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                                                                    Exhibit 10.8

                           NETWORK SERVICES AGREEMENT

                                 by and between

                              AMERICA ONLINE, INC.

                                       and

                                 BBN CORPORATION

                        Effective as of December 31, 1999
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                                TABLE OF CONTENTS
                                -----------------

MASTER AGREEMENT

1.    BACKGROUND, OBJECTIVES AND WAIVER........................................1
   1.1.     Background and Objectives..........................................1
   1.2.     Termination of Original Agreement; Waiver..........................1

2.    TERM.....................................................................2

3.    PROVISION OF SERVICES....................................................2
   3.1.     General............................................................2
   3.2.     Resale of Dedicated Resources......................................3
   3.3.     Sale of Vendor Network.............................................3

4.    ORDERING.................................................................3
   4.1.     General............................................................3
   4.2.     Order Tracking.....................................................3

5.    ACCEPTANCE TESTING AND FINAL ACCEPTANCE..................................4

6.    PROPRIETARY RIGHTS.......................................................4
   6.1.     Ownership of Proprietary Information...............................4
   6.2.     Ownership of Vendor Network........................................4
   6.3.     Telephone Numbers..................................................4

7.    SERVICE LEVELS...........................................................4

8.    CHARGES AND TAXES........................................................5
   8.1.     General............................................................5
   8.2.     Taxes..............................................................5
   8.3.     Certain Obligations Corresponding to the Waiver....................6

9.    INVOICING AND PAYMENT....................................................6
   9.1.     Invoicing..........................................................6
   9.2.     Payment Due........................................................7
   9.3.     Accountability.....................................................7
   9.4.     Disputed Charges...................................................8

10.   AUDIT....................................................................8
   10.1.    Audit Rights.......................................................8
   10.2.    Records Retention..................................................8

11.   CONFIDENTIALITY..........................................................8
   11.1.    Confidential Information...........................................8
   11.2.    Obligations........................................................8
   11.3.    Exclusions.........................................................9
   11.4.    Residual Knowledge................................................10
   11.5.    Customer Data.....................................................10

12.   REPRESENTATIONS, WARRANTIES AND COVENANTS...............................10
   12.1.    Compliance with Specifications and Applicable Laws................10
   12.2.    Non-Infringement..................................................10
   12.3.    Technology........................................................10
   12.4.    Year 2000.........................................................11

13.   TERMINATION.............................................................12
   13.1.    Termination of Master Agreement for Cause.........................12


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   13.2.    No Implication Against Materiality................................13
   13.3.    Termination for Change of Control.................................13
   13.4.    Termination/Expiration Assistance; Transition Period..............14

14.   LIABILITY AND FORCE MAJEURE.............................................14
   14.1.    Liability Restrictions............................................14
   14.2.    Force Majeure.....................................................14

15.   INDEMNIFICATION.........................................................15

16.   GENERAL.................................................................15
   16.1.    Binding Nature and Assignment.....................................15
   16.2.    Continued Performance and Governing Law...........................16
   16.3.    Entire Agreement..................................................16
   16.4.    Notices...........................................................16
   16.5.    Counterparts......................................................17
   16.6.    Relationship of Parties...........................................17
   16.7.    Severability......................................................17
   16.8.    Waiver of Default.................................................18
   16.9.    Cumulative Remedies...............................................18
   16.10.   Survival..........................................................18
   16.11.   Publicity.........................................................18
   16.12.   Certain Regulatory Events.........................................18
   16.13.   Amendment.........................................................19
   16.14.   Incorporation by Reference........................................19
   16.15.   Construction......................................................20



SCHEDULE A  Definitions......................................................A-1

SCHEDULE B  Dial-Up Access Services, Service Levels, Pricing and
            Other Terms......................................................B-1

SCHEDULE C  Broadband Backhaul Services, Service Levels, Pricing
            and Other Terms..................................................C-1

SCHEDULE D  Other Services...................................................D-1


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                           NETWORK SERVICES AGREEMENT

This Network Services Agreement (together with the attached Schedules and
Exhibits, the "Agreement"), effective as of December 31, 1999 (the "Effective
Date"), is entered into by and between America Online, Inc., a Delaware
corporation with offices located at 22000 AOL Way, Dulles, VA 20166
("Customer"), and BBN Corporation, a Massachusetts corporation, with offices
located at 3 Van de Graaff Drive, Burlington, MA 01803 ("Vendor"). As used in
this Agreement, "Party" means either Customer or Vendor, as appropriate, and
"Parties" means Customer and Vendor. The Parties agree that the following terms
and conditions shall apply to the products and services to be provided by Vendor
under this Agreement in consideration of certain payments to be made by
Customer. Defined terms used but not defined in the body of this Master
Agreement or the Schedules (other than Schedule A) shall have the meanings given
such terms in Schedule A.

1.   BACKGROUND, OBJECTIVES AND WAIVER

     1.1. Background and Objectives.
          -------------------------

          This Agreement is being made and entered into with reference to the
          following:

          (a)  Customer is an interactive service provider that desires to
               purchase (i) fully managed, end-to-end dial-up access services,
               and (ii) certain broadband backhaul services.

          (b)  Customer and Vendor previously contracted for Vendor to provide
               certain dial-up access services in that certain BBN-AOL Dial-Up
               Network Services Agreement dated September 23, 1996, as amended
               by (i) that certain BBN-AOL Dial-Up Network Services Agreement
               Amendment 1, dated April 29, 1997, (ii) that certain BBN-AOL
               Dial-Up Network Services Agreement Amendment 2, dated September
               29, 1997, (iii) that certain BBN-AOL Dial-Up Network Services
               Agreement Amendment 3, dated January 29, 1998, (iv) that certain
               BBN-AOL Dial-Up Network Services Agreement Amendment 4, dated
               February 11, 1998, (v) that certain BBN-AOL Dial-Up Network
               Services Agreement Amendment 5, dated June 30, 1998 and (vi) that
               certain BBN-AOL Dial-Up Network Services Agreement Amendment 6,
               dated July 28, 1999 (such agreement as amended, the "Original
               Agreement").

     1.2. Termination of Original Agreement; Waiver.

          (a)  The Original Agreement is hereby terminated as of the Effective
               Date. Except to the extent otherwise provided in this Agreement,
               the obligations of the Parties arising under the Original
               Agreement before the Effective Date of this Agreement shall be
               governed by the Original Agreement. The obligations of the
               Parties arising after the Effective Date (including with respect
               to Vendor's provision of Services during the Term) shall be
               governed by this Agreement.

          (b)  As partial consideration for entering into this Agreement, for
               the respective waivers and releases set forth below (collectively
               the "Waiver"), and for Vendor's obligations set forth in Section
               8.3 of this Master Agreement, each

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               Party hereby irrevocably waives and releases all claims, torts,
               liabilities, debts, suits, demands, causes of action, actions and
               rights, whether known, unknown, contingent or fixed, against the
               other Party and its respective predecessors, current and former
               Affiliates, successors, assigns, attorneys, directors, officers,
               agents and employees arising from or pertaining to the Original
               Agreement; provided, however, that:

               (i)  nothing contained in the Waiver shall release the Parties
                    from their respective obligations under this Agreement
                    (including with respect to the installed Dedicated Dial-Up
                    Access Ports previously provided under the Original
                    Agreement that Vendor is obligated to continue to provide
                    pursuant to Schedule B of this Agreement); and

               (ii) nothing contained in the Waiver shall apply to disputes or
                    any other matters between the Parties under this Agreement,
                    or based upon or associated with the claims of unaffiliated
                    third parties arising under the Original Agreement or this
                    Agreement.

2.   TERM


     The term of the Master Agreement shall begin on the Effective Date and
     shall expire on December 31, 2006, unless terminated earlier in accordance
     with the Agreement or extended pursuant to the relevant section in the
     appropriate Schedule or otherwise by mutual written agreement (such period,
     as terminated earlier or so extended, the "Term"). Each Schedule to the
     Agreement shall be effective for the period of time during the Term set
     forth in such Schedule.

3.   PROVISION OF SERVICES

     3.1. General.
          -------

          (a)  This Agreement sets forth the terms and conditions under which
               Customer may purchase Services from Vendor. Customer may utilize
               the Services purchased hereunder for any lawful purpose including
               in connection with any service or product offering made available
               by Customer or its Special Affiliates during the Term, providing
               access to an AOL Information Service, providing the delivery of
               Internet access or providing other subscriber-related services to
               end-users. The Parties acknowledge that this Agreement does not:
               (a) grant to Vendor an exclusive privilege to sell or otherwise
               provide to Customer any products or services, or (b) except as
               otherwise provided by Section 3.2 of the Master Agreement, or as
               otherwise required by this Master Agreement or any of the
               Schedules, restrict Vendor from providing products or services to
               other customers of Vendor. Customer may contract with other
               suppliers for the procurement of any products or services.

          (b)  Customer shall (i) remain the single point-of-contact with Vendor
               with respect to those Services provided to Special Affiliates
               pursuant to this Agreement, including with respect to any claims,
               disputes or other actions that Special Affiliates desire to make
               against Vendor, (ii) remain obligated to perform its

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               payment obligations under the Agreement with respect to those
               Services provided by Vendor to Special Affiliates pursuant to
               this Agreement, and (iii) Customer agrees to indemnify and hold
               Vendor harmless for claims brought against Vendor by Special
               Affiliates associated with the Services provided by Vendor to
               Special Affiliates pursuant to this Agreement; provided, however,
               that nothing herein applies to claims brought directly by
               Customer for damages arising out of Services utilized by Special
               Affiliates. For purposes of the Agreement, Services provided to
               Special Affiliates pursuant to this Agreement shall be deemed to
               be Services provided to Customer.

     3.2. Resale of Dedicated Resources.
          -----------------------------

          Except as specifically set forth in Schedule B with respect to the
          Dedicated Dial-Up Services, Vendor shall not resell or offer to resell
          any dedicated Services ordered and accepted by Customer regardless of
          whether or not such Services are utilized by Customer.

