Lucent. In addition to the foregoing, Allegiance shall have the right to
pledge as collateral to its lenders all of Allegiance's rights under this
Agreement and its interests in any Products acquired hereunder. Any rights
granted to Allegiance under this Agreement to use the Products and Documentation
shall inure to

                                -41-                                CONFIDENTIAL

<PAGE>   50

the benefit of any acquirer of, or successor in interest to, Allegiance, whether
by merger, consolidation, purchase, operation of law or otherwise.

         15.6     MEDIA RELEASES AND PUBLIC DISCLOSURES OF AGREEMENT. Without
the prior written consent of the other party (which for Allegiance shall be a
Vice-President or higher-level officer of Allegiance), neither party shall issue
or release any statement, article, advertisement, public or private announcement
(including, without limitation, any announcement made via e-mail or any posting
on the Internet or World Wide Web), media release or other similar publicity
relating in any manner to: (a) any aspect of this Agreement, including
Procurement Documents; (b) any aspect of any Product or Services; or (c) the
fact that the parties have engaged in any discussions or negotiations regarding
any of the foregoing. Neither party shall use the name or any trademark or logo
of the other party without the prior written consent of the other party. With
respect to private announcements only, Lucent shall be permitted to make
internal reports to the extent such announcement is made solely within Lucent
for Lucent's internal business reporting purposes in the ordinary course of
business provided such announcement is accompanied by a conspicuous statement
that such announcement constitutes the Confidential Information of "Allegiance
Telecom, Inc." and shall not be disclosed to any Third Parties. Notwithstanding
the foregoing, the parties will create a press release as mutually agreed by the
parties to announce the formation of the Allegiance and Lucent relationship.

         15.7     COUNTERPARTS. This Agreement, any Product Addendum and any
Statement of Work may be executed in one (1) or more duplicate originals, all of
which together shall be deemed one and the same instrument.

         15.8     SEVERABILITY. If any provision of this Agreement or any
Product Addendum or Statement of Work is found by a court of competent
jurisdiction to be invalid or unenforceable, such invalidity or unenforceability
shall not invalidate or render unenforceable any other part of this Agreement or
any Product Addendum or Statement of Work, but the Agreement, Product Addendum
and/or Statement of Work shall be construed as not containing the particular
provision or provisions held to be invalid or unenforceable.

         15.9     WAIVER. No delay or omission by either party hereto to
exercise any right occurring upon any noncompliance or default by the other
party with respect to any of the terms of this Agreement shall impair any such
right or power or be construed to be a waiver thereof. A waiver by either of the
parties hereto of any of the covenants, conditions or agreements to be performed
by the other shall not be construed to be a waiver of any succeeding breach
thereof or of any covenant, condition or agreement herein contained.

         15.10    GOVERNING LAW; EXCLUSIVE JURISDICTION. This Agreement, and all
the rights and duties of the parties arising from or relating in any way to the
subject matter of this Agreement or the transaction(s) contemplated by it, shall
be governed by, construed and enforced in accordance with the law of the State
of Illinois (excluding any conflict of laws provisions of the State of Illinois
that would refer to and apply the substantive laws of another jurisdiction). Any
suit or proceeding relating to this Agreement, including arbitration
proceedings, shall be brought only in Cook County, Illinois. EACH OF THE PARTIES
CONSENT TO THE EXCLUSIVE PERSONAL JURISDICTION AND VENUE OF THE STATE AND
FEDERAL COURTS LOCATED IN COOK COUNTY, ILLINOIS.

         15.11    COMPLIANCE WITH REGULATIONS.

                  15.11.1 RADIO FREQUENCY ENERGY STANDARDS. Products furnished
         under this Agreement or any Product Addendum or Statement of Work for
         installation within the United States shall, at

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<PAGE>   51

         the time of installation, comply to the extent applicable with the
         requirements of Part 15, Subpart J, and all other applicable Rules and
         Regulations of the Federal Communications Commission including, without
         limitation, those sections relating to the labeling of product(s) and
         the suppression of radio frequencies and electromagnetic radiation to
         specified levels. Product(s) furnished under this Agreement and/or any
         Product Addendum or Statement of Work for installation outside the
         United States shall comply with all local governmental regulations, as
         applicable.

                  15.11.2 REGISTRATION. Products furnished under this Agreement
         and/or any Product Addendum or Statement of Work for installation
         within the United States shall, at the time of installation, comply to
         the extent applicable with the requirements of Part 68 of the Federal
         Communications Commission's Rules and Regulations including, without
         limitation, all labeling and customer instruction requirements.
         Products furnished under this Agreement and/or any Product Addendum or
         Statement of Work for installation outside the United States shall
         comply with all local governmental regulations, as applicable.

                  15.11.3 OTHER. Each party shall comply with all applicable
         laws, ordinances, regulations and codes including, without limitation,
         procurement of all required permits or certifications, in connection
         with its performance under this Agreement and/or any Product Addendum
         or Statement of Work.

         15.12    NO CONSTRUCTION AGAINST DRAFTER. The parties agree that any
principle of construction or rule of law that provides that an agreement shall
be construed against the drafter of the agreement in the event of any
inconsistency or ambiguity in such agreement shall not apply to the terms and
conditions of this Agreement.

         15.13    RELATIONSHIP OF PARTIES. The parties acknowledge that they are
independent contractors, and nothing set forth in this Agreement shall be deemed
or construed to render the parties as joint venturers, partners or employer and
employee. Under no circumstances shall Allegiance be considered the employer of
any Lucent personnel, nor shall Lucent have any right with respect to any
employee of Allegiance.