     3.3. Sale of Vendor Network.
          ----------------------

     (a)  Notwithstanding anything to the contrary in this Agreement, Customer
          shall have the right of first refusal with respect to any sale or
          transfer other than to a Vendor Affiliate of any unit or division that
          has, as its primary business, the provision of Dedicated Dial-Up
          Access Services to Customer and has Dedicated Dial-Up Access Ports to
          Customer; provided, however, in no event shall Customer have such
          right of first refusal in connection with (i) the sale or transfer of
          a business unit that does not relate to the provision of Services to
          Customer or (ii) the sale or transfer of any Vendor assets to any
          entity created as a result of, or arising out of, the closing of the
          proposed merger of GTE Corporation and Bell Atlantic Corporation so
          long as the management of Vendor continues to have primary management
          responsibility of the new entity; provided further, however, that any
          transaction in which any assets of Vendor are transferred back to any
          Affiliate of the combined GTE/Bell Atlantic corporation shall not be
          covered by this Section.

4.   ORDERING

     4.1. General.
          -------

          The ordering of Services by Customer and the delivery of such Services
          by Vendor shall be governed by the terms and conditions set forth in
          the applicable Schedule of this Agreement corresponding to such
          Services.

     4.2. Order Tracking.
          --------------

          Vendor will provide Customer with weekly information on Orders as
          reasonably requested by Customer in a format consistent with that
          provided under the Original Agreement immediately prior to the
          Effective Date of this Agreement. Vendor will provide Customer with
          written reports relating to Orders as mutually agreed upon by the
          Parties.

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5.   ACCEPTANCE TESTING AND FINAL ACCEPTANCE

     Acceptance testing provisions associated with the Services are set forth in
     the applicable Schedule for such Services.

6.   PROPRIETARY RIGHTS

     6.1. Ownership of Proprietary Information.
          ------------------------------------

          (a)  All right, title and interest in Customer developed software and
               other Customer proprietary information (including any Customer
               software or Customer proprietary information which may be
               incorporated into written material or software delivered under
               this Agreement), including all intellectual property rights
               related thereto, will remain in Customer. Customer shall also
               have all ownership rights, including copyright, to all written
               reports prepared and delivered to Customer by Vendor under this
               Agreement.

          (b)  All right, title and interest in Vendor developed software and
               other Vendor proprietary information, including all intellectual
               property rights related thereto, will remain in Vendor; provided,
               however, any software developed by Vendor incidental to the
               performance of Services for Customer, the cost of which is
               separately charged to, and reimbursed by, Customer shall be
               jointly owned by Vendor and Customer, with no duty of accounting.

          (c)  All right, title and interest in software jointly developed by
               the Parties shall be jointly owned by Vendor and Customer, with
               no duty of accounting.

          (d)  With respect to Subsections (b) and (c) above, each Party hereby
               agrees to take all actions, and execute and deliver such
               documentation as is necessary to evidence the other Party's
               ownership interest in and to the developed Software.

          (e)  Each Party hereby grants to the other Party a limited license to
               utilize each other's software and other proprietary information
               in connection with Vendor's performance of, and Customer's
               receipt of, the Services.

     6.2. Ownership of Vendor Network.
          ---------------------------

          Except to the extent that Customer owns or has rights in certain
          equipment used to provide Dedicated Dial-Up Access Ports as of the
          Effective Date, or purchases Vendor Network assets pursuant to Section
          3.3 of the Master Agreement, Vendor retains title and ownership to the
          Vendor Network.

     6.3. Telephone Numbers.
          -----------------

          As between Vendor and Customer, Customer shall have title and
          ownership to all telephone numbers used to provide Dial-Up Access
          Services.

7.   SERVICE LEVELS

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     All Services provided by Vendor shall comply with the applicable Service
Levels.

8.   CHARGES AND TAXES

     8.1. General.
          -------

          Charges for a Service hereunder shall not begin to accrue until after
          Final Acceptance of the Service. Charges for any Service shall be as
          computed pursuant to the Schedule of this Agreement corresponding to
          such Service. All charges specified in the Schedules fully compensate
          Vendor for Services. Customer will not be liable to Vendor for any
          charges not expressly set forth in the Schedules or the Master
          Agreement unless such charges are mutually agreed upon by the Parties
          in writing. Customer shall only be obligated to pay for Services
          provided in accordance with the terms of this Agreement.

     8.2. Taxes.
          -----

          The Parties' respective responsibilities for taxes arising under or in
          connection with this Agreement shall be as follows:

          (a)  Vendor shall be responsible for any sales, use, excise,
               value-added, services, consumption, and other taxes and duties
               payable by Vendor on any goods or services that are used or
               consumed by Vendor in providing the Services where the tax is
               imposed on Vendor's acquisition or use of such goods or services
               and the amount of tax is measured by Vendor's costs in acquiring
               such goods or services.

          (b)  Customer shall be responsible for any sales, use, excise,
               value-added, services, consumption, or other tax that is assessed
               on any particular Service received by Customer from Vendor.
               Customer shall also be responsible for any sales, use, excise,
               value-added or consumption taxes imposed on goods purchased by
               Customer from Vendor under the Agreement. If and to the extent
               any tax described in this Subsection (b) is reduced or eliminated
               during the Term, Vendor shall reduce or eliminate any charges for
               such taxes, as appropriate. If and to the extent any tax
               described in this Subsection (b) is increased during the Term, or
               a new tax is imposed upon any particular Service received by
               Customer from Vendor, then Customer shall have full
               responsibility for such increase or tax.

          (c)  The Parties agree to cooperate with each other to enable each to
               more accurately determine its own tax liability. Neither Party
               will act unreasonably in assisting the other Party in minimizing,
               to the extent legally permissible, such other Party's tax
               liability to the extent legally permissible. Each Party shall
               provide and make available to the other any resale certificates,
               information regarding out-of-state or out-of-country sales or use
               of equipment, materials or services, and other exemption
               certificates or information reasonably requested by either Party.

          (d)  Each Party shall promptly notify the other Party of, and
               coordinate with the other Party the response to and settlement
               of, any claim for taxes asserted by

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               applicable taxing authorities for which a Party is responsible
               hereunder, it being understood that with respect to any claim
               arising out of a form or return signed by a Party to this
               Agreement, such Party shall have the right to elect to control
               the response to and settlement of the claim, but the other Party
               shall have all rights to participate in the responses and
               settlements that are appropriate to its potential
               responsibilities or liabilities. If Customer requests Vendor to
               challenge the imposition of any tax, Customer shall reimburse
               Vendor for the reasonable legal fees and expenses it incurs.
               Customer shall be entitled to any tax refunds or rebates granted
               to the extent such refunds or rebates are of taxes that were paid
               by Customer, including taxes charged to Customer as Out-of-Pocket
               Expenses. Customer shall be responsible for interest and
               penalties incurred to the extent such interest and penalties are
               related to taxes paid or payable by Customer.

8.3. Certain Obligations Corresponding to the Waiver.
     -----------------------------------------------

     Promptly after execution of this Agreement, Customer shall pay to Vendor
     [*Material Omitted and Separately Filed Under an Application for
     Confidential Treatment] dollars ($[*Material Omitted and Separately Filed
     Under an Application for Confidential Treatment]) which amount represents
     an off-set of (i) the [*Material Omitted and Separately Filed Under an
     Application for Confidential Treatment] dollars ($[*Material Omitted and
     Separately Filed Under an Application for Confidential Treatment]) withheld
     by Customer under the Original Agreement and (ii) the [*Material Omitted
     and Separately Filed Under an Application for Confidential Treatment]
     dollars ($[*Material Omitted and Separately Filed Under an Application for
     Confidential Treatment]) that Vendor has agreed to pass-through to Customer
     from [*Material Omitted and Separately Filed Under an Application for
     Confidential Treatment] or its Affiliates for [*Material Omitted and
     Separately Filed Under an Application for Confidential Treatment]
     specifically affecting the Customer network in [*Material Omitted and
     Separately Filed Under an Application for Confidential Treatment].

9.   INVOICING AND PAYMENT

     9.1. Invoicing.
          ---------

          (a)  Vendor will invoice Customer for amounts due under this Agreement
               (including with respect to provision of Services to Special
               Affiliates) on a monthly basis in arrears. Each invoice shall
               contain the same information as provided under the Original
               Agreement immediately prior to the Effective Date of this
               Agreement, additional, similar information with respect to the
               Broadband Backhaul Services and Other Services, and any
               additional information as the Parties may otherwise agree. Each
               invoice will separately state those charges for the Dial-Up
               Access Services that are attributable to the provision of
               backhaul functions. Out-of-Pocket Expenses, if any, and Monthly
               Pass-Through Expenses will be billed monthly based upon actual
               and accrued costs, and such expenses shall be trued up on a
               quarterly basis. Upon any request by Customer, Vendor will
               provide Customer with access to books and records (including
               bills and invoices) from third party providers for all
               Out-of-Pocket Expenses and Monthly Pass-Through

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               Expenses. Any refunds or credits arising from an Out-of-Pocket
               Expense reimbursed by Customer or a Monthly Pass-Through Expense
               shall be remitted to Customer, and Vendor shall report and
               transmit to Customer any misdirected refunds or credits.

          (b)  To the extent a credit may be due Customer pursuant to this
               Agreement, Vendor shall provide Customer with an appropriate
               credit against amounts then due and owing; if no further payments
               are due to Vendor, Vendor shall pay such amounts to Customer
               within thirty (30) calendar days. In the event such payment is
               not made to Customer when due, Vendor will pay a late fee equal
               to the lesser of (a) one (1) percent of the amount of such
               charges per month; or (b) the maximum amount permissible by law.

          (c)  The detailed accounting of actual and accrued costs described in
               Section 3.D of the Original Agreement will be limited to costs
               incurred in the first quarter of Customer's fiscal year 2000 and
               the final true-up with respect to accrued costs (as described in
               the Original Agreement) will be completed and provided to
               Customer by March 31, 2000; and with respect to actual costs,
               Vendor will use all commercially reasonable efforts to work with
               its providers to reconcile actual costs as soon as reasonably
               practicable. Subject to Section 8.3 of this Master Agreement and
               to the last sentence of Section 8.1(a)(i) of Schedule B, Vendor
               will invoice Customer for all amounts due under the Original
               Agreement as of the Effective Date, and Customer will pay to
               Vendor such amounts due, in accordance with Section 9.2 of this
               Master Agreement.

9.2. Payment Due.
     -----------

     Subject to the other provisions of this Article 9, all undisputed charges
     shall be due and payable by Customer within thirty (30) calendar days after
     receipt of a proper invoice for such amount. In the event that any such
     charges are not received by Vendor within five (5) business days after
     receipt by Customer of written notice from Vendor indicating that such
     charges have not been paid within such thirty-day period, then commencing
     as of the original due date, Customer will pay a late fee equal to the
     lesser of (a) one (1) percent of the amount of such charges per month; or
     (b) the maximum amount permissible by law. All undisputed amounts due and
     payable to Vendor under this Article 9 shall be paid, at Customer's option,
     either (i) by check payable to the order of Vendor or (ii) by electronic
     funds transfer to Vendor from account(s) designated by Customer.

9.3. Accountability.
     --------------

     Both Parties shall maintain complete and accurate records of and supporting
     documentation for the amounts billable or owed and credits applicable to
     either Party under the terms of this Agreement, in accordance with
     generally accepted accounting principles applied on a consistent basis.
     Both Parties agree to provide the other Party with documentation and other
     information with respect to any amount claimed or owed as may be reasonably
     requested by either Party to verify accuracy and compliance with the
     provisions of this Agreement.

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9.4. Disputed Charges.
     ----------------

     Customer shall pay undisputed charges when such payments are due under this
     Article 9. Customer may withhold payment of particular charges that
     Customer disputes in good faith. To the extent that Vendor is entitled to
     such payment withheld pursuant to resolution of the underlying dispute,
     Customer shall pay to Vendor such payments plus any interest accrued from
     the date such payments are withheld by Customer at a rate equal to one
     percent (1%) per month on the disputed amounts. Upon resolution of the
     dispute against Vendor, Vendor will pay Customer interest equal to one
     percent (1%) per month on the amounts overpaid or under-withheld by
     Customer.

10.  AUDIT

     10.1. Audit Rights.
           ------------

          Each Party, after reasonable notice, shall have the right to conduct
          reasonable audits of the other Party, through a third party
          independent auditor as selected by the Party conducting the audit or
          through any other mutually agreeable means, and subject to reasonable
          confidential requirements, to enforce a Party's rights and/or enforce
          the other Party's obligations under this Agreement.

     10.2. Records Retention.
           -----------------

          Until three (3) years after document creation, each Party will
          maintain, and provide to the other Party and its auditors access upon
          request to, records, documents and other information subject to audit
          under the Agreement.

11.  CONFIDENTIALITY

     11.1. Confidential Information.
           ------------------------

           Vendor and Customer each acknowledge that they may be furnished with,
           receive, or otherwise have access to Confidential Information (as
           defined below) of or concerning the other Party. As used in this
           Agreement and subject to Section 11.3 of the Master Agreement,
           "Confidential Information" means any information, in any form,
           furnished or made available directly or indirectly by one Party (the
           "Disclosing Party") to the other (the "Receiving Party") relating to
           or disclosed in the course of the negotiation or performance of this
           Agreement, that is, or should be reasonably understood to be,
           confidential or proprietary to the Disclosing Party, and shall
           include the material terms of this Agreement (including all
           information relating to prices and purchase commitments), invoices
           and any supporting information provided by Vendor or Customer with
           respect to such invoices, information audited pursuant to Article 10,
           all Customer Data, Customer's customer and member information,
           automatic number identification ("ANI") data and information, the
           relations of the Disclosing Party with its customers, employees and
           service providers, technical processes and formulas, source codes,
           product designs, sales, cost and other unpublished financial
           information, product and business plans, projections and marketing
           data.

     11.2. Obligations.
           -----------

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     (a)  Any proprietary rights in Confidential Information disclosed by a
          Party shall remain with such Party. Customer and Vendor shall only
          disclose Confidential Information of the other Party internally on a
          "need-to-know" basis. Customer and Vendor shall each use at least the
          same degree of care, but in any event no less than a reasonable degree
          of care, to prevent disclosing to third parties the Confidential
          Information of the other as it employs to avoid unauthorized
          disclosure, publication or dissemination of its own information of a
          similar nature; provided that a Party may disclose such information to
          an entity performing or receiving Services hereunder or to an
          independent third-party auditor on a "need-to-know" basis where (i)
          the provision or receipt of Services or audit by such entity is
          authorized under this Agreement, (ii) such disclosure is necessary or
          otherwise naturally occurs in that entity's scope of responsibility,
          and (iii) the entity agrees in writing to assume confidentiality
          restrictions no less stringent than those described in this Section
          11.2. Any disclosure to such entity shall be under the terms and
          conditions as provided herein.

     (b)  Each Party shall take reasonable steps to ensure that its employees,
          agents and to the extent applicable, third party auditors comply with
          this Article 11. In the event of any unauthorized disclosure or loss
          of, or inability to account for, any Confidential Information of the
          Disclosing Party, the Receiving Party shall promptly, at its own
          expense: (i) notify the Disclosing Party in writing; (ii) take such
          actions as may be necessary or reasonably requested by the Disclosing
          Party to minimize the violation; and (iii) cooperate in all reasonable
          respects with the Disclosing Party to minimize the violation and any
          damage resulting therefrom. With respect to any Confidential
          Information disclosed to the Receiving Party, the nondisclosure
          obligation shall last for five (5) years from the date of disclosure
          of such Confidential Information.

11.3. Exclusions.
      ----------

     (a)  "Confidential Information" shall exclude any particular information
          that (i) was, at the time of disclosure to it, lawfully in the public
          domain; (ii) after disclosure to it, is lawfully published or
          otherwise lawfully becomes part of the public domain through no fault
          of the Receiving Party; (iii) except for the material terms of the
          Agreement, was lawfully in the possession of the Receiving Party at
          the time of disclosure to it; (iv) was received after disclosure to it
          from a third party who had a lawful right to disclose such information
          to it without any obligation to restrict its further use or
          disclosure; and (v) was independently developed by the Receiving Party
          without reference to Confidential Information of the Disclosing Party.
          In addition, a Party shall not be considered to have breached its
          obligations by disclosing Confidential Information of the other Party
          to the minimum extent required to satisfy any legal requirement of a
          competent government body provided that, immediately upon receiving
          any such request and to the extent that it may legally do so, such
          Party advises the Disclosing Party promptly and prior to making such
          disclosure in order that the Disclosing Party may interpose an
          objection to such disclosure, take action to assure confidential
          handling of the Confidential Information, or take such other action as
          it deems appropriate to protect the Confidential Information.

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     (b)  Nothing in this Article 11 shall be construed or interpreted as a
          representation or agreement to restrict assignment or reassignment of
          a Party's employees. Subject to each Party's obligations under the
          Agreement, neither Party shall be precluded from participating in
          business activities that may be competitive with the other Party.

11.4. Residual Knowledge.
      ------------------

      Nothing contained in this Agreement shall restrict either Party from the
      use of any ideas, concepts, know-how, methodologies, processes,
      technologies, algorithms or techniques relating to the Services that
      either Party, individually or jointly, develops or discloses under this
      Agreement, provided that in doing so such Party does not breach its
      obligations under this Article or infringe the intellectual property
      rights of the other Party or third parties who have licensed or provided
      materials to such Party.

11.5. Customer Data.
      -------------

      (a)  Without limiting Vendor's obligations under Section 11.2 of the
           Master Agreement with respect to Customer Data, Vendor shall only use
           Customer Data to the extent necessary to fulfill its obligations
           under this Agreement.

      (b)  Vendor shall institute "standard industry practices" physical and
           logical security measures with respect to facilities and systems used
           to provide the Services, including with respect to any shared
           processing or network environments and with respect to the access and
           controls it affords to its employees, Affiliates and subcontractors
           (including the employees of each) to guard against, identify and
           promptly terminate the unauthorized access, alteration or destruction
           of Customer Data.

12.  REPRESENTATIONS, WARRANTIES AND COVENANTS

     12.1. Compliance with Specifications and Applicable Laws.
           --------------------------------------------------

           Vendor covenants that it shall perform the Services in accordance
           with the terms of this Agreement. Vendor represents that the Services
           offered to Customer are, and warrants that after the Effective Date
           Services purchased by Customer shall be, in conformance with
           applicable federal, state and local laws and regulations, including
           FCC requirements and specifications.

     12.2. Non-Infringement.
           ----------------

           Vendor warrants that the Services shall not knowingly infringe, and
           that Vendor shall perform its responsibilities under this Agreement
           in a manner that does not infringe, or constitute an infringement or
           misappropriation of, any patent, copyright, trademark, trade secret
           or other proprietary rights of Customer or any third party.

     12.3. Technology.
           ----------

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           Vendor covenants that in the event that Vendor provides any hardware
           and software upgrades as part of the Services, such upgrades shall be
           without additional charge to Customer. Vendor will implement software
           and hardware upgrades to the extent such upgrades are necessary to
           maintain the quality of Services as specified in this Agreement, stay
           consistent with industry standards and otherwise meet its obligation
           to provide Services hereunder.

     12.4. Year 2000.
           ---------

           Vendor represents that the Services offered to Customer are, and
           warrants that Services provided to Customer shall be, Year 2000
           Compliant. "Year 2000 Compliant" means that the Services satisfy the
           requirements set forth below:

           (a)  Limited Warranty. Vendor warrants that the Services will be Year
                ----------------
                2000 Compliant, pursuant to the terms of this Section 12.4
                (hereinafter referred to in this Section as the "Year 2000
                Compliance Limited Warranty"). Vendor warrants that in
                connection with Calendar-Related data and Calendar-Related
                processing of Date Data or of any System Date, the Services, as
                a whole or by its components, as to the Year 2000 will not
                malfunction, will not cease to function, will not generate
                incorrect data, will not produce incorrect results, and will
                represent dates without ambiguity when providing Calendar-
                Related data to and accepting Calendar-Related data from other
                automated, computerized, and/or software systems and users via
                use interfaces, electronic interfaces, and data storage.