         15.14    INTERNATIONAL PROVISIONS.

                  15.14.1 COMPLIANCE WITH EXPORT REGULATIONS. The parties
         acknowledge that Products delivered and Services performed outside the
         United States may be subject to export control regulations of the U.S.
         and foreign governments, and the party exporting any such Products
         shall be responsible for compliance therewith. The parties shall
         cooperate with and assist each other in obtaining all export licenses
         or other written documentation, in accordance with applicable U.S. and
         foreign government regulations, that are necessary to enable the
         parties to perform their obligations under this Agreement. Allegiance
         shall provide to Lucent assurances and other export-related documents
         as may be required by the applicable U.S. governmental entities for
         Lucent to comply with U.S. export regulations. Each Procurement
         Document may, if applicable, set forth the export control
         classification numbers for each Product covered thereunder. To the
         extent the applicable export control classification number is not
         provided therein, Lucent shall, upon Allegiance's request, timely
         provide Allegiance with the export control classification numbers for
         the applicable Products.

                  15.14.2 SERVICES PERFORMED OUTSIDE THE UNITED STATES. Except
         as set forth in this Section or in a Product Addendum or Statement of
         Work, Services performed outside the United States shall be treated the
         same as performance of Services within the United States, and all

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<PAGE>   52

* NOTE: CERTAIN MATERIAL HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL
TREATMENT AND SUCH MATERIAL HAS BEEN FILED SEPARATELY WITH THE SEC.

         applicable provisions of this Agreement shall apply to such Services
         with full force and effect. If Lucent Agrees to perform Services
         outside the United States that require United States government
         licenses, permits, authorizations and/or other clearances
         (collectively, "CLEARANCES"), Lucent or its Affiliates shall obtain and
         maintain all such Clearances. Lucent or its Affiliates shall cooperate
         with and assist Allegiance in obtaining all additional Clearances
         required for completion of Allegiance's objectives as set forth in this
         Agreement. If Lucent or its Affiliates are denied any necessary
         Clearances or such Clearances are withdrawn or revoked, Lucent may
         terminate its performance with respect to the affected international
         Services without additional liability to Allegiance.

                  15.14.3 U.S. FOREIGN CORRUPT PRACTICES ACT AND OTHER LAWS.
         With respect to each party's performance under this Agreement, neither
         party shall, by or through its Affiliates, agents, employees,
         representatives or otherwise, take any action in violation of the
         United States Foreign Corrupt Practices Act and shall make no payment
         or transfer anything of value, directly or indirectly, to any employee
         of a government or instrumentality thereof, international organization,
         political party or official or candidate thereof, to influence any
         decision to obtain or retain business or secure other advantage.
         Neither party shall, by or through its Affiliates, agents, employees,
         representatives or otherwise, knowingly commit any other act or omit to
         take action which is unlawful under the boycott provisions of the
         Export Administration Act, the Internal Revenue Code or, to the extent
         not inconsistent with the laws of the United States, the laws of any
         other applicable jurisdiction.

                  15.14.4 LANGUAGE REQUIREMENTS. Documentation including,
         without limitation, any training Documentation, * Documentation or any
         human/machine readable *, shall be available to Allegiance, *, in the
         English language and, if generally made available to Lucent's
         customers, in the official language of those countries in which the
         applicable Product(s) are installed. In addition to the foregoing,
         Lucent shall provide such Documentation in such languages as Lucent
         generally makes available in the future or as may otherwise be agreed
         to by the parties in a Product Addendum or Statement of Work; provided,
         however, if development of such Documentation is undertaken pursuant to
         a Product Addendum or Statement of Work, Allegiance shall reimburse
         Lucent for the cost of such development until such time as Lucent makes
         such Documentation available to any customer of Lucent at which time
         Lucent shall provide to Allegiance a credit in the amount of all
         amounts paid by Allegiance for such development.

         15.15    ENTIRE AGREEMENT; MODIFICATION. This Agreement, together with
all of the Schedules, Exhibits (including Product Addenda and Statements of
Work), Attachments and Addenda hereto, sets forth the entire, final and
exclusive agreement between the parties as to the subject matter hereof and
supersedes all prior and contemporaneous agreements, understandings,
negotiations and discussions, whether oral or written, between the parties. This
Agreement may be modified only pursuant to a writing executed by authorized
representatives of Allegiance and Lucent. Lucent expressly agrees that all
amendments to this Agreement executed by Allegiance after the Effective Date
must be signed by a Vice President or higher-

                                -44-                                CONFIDENTIAL

<PAGE>   53

level officer of Allegiance in order to be effective and enforceable against
Allegiance. Lucent may rely on the representations made by Allegiance's
employees that such individuals have the Allegiance titles and/or hold the
Allegiance offices that are represented by such individuals. The parties
expressly disclaim the right to claim the enforceability or effectiveness of:
(a) any amendments to this Agreement that are not executed by an Allegiance
employee purporting to be a Vice President or higher-level officer of
Allegiance; (b) any oral modifications to this Agreement; and (c) any other
amendments that are based on course of dealing, waiver, reliance, estoppel or
other similar legal theory. The parties expressly disclaim the right to enforce
any rule of law that is contrary to the terms of this Section.

         IN WITNESS WHEREOF, authorized representatives of the parties have
executed this Master Procurement Agreement effective as of the date written
above.

ALLEGIANCE TELECOM, INC.                      LUCENT TECHNOLOGIES INC.

/s/ DANIEL YOST                               /s/ BILL PLUNKETT
-----------------------------------           ----------------------------------
Daniel Yost                                   Bill Plunkett
President & Chief Operating Officer           Senior Vice President Sales

                                -45-                                CONFIDENTIAL

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