                In the event of any Year 2000 Noncompliance with respect to the
                Services when and as specified herein, Vendor shall, as
                Customer's sole and exclusive remedy, repair or replace the
                affected Services within a reasonable period of time as
                determined by the severity of the failure and the level of
                effort necessary to correct such failure.

                Vendor shall meet the obligations set forth in this Year 2000
                Compliance Limited Warranty provided that all Customer or third
                party supplied computer software, computer firmware, and
                computer hardware that directly interface with the Services, co-
                exist with the Services, or directly influence the Services'
                operation, are also demonstrated to comply with this Year 2000
                Compliance Limited Warranty.

          (b)   Disclaimer. Except as provided by this Year 2000 Compliance
                ----------
                Limited Warranty, Vendor shall not be liable for any failure of
                the AOLnet to be Year 2000 Compliant.

          (c)   Definitions. For the purposes of this Year 2000 Compliance
                -----------
                Limited Warranty, the following defined terms shall have the
                following meanings:

                (i)   "AOLnet" means that portion of the Customer network in the
                      United States, which is managed by Vendor. "AOLnet" does
                      not include equipment, telephone circuits, networks,
                      network equipment, or telephone circuits not owned or
                      controlled by Vendor.

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<PAGE>

          (ii)  "Calendar-Related" refers to date values based on the Gregorian
                calendar, which includes Leap Years, and to all uses in any
                manner of those date values, including without limitation,
                manipulations calculations, conversions, comparisons, and
                presentation.

          (iii) "Date Data" means any Calendar-Related data the inclusive range
                January 1, 1900 through December 31, 2035, which the Services
                uses in any manner.

          (iv)  "System Date" means any Calendar-Related data value in the
                inclusive range January 1, 1985 through December 31, 2035
                (including the natural transition between such values), which
                the Services shall be able to use as its current date while
                operating.

          (v)   "Year 2000" Noncompliance" means any failure of the Services to
                be Year 2000 Compliant.

13.  TERMINATION

     13.1. Termination of Master Agreement for Cause.
           -----------------------------------------

           (a)  Customer's Right to Terminate. In addition to any other rights
                -----------------------------
                or remedies to which Customer may be entitled under this
                Agreement, in the event that:

                (i)   Vendor commits a material breach of this Agreement, which
                      breach is not cured within thirty (30) calendar days after
                      notice of breach from Customer to Vendor;

                (ii)  Vendor commits repeated material breaches of this
                      Agreement, even if cured;

                (iii) Vendor violates either Section 3.2 (Resale of Dedicated
                      Resources) or Vendor's core obligations with respect to
                      the most-favored customer provisions set forth in the
                      Schedules (e.g., Section 8.3(b) of Schedule B); or

                (iv)  there is a total or near-total outage of any of the
                      Services that, while it may last fewer than thirty (30)
                      calendar days, is widespread and prolonged enough to
                      justify a reasonable person, considering all relevant
                      industry standards, to terminate the Agreement,


                then Customer may, at its option and in its sole discretion,
                exercise the Agreement Termination Right for cause; provided,
                however, if Customer's termination for cause right is solely
                related to the Other Services, Customer may only exercise the
                Agreement Termination Right with respect to the Other Services.
                In the event of a termination of Customer's obligations with
                respect to the Purchase Commitments as a result of termination
                of the Agreement or any Schedule, Customer shall have no further
                liability to Vendor with respect to such

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                       CONFIDENTIAL TREATMENT REQUESTED

          Purchase Commitments. To the extent new services are added to this
          Agreement, defaults will be as specified therein.

     (b)  Vendor's Right to Terminate. In addition to any other rights or
          ---------------------------
          remedies to which Vendor may be entitled under this Agreement, in the
          event that

          (i)  Customer commits a material breach of this Agreement, including
               non-payment of undisputed amounts due and owing to Vendor in
               accordance with the terms of this Agreement, which breach is not
               cured within thirty (30) calendar days after notice of breach
               from Vendor to Customer; or

          (ii) Customer fails to meet its obligations with respect to the
               Purchase Commitments in accordance with and subject to the terms
               of this Agreement, which failure is not cured within thirty (30)
               calendar days after notice of failure from Vendor to Customer;
               provided, however, Customer shall be deemed not to have failed to
               meet its Purchase Commitments if it pays Vendor such amounts that
               Customer would have otherwise had to pay if Customer actually met
               such Purchase Commitments,

          then Vendor, at its option and in its sole discretion, may terminate
          this Agreement; provided, however, if Vendor's termination for cause
          right is solely related to the Other Services, Vendor may only
          exercise the Agreement Termination Right with respect to the Other
          Services. To the extent new services are added to this Agreement,
          defaults will be as specified therein.

13.2. No Implication Against Materiality.
      ----------------------------------

      The inclusion of any provision, obligation or duty in Section 13.1, or any
      statement in this Agreement, that a particular provision, obligation or
      duty is "material" shall not be construed to imply that any other
      provision, obligation or duty in this Agreement is not material.

13.3. Termination for Change of Control.
      ---------------------------------

      In the event of (a) a change in control of Vendor where such control is
      acquired, directly or indirectly, in a single transaction or series of
      related transactions, (b) all or substantially all of the assets of Vendor
      are acquired by or transferred to any entity, or (c) Vendor is merged with
      or into another entity to form a new entity, then at any time after any
      such event, Customer may, at its option and in its sole discretion,
      exercise the Agreement Termination Right; provided, however, nothing in
      this Section shall apply in a change in control resulting from or arising
      out of the closing of the proposed merger of GTE Corporation and Bell
      Atlantic Corporation (including any transaction in which any assets of
      Vendor are transferred back to any Affiliate of the combined GTE/Bell
      Atlantic corporation), unless the acquirer or merged entity is (i) a
      Significant Competitor of Customer (as such list of Significant
      Competitors may be modified from time-to-time by Customer on notice
      following August 31, 2000 to add additional significant competitors of
      Customer) or (ii) one of the following entities: MCI Worldcom, Sprint,
      Qwest or Level 3, or an Affiliate of such entities.


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     13.4. Termination/Expiration Assistance; Transition Period.
           ----------------------------------------------------

           Upon expiration of this Agreement or any Schedule, or upon any
           termination or cancellation of this Agreement or any Schedule by
           either Party (whether or not for cause), Customer may decommission
           all Services corresponding to the Agreement or any such Schedule, as
           applicable, and Vendor shall (i) provide Customer, or at Customer's
           request Customer's designee, reasonable assistance and consultation
           to enable Customer (or Customer's designee) to ensure a smooth and
           timely transition of network control and management to Customer (as
           applicable), and to transition Customer's purchase of services
           similar to the Services then expiring or being terminated to another
           vendor, and (ii) continue to provide the Services then expiring or
           being terminated to Customer (at prices then in effect as of the date
           of such expiration, termination or cancellation) and otherwise
           perform all of its obligations under this Agreement (such obligations
           described in this Section 13.4 collectively "Transition Assistance")
           for a period (the "Transition Period") to be determined by Customer
           in its sole and absolute discretion; provided, however, that unless
           otherwise specified in a Schedule to the Agreement, the Transition
           Period shall not be longer than twelve (12) months after the
           effective date of such expiration, termination or cancellation. If
           the provision of such Transition Assistance follows a notice of
           termination by Vendor pursuant to Section 13.1(b) of this Master
           Agreement as a result of Customer's non-payment of undisputed amounts
           owed to Vendor, then Customer shall pay Vendor monthly in advance
           plus an equitable portion of the unpaid charges giving rise to
           termination that compensates Vendor for the provision of such
           Transition Assistance. As part of its obligation to provide
           Transition Assistance, Vendor shall include transferring all rights
           to Customer at no additional charge, for Customer and its designees'
           exclusive use, any telephone numbers used in providing the Services
           so that Customer or its designee may utilize such numbers in
           providing services (subject to the provisions of Schedule B regarding
           Vendor's obligations to obtain such telephone numbers for Customer).

14.  LIABILITY AND FORCE MAJEURE

     14.1. Liability Restrictions.
           ----------------------

           The liability restrictions and limitation provisions for each Service
           provided hereunder are set forth in the associated Schedule for such
           Service.

     14.2. Force Majeure.
           -------------

           (a)  No Party shall be liable for any default or delay in the
                performance of its obligations under this Agreement if and to
                the extent such default or delay is caused, directly or
                indirectly, by fire, flood, lightning, earthquake, elements of
                nature or acts of God, strikes, lock-outs or other labor
                disturbance, riots, civil disorders, rebellions or revolutions
                in any country, or any other cause beyond the reasonable control
                of such Party; provided, however, that the non-performing Party
                is without fault in causing such default or delay, and such
                default or delay could not have been prevented by reasonable
                precautions and cannot reasonably be circumvented by the non-
                performing Party through the use of alternate sources,
                workaround plans or other means (each a "Force Majeure Event").

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               The failure of a supplier or subcontractor of Vendor to perform
               under its agreement with Vendor shall not constitute a Force
               Majeure Event for Vendor except to the extent such supplier's or
               subcontractor's failure to perform is caused by a Force Majeure
               Event.

          (b)  In such event the non-performing Party shall be excused from
               further performance or observance of the obligation(s) so
               affected for as long as such circumstances prevail and such Party
               continues to use its commercially reasonable best efforts to
               recommence performance or observance whenever and to whatever
               extent possible without delay. In the event the Vendor is the
               non-performing Party, Customer shall be excused from paying for
               any Services affected by the Force Majeure Event. Any Party so
               delayed in its performance shall immediately notify the Party to
               whom performance is due by telephone (to be confirmed in writing
               within two (2) business days of the inception of such delay) and
               describe at a reasonable level of detail the circumstances
               causing such delay.

15.  INDEMNIFICATION

          Each Party agrees to indemnify, defend and hold harmless the other
          Party and its Affiliates and their respective officers, directors,
          employees, agents, successors, and assigns, from any and all losses,
          liabilities, damages and claims, and all related costs and expenses
          (including reasonable legal fees and disbursements and costs of
          investigation, litigation, settlement, judgment, interest and
          penalties) arising from, in connection with, or based on allegations
          of, any of the following:

          (a)  third party claims arising from the indemnifying Party's material
               breach of any obligation, representation or warranty under this
               Agreement;

          (b)  any claims of infringement of any patent, trademark, trade
               secret, copyright or other proprietary rights, alleged to have
               occurred based upon the provision by the indemnifying Party of
               materials, services or other resources to the indemnified Party;

          (c)  the death or bodily injury of any agent, employee, customer,
               business invitee, or business visitor of the indemnified Party or
               any other person caused by the tortious conduct of the
               indemnifying Party; or

          (d)  the damage, loss or destruction of any real or tangible personal
               property caused by the tortious conduct of the indemnifying
               Party.

16.  GENERAL

     16.1. Binding Nature and Assignment.
           -----------------------------

           This Agreement shall accrue to the benefit of and be binding upon the
           Parties hereto and any purchaser or any successor entity into which
           either Party has been merged or consolidated or to which either Party
           has sold or transferred all or substantially all of its assets.
           Neither Party may, or shall have the power to, assign this Agreement
           or delegate

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                        CONFIDENTIAL TREATMENT REQUIRED

          such Party's obligations hereunder without the prior written consent
          of the other, which consent shall not be unreasonably withheld or
          delayed, except that Customer may assign its rights and obligations
          under this Agreement without the approval of Vendor to an entity which
          acquires all or substantially all of the assets of Customer, to any
          Affiliate of Customer, or to a successor in a merger or acquisition of
          Customer. Notwithstanding anything to the contrary in this Section,
          but not affecting any of Customer's rights under Section 13.3,
          Customer hereby consents to the assignment of this Agreement to any
          entity created as a result of or arising out of the closing of the
          proposed merger of GTE Corporation and Bell Atlantic Corporation,
          including any transaction in which any assets of Vendor are
          transferred back to any Affiliate of the combined GTE/Bell Atlantic
          corporation.

    16.2. Continued Performance and Governing Law.

          (a)  Each Party agrees to continue performing its obligations under
               this Agreement while any dispute is being resolved except to the
               extent the issue in dispute precludes performance (dispute over
               payment shall not be deemed to preclude performance).

          (b)  This Agreement and performance under it shall be governed by and
               construed in accordance with the laws of the State of Delaware
               without regard to its choice of law principles.

    16.3. Entire Agreement.
          ----------------

          This Agreement, including any attached Schedules, sets forth the
          entire agreement of the Parties with respect to the transactions set
          forth herein.

    16.4. Notices.
          -------

          All notices, requests, demands, and determinations under this
          Agreement (other than routine operational communications or as
          otherwise specifically set forth herein (e.g., e-mail orders and
          Customer acceptance/rejection of Dedicated Dial-Up Access Ports or
          other Services)), shall be in writing and shall be deemed duly given
          (i) when delivered by hand, (ii) one (1) business day after being
          given to an express, overnight courier with a reliable system for
          tracking delivery, (iii) when sent by confirmed facsimile with a copy
          delivered by another means specified in this Section, or (iv) four (4)
          business days after the day of mailing, when mailed by United States
          mail, registered or certified mail, return receipt requested, postage
          prepaid, and addressed as follows:


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 -------------------------------------------------------------------------------
 To Customer:                                  To Vendor:
 -----------                                   ---------
 America Online, Inc.                          BBN Corporation
 12100 Sunrise Valley Drive                    9810 Patukent Woods Drive
 Reston, Virginia  20190                       Columbia, MD  21046
 Attn:  Geraldine MacDonald, Vice President    Attn:  Vice President and
        AOLnet Operations                             General Manager
 Fax:  (703) 265-5988                          Fax:  (410) 309-8315

 Copies to:                                    Copy to:
 ---------                                     -------
 America Online, Inc.                          GTE Internetworking
 22000 AOL Way                                 3 Van de Graaff Drive
 Dulles, Virginia  20166                       Burlington, MA 01803
 Attn: General Counsel                         Attn: General Counsel
 Fax:  (703) 265-1495                          Fax:  (781) 262-3408

 America Online, Inc.
 22000 AOL Way
 Dulles, Virginia  20166
 Attn:  President Of Business Affairs
 Fax:  (703) 265-1206
 -------------------------------------------------------------------------------

      A Party may from time to time change its address or designee for
      notification purposes by giving the other prior written notice of the new
      address or designee and the date upon which it will become effective.

16.5. Counterparts.
      ------------

      This Agreement may be executed in several counterparts, all of which taken
      together shall constitute one single agreement between the Parties hereto.

16.6. Relationship of Parties.
      -----------------------

      The Parties to this Agreement are independent contractors. Neither Party
      is an agent, representative, or partner of the other Party. Neither Party
      shall have any right, power or authority to enter into any agreement for
      or on behalf of, or incur any obligation or liability of, or to otherwise
      bind, the other Party. This Agreement shall not be interpreted or
      construed to create an association, agency, joint venture or partnership
      between the Parties or to impose any liability attributable to such a
      relationship upon either Party.

16.7. Severability.
      ------------

      In the event that any provision of this Agreement conflicts with the law
      under which this Agreement is to be construed or if any such provision is
      held invalid by a court with jurisdiction over the Parties, such provision
      shall be deemed to be restated to reflect as nearly as possible the
      original intentions of the Parties in accordance with applicable law. The
      remainder of this Agreement shall remain in full force and effect.

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     16.8.  Waiver of Default.
            -----------------

            No amendment, waiver or discharge hereof shall be valid unless in
            writing and signed by an authorized representative of the Party
            against which such amendment, waiver, or discharge is sought to be
            enforced. A delay or omission by either Party hereto to exercise any
            right or power under this Agreement shall not be construed to be a
            waiver thereof. A waiver by either of the Parties hereto of any of
            the covenants to be performed by the other or any breach thereof
            shall not be construed to be a waiver of any succeeding breach
            thereof or of any other covenant herein contained.

     16.9.  Cumulative Remedies.
            -------------------

            Except as otherwise expressly provided herein, all remedies provided
            for in this Agreement shall be cumulative and in addition to and not
            in lieu of any other remedies available to either Party at law, in
            equity or otherwise.

     16.10. Survival.
            --------

            Articles 10, 11, 14, 15, and 16 of this Master Agreement and,
            Section 1.2 of this Master Agreement, Schedule A, and Section 6.6 of
            Schedule B will survive the completion, expiration, termination or
            cancellation of the Agreement. In addition, any obligations which
            expressly or by their nature are to continue after termination,
            cancellation or expiration of the Agreement shall survive and remain
            in effect.

     16.11. Publicity.
            ---------

            (a)  Promotional Materials. Each Party shall submit to the other
                 ---------------------
                 Party, for its prior written approval, which will not be
                 unreasonably withheld or delayed, any marketing, advertising,
                 or other promotional materials to the extent such materials
                 reference the other Party or the other Party's trade names,
                 trademarks, and service marks (such materials the "Promotional
                 Materials").

            (b)  Press Releases. The Parties will prepare a mutually acceptable
                 --------------
                 joint press release for release following the Effective Date.
                 Each Party will submit to the other Party, for its prior
                 written approval, which will not be unreasonably withheld or
                 delayed, any press release or any other public statement (each,
                 a "Press Release") related to the transactions contemplated
                 hereunder. Without limiting the generality of the foregoing,
                 the inclusion in any such Press Release of any Confidential
                 Information or any information relating to prices or purchase
                 commitment terms of this Agreement shall be grounds for
                 withholding approval of such Press Release.

     16.12. Certain Regulatory Events.
            -------------------------

            In the event that Vendor is obligated under applicable law to
            provide any of the Services in accordance with tariffs filed with a
            governmental authority, then Vendor shall file the terms and
            conditions of this Agreement with such authority such that
            applicable law will require no change in the obligations of each
            Party under the Agreement. In the event that Vendor fails to file
            the terms and conditions of this Agreement in accordance with this
            Section, Customer may, at its option and in its sole discretion,
            exercise the

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            Agreement Termination Right for cause for those Schedules
            corresponding to the affected Services.

     16.13. Amendment.
            ---------

            This Agreement shall not be modified, amended or in any way altered
            except by an instrument in writing signed by both Parties.

     16.14. Incorporation by Reference.
            --------------------------

            Schedules A, B, C and D (including any Exhibits attached to such
            Schedules) are hereby incorporated by reference into this Master
            Agreement.












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     16.15. Construction.
            ------------

            The Parties agree that this Agreement was jointly drafted by the
            Parties and each Party further agrees that they shall not assert a
            claim that a particular provision should be construed against the
            other Party as the drafter of the provision. In addition, the
            headings and the table of contents in the Agreement are intended to
            be for reference purposes only and shall in no way be construed to
            modify or restrict, and shall not be considered in the construction
            or interpretation of, any of the terms or provisions of the
            Agreement.


IN WITNESS WHEREOF, Customer and Vendor have each caused this Agreement to be
signed and delivered by its duly authorized officer as of the Effective Date.


AMERICA ONLINE, INC.                   BBN CORPORATION

By: /s/ America Online, Inc.           By: /s/ Paul R. Gudonis
   --------------------------             -------------------------

Printed:                               Printed: Paul R. Gudonis
        ---------------------                  --------------------

Title:                                 Title: President
      ------------------------               ----------------------




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                                   SCHEDULE A

                                  Definitions

"Acceptance Criteria" means the criteria used to determine whether a Service is
ready for Final Acceptance. The Acceptance Criteria shall include the
requirements that the Service complies with all mutually agreed-upon testing
criteria as set forth in a Schedule to the Agreement and such other criteria as
may be developed and agreed upon by the Parties.

"Affiliate" of any entity means any other entity controlling, controlled by or
under common control with such entity.

"Agreement" has the meaning set forth in the preamble to the Master Agreement.

"Agreement Termination Right" means the right of a Party to terminate, without
cost or liability and as of the date specified in a written notice of
termination to Vendor, (a) the Schedule to which the breach giving rise to such
Agreement Termination Right relates, or (b) the entire Agreement. Any Schedule
not so terminated shall remain in full force and effect.

"Aggregate DSL Subscriber Lines" means the aggregate number of Subscriber Lines
providing xDSL broadband services that utilize the Broadband Backhaul Services
provided by Vendor or its Affiliates or the broadband backhaul services of any
other party. "Aggregate DSL Subscriber Lines" shall exclude Subscriber Lines of
any entity purchased, acquired, or merged with Customer or any Affiliate that,
as of the date of such purchase, acquisition or merger, are contractually
committed to another vendor of broadband backhaul services; provided that such
Subscriber Lines of such entity shall be excluded only for so long as the
duration (determined as of the date of such purchase, acquisition, or merger) of
such contractual commitment plus a mutually agreeable transition period.

"Aggregate Other Broadband Subscriber Lines" means the aggregate number of
Subscriber Lines providing broadband services that utilize the Broadband
Backhaul Services provided by Vendor or its Affiliates or the broadband backhaul
services of any other party. "Aggregate Other Broadband Subscriber Lines" shall
exclude (a) Subscriber Lines that transmit xDSL services, (b) Subscriber Lines
that utilize broadband services that are [*Material Omitted and Separately Filed
Under an Application for Confidential Treatment] service (i.e., a service where
the [*Material Omitted and Separately Filed Under an Application for
Confidential Treatment], and (c) Subscriber Lines of any entity purchased,
acquired, or merged with Customer or any Affiliate that, as of the date of such
purchase, acquisition or merger, are contractually committed to another vendor
of broadband backhaul services; provided that such Subscriber Lines of such
entity shall be excluded only for so long as the duration (determined as of the
date of such purchase, acquisition, or merger) of such contractual commitment
plus a mutually agreeable transition period.

"Aggregate Subscriber Lines" means the Aggregate DSL Subscriber Lines and
Aggregate Other Broadband Subscriber Lines, collectively.

"All New Ports MP Change Date" shall mean, for any New Dial-Up Market Price
Notice, the later of (a) the New Dial-Up Market Price Effective Date
corresponding to such New Dial-Up Market Price Notice, and (b) [*Material
Omitted and Separately Filed Under an Application for Confidential Treatment].

"ANI" has the meaning set forth in Section 11.1 of the Master Agreement.

"AOL Average" means, for a particular Service Level metric, the average
performance achieved with respect to such metric by other vendors of Customer
providing services similar to the Services corresponding to such Service Level
metric covering the same measurement period as the corresponding Service Level
measurement period.

"AOL Information Service" means a service (a) containing branding owned or
controlled by Customer or a Customer Affiliate, or using all or a portion of
Customer's or a Customer Affiliate's network or backend systems, or (b) in which
content, communications services and/or transactions are


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Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
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<PAGE>

provided to end-users through the use of any protocols, standards, platforms,
media or other methodology now or hereafter existing (including the Internet and
similar protocols, standards and platforms) from host server computers through
the use of client software resident on other computers or access devices.

"Applicable DUP Purchaser" has the meaning set forth in Section 8.3(b) of
Schedule B.

"Area Delivery Target" has the meaning set forth in Section 2.2(b) of Schedule
B.

"Base Port MP Change Date" shall mean, for any New Dial-Up Market Price Notice,
the later of (a) the New Dial-Up Market Price Effective Date corresponding to
such New Dial-Up Market Price Notice, and (b) [*Material Omitted and Separately
Filed Under an Application for Confidential Treatment].

"BPS", whether or not capitalized, shall mean bits per second.

"Broadband Backhaul" shall means the facility and associated managed services,
however provided in terms of technology, for receiving broadband traffic from
the public switched telephone network, a cable network, or a wireless network,
satellite network or other technologies, and delivering that traffic to a
Customer facility, where the end-user has initiated the connection. "Broadband
Backhaul" includes the provision of interconnection to an aggregation point and
the transport of bits from that aggregation point to a Customer facility.

"Broadband Backhaul Delivery Period" means, with respect to any New LATA, the
period commencing on the date Customer provides Vendor with the corresponding
New LATA Notice and ending on the later of (a) [*Material Omitted and Separately
Filed Under an Application for Confidential Treatment] days following such date,
and (b) if and only if Vendor has performed its obligations with respect to the
ATM intra-LATA interconnect (e.g., ordering of the circuit, management of the
associated third-party vendors), [*Material Omitted and Separately Filed Under
an Application for Confidential Treatment] days following the date on which the
local access provider is ready to activate the ATM intra-LATA interconnect in
such New LATA.

"Broadband Backhaul Market Vendor" has the meaning set forth in 7.2(a)(i)(2) of
Schedule C.

"Broadband Backhaul Purchase Commitments" means the DSL Purchase Commitment and
the Other Broadband Purchase Commitment, collectively.
"Broadband Backhaul Services" means (i) Broadband Backhaul ordered by Customer
pursuant to an Order to the extent accepted by Vendor pursuant to Schedule C and
managed network services associated therewith (including those services
described in Article 5 of Schedule C), and (ii) any other services described in
an Order to the extent accepted by Vendor pursuant to Schedule C, each of (i)
and (ii) as such services may change in accordance with the Agreement.

"Broadband Specifications" has the meaning set forth in Article 8 of Schedule C.

"Broadband Term" has the meaning set forth in Article 1 of Schedule C.

"Comparable Broadband Backhaul Services" means managed broadband backhaul
services that are comparable to Broadband Backhaul provided under Schedule C
(including comparable nationwide geographic distribution of Subscriber Lines
utilizing Broadband Backhaul and comparable terms and conditions).

"Comparable Dial-Up Services" means dedicated, managed dial-up access services
(not including usage-based dial-up access services) that are comparable to
Dial-Up Access provided under Schedule B (including comparable nationwide
geographic distribution of Dedicated Dial-Up Access Ports, and comparable terms
and conditions).

"Confidential Information" has the meaning set forth in Section 11.1 of the
Master Agreement.

"Covered Subscriber Line" has the meaning set forth in Section 9.1(b) of Exhibit
C-2 of Schedule C.

"Customer" has the meaning set forth in the preamble to the Master Agreement.

"Customer Data" means (i) all information or data provided to, or otherwise
learned or exposed to Vendor, Vendor's Affiliates or subcontractors by or on
behalf of Customer or end users of Customer's



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                       CONFIDENTIAL TREATMENT REQUESTED

services in conjunction with use of the Services (including such information
that is transmitted by or through the network(s) used to provide the Services),
and (ii) information derived from such information.

"Dedicated Dial-Up Access Port" is a Dial-Up Access Port that is (a) available
solely to the Customer and Special Affiliates, as applicable, and the end users
of Customer's and Special Affiliates' services, and (b) is not available to any
other party.

"Dial-Up Acceptance Test Period" has the meaning set forth in Section 2.7(a) of
Schedule B.

"Dial-Up Acceptance Testing" has the meaning set forth in Section 2.7(a) of
Schedule B.

"Dial-Up Access" is the facility and associated end-to-end, managed services,
however provided in terms of technology, for receiving analog or ISDN in-bound
calls from the public switched telephone network on demand and converting those
signals to digital form for transmission over digital networks, where the
end-user has initiated the call. "Dial-Up Access" includes the provision of
Dial-Up Access Ports.

"Dial-Up Access Port" is the capacity to offer Dial-Up Access to one (1)
incoming analog or ISDN in-bound call, plus signaling channels.

"Dial-Up Access Services" means (i) the "modems," managed, end-to-end network
services associated therewith, provided by Vendor to Customer under the Original
Agreement, (ii) Dial-Up Access ordered by Customer pursuant to an Order to the
extent accepted by Vendor pursuant to Schedule B and fully managed, end-to-end
network services associated therewith (including those services described in
Article 6 of Schedule B, and (iii) any other services described in an Order to
the extent accepted by Vendor pursuant to Schedule B, each of (i), (ii) and
(iii) as such services may change in accordance with the Agreement.

"Dial-Up Access Specifications" mean those Specifications described in Section
9.1 of Schedule B.

"Dial-Up Access Term" shall have the meaning set forth in Article 1 of Schedule
B.

"Dial-Up Market Vendor" has the meaning set forth in Section 8.3(a)(i)(2) of
Schedule B.

"Dial-Up Market Vendor Trigger" has the meaning set forth in Section 8.3(a)(i)
of Schedule B.

"Dial-Up Nonconformity" has the meaning set forth in Section 2.7(b)(i) of
Schedule B.

"Dial-Up Purchase Commitment" has the meaning set forth in Section 2.8(a) of
Schedule B.

"Disclosing Party" has the meaning set forth in Section 11.1 of the Master
Agreement.

"DSL Purchase Commitment" has the meaning set forth in Section 2.1 of Exhibit
C-1 of Schedule C.

"Effective Date" has the meaning set forth in the preamble to the Master
Agreement.

"Existing Calling Areas" means any rate center or calling area in which Vendor
(a) before the Effective Date provided, or agreed to provide, Dial-Up Access
Services to Customer (e.g., pursuant to the Original Agreement), or (b) during
the Term provides, or agrees to provide (e.g., pursuant to an Order), Dial-Up
Access Services to Customer.

"Existing Dedicated Dial-Up Access Port" has the meaning set forth in Section
8.1(b) of Schedule B.

"Existing LATA" means, at any given point in time, any LATA in which Vendor has
already provisioned Broadband Backhaul for xDSL for any customer.

"Final Acceptance" has the meaning set forth in Section 2.7(c) of Schedule B.

"Force Majeure Event" has the meaning set forth in Section 14.2 of the Master
Agreement.

"Include," "includes", and "including", whether or not capitalized, shall mean
"include but are not limited to", "includes but is not limited to", and
"including but not limited to", respectively.

"Incremental New Ports MP Change Date" shall mean, for any New Dial-Up Market
Price Notice, the later of (a) the New Dial-Up Market Price Effective Date
corresponding to such New Dial-Up Market Price Notice, and (b) [*Material
Omitted and Separately Filed Under an Application for Confidential Treatment]..


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                       CONFIDENTIAL TREATMENT REQUESTED

"L2TP" means Layer Two Tunneling Protocol.

"Leased Items" has the meaning set forth in Section 8.1(a)(ii) of Schedule B.

"Master Agreement" shall mean the Agreement excluding the Schedules to the
Agreement.

"Measurement Date" has the meaning set forth in Section 3.1 of Exhibit C-1 of
Schedule C.

"Monthly Aggregate Subscriber Line Charge" has the meaning set forth in Section
2.3(a) of Exhibit C-2 of Schedule C.

"Monthly DAP Charge" has the meaning set forth in Section 8.1(b) of Schedule B.

"Monthly EDAP Charge" has the meaning set forth in Section 8.1(a) of Schedule B.

"Monthly Pass-Through Expenses" has the meaning set forth in Section 7.1(b) of
Schedule C.

"Monthly Per Subscriber Line Charge" has the meaning set forth in Section 2.1 of
Exhibit C-2 of Schedule C.

"Monthly Subscriber Line Aggregate" has the meaning set forth in Section 2.3(a)
of Exhibit C-2 of Schedule C.

"Monthly Target" has the meaning set forth in Section 2.2 of Schedule B.

"New Broadband Backhaul Market Price" has the meaning set forth in Section
7.2(a)(i)(1) of Schedule C.

"New Broadband Backhaul Market Price Effective Date" means the date that is
ninety (90) calendar days after the New Broadband Backhaul Market Price Notice
Date corresponding to a New Broadband Backhaul Market Price Notice provided by
Customer.

"New Broadband Backhaul Market Price Notice" has the meaning set forth in
Section 7.2(a)(ii) of Schedule C.

"New Broadband Backhaul Market Price Notice Date" has the meaning set forth in
Section 7.2(a)(ii) of Schedule C.

"New Broadband Backhaul Market Price Response" has the meaning set forth in
7.2(a)(ii) of Schedule C.

"New Calling Area" means any rate center or calling area which is not an
Existing Calling Area.

"New Dial-Up Market Price" has the meaning set forth in Section 8.3(a) of
Schedule B.

"New Dial-Up Market Price Effective Date" means the date that is ninety (90)
calendar days after the New Dial-Up Market Price Notice Date corresponding to a
New Dial-Up Market Price Notice provided by Customer.

"New Dial-Up Market Price Notice" has the meaning set forth in Section
8.3(a)(ii) of Schedule B.

"New Dial-Up Market Price Notice Date" has the meaning set forth in Section
8.3(a)(ii) of Schedule B.

"New Dial-Up Market Price Response" has the meaning set forth in Section
8.3(a)(ii) of Schedule B.

"New LATA" means, at a given point in time, any LATA in which Vendor has not
already provisioned Broadband Backhaul for xDSL for any customer.

"New LATA Notice" has the meaning set forth in Section 1(c) of Schedule C.

"New Port" means any Dedicated Dial-Up Access Port that is not a Existing
Dial-Up Access Port.

"NOC" means a network operations center.

"Non-Terminable Breach" means a breach that does not, in and of itself, give
rise to Customer's right to exercise the Agreement Termination Right.

"Normalization Methodology" has the meaning set forth in Section 8.4(a) of
Schedule B.

"Order" means any valid order submitted by Customer pursuant to a Schedule to
this Agreement to the extent accepted or deemed accepted by Vendor pursuant to
such Schedule.

"Order Fulfillment Period" has the meaning set forth in Section 2.2 of Schedule
B.

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"Original Agreement" has the meaning given in Section 1.1(b) of the Master
Agreement.

"Other Broadband Purchase Commitment" has the meaning set forth in Section 2.2
of Exhibit C-1 to Schedule C.

"Other Services Purchase Commitment" has the meaning set forth in Schedule D.

"Other Vendors' Decom Share" means for any calendar quarter, the amount
calculated as (a) the total number of Dedicated Dial-Up Access Ports (including
usage-based Dial-Up Access Services adjusted using the Normalization
Methodology) provided to Customer other than by Vendor that are decommissioned
by Customer in such quarter, divided by (b) the total number of Dedicated
Dial-Up Access Ports (including usage-based Dial-Up Access Services adjusted
using the Normalization Methodology) provided to Customer other than by Vendor
that are installed and accepted at the beginning of such quarter.

"Out-of-Pocket Expenses" shall mean reasonable, verifiable and actual
out-of-pocket expenses and associated taxes, if any, incurred by a Party, but
excluding that Party's overhead costs (or allocations thereof), administrative
expenses or other mark-ups.

"Owned Items" has the meaning set forth in Section 8.1(a)(ii) of Schedule B.

"Party" and "Parties" has the meaning set forth in the preamble to the Master
Agreement.

"Peak Resale Window" has the meaning set forth in Section 4(b) of Schedule B.

"POP" means point of presence.

"Pre-Term Private Line Agreements" has the meaning set forth in Schedule D.

"Press Release" has the meaning set forth in Section 16.11(b) of the Master
Agreement.

"Private Line Services" has the meaning set forth in Schedule D.

"Promotional Materials" has the meaning set forth in Section 16.11(a) of the
Master Agreement.

"Purchase Commitments" means (i) the Dial-Up Purchase Commitment, (ii) the
Broadband Backhaul Purchase Commitments, and (iii) the Other Services Purchase
Commitment, collectively.

"Receiving Party" has the meaning set forth in Section 11.1 of the Master
Agreement.

[*Material Omitted and Separately Filed Under an Application for Confidential
Treatment] has the meaning set forth in Section 8(e) of Schedule C.

"Reportless Ports" has the meaning set forth in Section 8.5(a) of Schedule B.

"Resold Dial-Up Access" has the meaning set forth in Section 4(a) of Schedule B.

"Service Levels" means the quantitative and qualitative service levels
identified as such the Schedules to this Agreement.

"Services" means, collectively (i) Dial-Up Access Services, (ii) Broadband
Backhaul Services, (iii) Other Services, and (iv) any other services that the
Parties mutually agree in writing that are governed by the terms of this
Agreement.

"Significant Competitor" means, solely with respect to Section 13.3 of the
Master Agreement, any of the following entities or their Affiliates (which
entities may be modified from time-to-time by Customer on notice following
August 31, 2000): [*Material Omitted and Separately Filed Under an Application
for Confidential Treatment].

"Special Affiliate" means, with respect to Customer, (i) Customer's Affiliates,
(ii) any other entity in which Customer holds, either directly or indirectly, at
least an [*Material Omitted and Separately Filed Under an Application for
Confidential Treatment] equity interest, or (iii) any entity which operates or
distributes, or is authorized to operate or distribute, an AOL Information
Service.

"Specifications" means the specifications and other requirements for the
Services identified as such in a Schedule to the Agreement.

"Subscriber Line" means a dedicated connection, between an end user of services
of Customer or one of its Affiliates and an aggregation point, that is

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<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

activated and purchased by Customer or one or its Affiliates to provide services
to such end user.

"Term" has the meaning set forth in Article 2 of the Master Agreement.

"Transition Assistance" has the meaning set forth in Section 13.4 of the Master
Agreement.

"Transition Period" has the meaning set forth in Section 13.4 of the Master
Agreement.

"Valid Order Rejection Reason" has the meaning set forth in Section 2.3(a) of
Schedule B.

"Vendor" has the meaning set forth in the preamble to the Master Agreement.

"Vendor Broadband Subscriber Line" means a Subscriber Line used to transmit
broadband services that utilize the Broadband Backhaul Services provided by
Vendor or its Affiliates.

"Vendor Decom Share" means for any calendar quarter, the amount calculated as
(a) the total number of Dedicated Dial-Up Access Ports (including usage-based
Dial-Up Access Services adjusted using the Normalization Methodology) provided
by Vendor that are decommissioned by Customer in such quarter, divided by (b)
the total number of Dedicated Dial-Up Access Ports (including usage-based
Dial-Up Access Services adjusted using the Normalization Methodology) provided
by Vendor that are installed and accepted at the beginning of such quarter.

"Vendor ISP Affiliate" means any Affiliate of Vendor that offers online or
Internet connectivity services (e.g., an Internet service provider) to
consumers.

"Vendor Network" means any and all of the network or networks that support
Services ordered and accepted by Customer hereunder.

"Waiver" has the meaning set forth in Section 1.2(b) of the Master Agreement.

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                       CONFIDENTIAL TREATMENT REQUESTED

                                   SCHEDULE B

        Dial-Up Access Services, Service Levels, Pricing and Other Terms

1.   TERM

     The term of this Schedule B shall begin on the Effective Date and shall
     expire on December 31, 2006, unless terminated earlier in accordance with
     the Agreement, or extended by mutual written agreement (such period, as
     terminated earlier or so extended, the "Dial-Up Access Term").

2.   ORDERING

     2.1. New Markets.

          Vendor from time to time shall deliver to Customer a listing of any
          new rate centers or calling areas that are in addition to the Existing
          Calling Areas within which Vendor is willing to provide Dial-Up Access
          Services.

     2.2. Customer Submission of Orders.
          -----------------------------

          To order any Dial-Up Access Services, Customer shall submit to Vendor
          an order for such services covering the three-calendar month period
          beginning at least ninety (90) days following submission of the order
          (such three-month period the "Order Fulfillment Period"). Each order
          will set forth the following:

          (a)  the cumulative number of Dedicated Dial-Up Access Ports that
               Vendor must have installed and activated as of the end of each
               calendar month of an Order Fulfillment Period (for each calendar
               month, such number the "Monthly Target"), and

          (b)  the number of incremental Dedicated Dial-Up Access Ports for each
               calling area ordered by Customer during an Order Fulfillment
               Period (for each calling area, the "Area Delivery Target").

          Each order will be clearly marked as such, and will be delivered by
          Customer via electronic mail to such individuals designated in writing
          from time to time by Vendor. An e-mailed order will be valid only if
          it is submitted by the Vice President of AOLnet Operations, the
          Director for AOLnet Capacity Planning, or a designee of either.

     2.3. Vendor Acceptance or Rejection of Orders.
          ----------------------------------------

          (a)  Acceptance and Rejection Process.
               --------------------------------

               Vendor shall, within ten (10) business days after receipt of a
               valid order pursuant to Section 2.2 of this Schedule B, notify
               Customer of one of the following:

               (i)  its acceptance of such order; or

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                       CONFIDENTIAL TREATMENT REQUESTED

               (ii) its rejection of such order in whole or in part; provided
                    that Vendor may reject an order if and only to the extent
                    (1) the Monthly Target for a calendar month exceeds the
                    prior month's Monthly Target by more than [*Material Omitted
                    and Separately Filed Under an Application for Confidential
                    Treatment] Dedicated Dial-Up Access Ports, (2) such order
                    requests Dial-Up Access Services to be delivered in a New
                    Calling Area, (3) such order does not reflect the same
                    approximate weighted distribution of Dedicated Dial-Up
                    Access Ports across Existing Calling Areas, or (4) such
                    order requests the provision of Dedicated Dial-Up Access
                    Ports in excess of the Dial-Up Purchase Commitment (each of
                    (1), (2), (3) and (4) a "Valid Order Rejection Reason").

               If Vendor fails to provide Customer with such notice within such
               ten-day period, then such order shall be deemed accepted by
               Vendor. Vendor shall be obligated to deliver, in accordance with
               this Schedule B, the Dial-Up Access Services requested by
               Customer in an order to the extent such order is accepted or
               deemed accepted by Vendor. If Vendor rejects an order (or a
               portion thereof) for the reason described in Subsection (ii)(3)
               above, following notice of such objection by Vendor, the Parties
               will mutually agree on an equitable resolution consistent with
               the intent of this Section.

          (b)  Rejections by Vendor.
               --------------------

               To the extent that Vendor rejects an order (or portion thereof)
               for any reason other than a Valid Order Rejection Reason, the
               Dial-Up Purchase Commitment shall be reduced by the number of
               Dedicated Dial-Up Access Ports wrongfully rejected by Vendor.

          (c)  Additional Tasking.
               ------------------

               For any Order Fulfillment Period, in the event Vendor requests,
               Customer will provide Vendor with additional tasking of Dedicated
               Dial-Up Access Ports for Existing Calling Areas; provided,
               however, that such additional tasking shall not result in total
               tasking in excess of [*Material Omitted and Separately Filed
               Under an Application for Confidential Treatment] Dedicated
               Dial-Up Access Ports above the Monthly Target for the third month
               of the such Order Fulfillment Period. Customer will designate the
               Existing Calling Areas in which any of the Dedicated Dial-Up
               Access Ports corresponding to such additional tasking will be
               provided by Vendor. Any additional tasking shall not affect the
               Monthly Targets.

     2.4. Cancellation Without Cause and Rescheduling of Orders.
          -----------------------------------------------------

          (a)  Pre-Acceptance or Pre-Rejection Cancellation or Modification by
               ---------------------------------------------------------------
               Customer.
               --------

               Prior to acceptance or rejection of an order by Vendor, Customer
               may rescind or modify, in whole or in part in its sole
               discretion, such order.

          (b)  Post-Acceptance Cancellation or Modification by Customer.
               --------------------------------------------------------

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                       CONFIDENTIAL TREATMENT REQUESTED

               (i)  Customer may cancel or modify an Order in whole or in part
                    at any time in its discretion prior to the delivery of the
                    corresponding Dedicated Dial-Up Access Ports set forth in
                    such Order; provided, however, that except to the extent
                    otherwise agreed by Vendor, such cancellation or
                    modification shall not result in circumstances that would
                    constitute a Valid Order Rejection Reason. For any such
                    cancellation or modification, Customer will pay to Vendor
                    any incremental Out-of-Pocket Expenses actually incurred as
                    a result of such cancellation or modification and that could
                    not reasonably have been avoided by Vendor. Customer shall
                    have no liability to Vendor for an Order cancelled pursuant
                    to this Subsection (i) other than payment to Vendor of such
                    Out-of-Pocket Expenses.

               (ii) Customer's cancellation or modification of an Order pursuant
                    to this Subsection (b) shall not relieve Customer of its
                    obligations with respect to the Dial-Up Purchase Commitment.
                    In the event of significant changes to an Order by Customer,
                    Vendor may provide Customer with notice of impaired ability
                    to deliver, and the Parties shall mutually agree upon
                    appropriate changes to the Monthly Targets.

     2.5. Delivery.
          --------

          (a)  Notification of Delivery by Vendor.
               ----------------------------------

               Vendor shall only deliver Dedicated Dial-Up Access Ports that
               Vendor reasonably and in good faith believes will satisfy the
               applicable Acceptance Criteria. Upon delivery of any Dedicated
               Dial-Up Access Port (but no sooner than such delivery), Vendor
               shall provide to Customer notification of such delivery by e-mail
               to the Vice President of AOLnet Operations, the Director for
               AOLnet Capacity Planning, or a designee of either. For purposes
               of Subsection (e) of Section 2.5, delivery of any Dedicated
               Dial-Up Access Port shall be deemed made upon Customer's receipt
               of such e-mail from Vendor.

          (b)  Early Delivery By Vendor.
               ------------------------

               Vendor may deliver Dedicated Dial-Up Access Ports ordered by
               Customer before the commencement of the corresponding Order
               Fulfillment Period.

          (c)  Initial Testing Failure of Dedicated Dial-Up Access Ports.
               ---------------------------------------------------------

               Notwithstanding the deemed delivery date described in the last
               sentence of Subsection (a) of this Section, if any Dedicated
               Dial-Up Access Port provided in a month is not accepted by
               Customer prior to the 15th day of the next month, then such
               Dedicated Dial-Up Access Port will be deemed not to have been
               delivered during the first month.

          (d)  Delivery of Additional Tasking.
               ------------------------------

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                       CONFIDENTIAL TREATMENT REQUESTED

               In any month, Customer shall not be required to accept any
               Dedicated Dial-Up Access Ports in excess of [*Material Omitted
               and Separately Filed Under an Application for Confidential
               Treatment] Dedicated Dial-Up Access Ports above the Monthly
               Target for such month. With respect to any calling area, Customer
               shall not be required to accept any more Dedicated Dial-Up Access
               Ports in excess of the then-current Area Delivery Target for such
               calling area.

          (e)  Vendor Failures to Deliver.
               --------------------------

               (i)  Failure to Meet Monthly Target. If Vendor fails to deliver
                    ------------------------------
                    the Monthly Target in any month by more than [*Material
                    Omitted and Separately Filed Under an Application for
                    Confidential Treatment] Dedicated Dial-Up Access Ports, then
                    Customer may reduce the Dial-Up Purchase Commitment by the
                    number of Dedicated Dial-Up Access Ports over [*Material
                    Omitted and Separately Filed Under an Application for
                    Confidential Treatment] that Vendor fails to so deliver.

               (ii) Late Delivery.
                    -------------

                    Vendor shall use demonstrable good faith diligent efforts to
                    deliver Dedicated Dial-Up Access Ports in accordance with an
                    Order prior to the end of the corresponding Order
                    Fulfillment Period. Customer may reduce the Dial-Up Purchase
                    Commitment by the number of Dedicated Dial-Up Access Ports
                    included in an Order (A) for which Vendor has not delivered
                    a substantial portion of a Area Delivery Target by the end
                    of the corresponding Order Fulfillment Period and (B) with
                    respect to which Vendor has not used such efforts. In
                    addition, Customer may cancel, at no cost or liability to
                    Customer, the unfilled portion of the Order pertaining to
                    such Dedicated Dial-Up Access Ports. In the event of such
                    cancellation, Customer shall have no payment obligations to
                    Vendor with respect to the Dedicated Dial-Up Access Ports
                    corresponding to the cancelled portion or portions of the
                    Order. Upon Customer's request, Vendor shall provide
                    Customer with information and supporting documentation which
                    demonstrates Vendor's good faith diligent efforts to deliver
                    all Dedicated Dial-Up Access Ports set forth in an Order
                    prior to the end of the corresponding Order Fulfillment
                    Period (e.g., documents showing Vendor's ordering of
                    circuits from an access provider necessary to provision such
                    ordered Dedicated Dial-Up Access Ports as well as the
                    corresponding response from such access providers (e.g.,
                    firm order commitment)).

     2.6. Ordering Process Review.
          -----------------------

          The Parties acknowledge that the ordering process set forth in this
          Article 2 may require modification during the Dial-Up Access Term, and
          that in such event the Parties shall meet to discuss amending this
          Schedule to reflect any mutually agreed-upon modifications.

     2.7. Acceptance Testing and Final Acceptance.
          ---------------------------------------

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                       CONFIDENTIAL TREATMENT REQUESTED

          (a)  Acceptance Testing. Dedicated Dial-Up Access Ports ordered
               ------------------
               hereunder will require acceptance testing by Customer as
               described in this Section. Customer will have up to a [*Material
               Omitted and Separately Filed Under an Application for
               Confidential Treatment] business day period from the date such
               Dedicated Dial-Up Access Ports are delivered to Customer (the
               "Dial-Up Acceptance Test Period") in which to perform any
               reasonable testing as Customer in its sole discretion deems
               appropriate to determine whether such Dedicated Dial-Up Access
               Ports conform to their applicable Acceptance Criteria (the
               "Dial-Up Acceptance Testing"). If such Dedicated Dial-Up Access
               Ports meet their applicable Acceptance Criteria, Customer will
               notify Vendor (by electronic mail) that such Dedicated Dial-Up
               Access Ports have received Final Acceptance pursuant to
               Subsection (c) of this Section. Dedicated Dial-Up Access Ports
               activated and accepted by Customer prior to the Effective Date in
               accordance with the Original Agreement will be deemed accepted
               for purposes of this Agreement.

          (b)  Failure to Satisfy Acceptance Criteria.
               --------------------------------------

               (i)   If Dedicated Dial-Up Access Ports fail to conform to their
                     Acceptance Criteria (each such failure a "Dial-Up
                     Nonconformity"), Customer will notify Vendor within the
                     Acceptance Test Period (by electronic mail), specifying the
                     nature of the failure in reasonable detail. Vendor will
                     remove rejected Dedicated Dial-Up Access Ports from service
                     pending further troubleshooting and corrective action. At
                     no additional charge to Customer, Vendor shall use
                     commercially reasonable efforts to repair, replace or
                     otherwise correct the Dial-Up Nonconformity (and any other
                     problems of which it has knowledge) as soon as reasonably
                     practicable after receiving notice from Customer so that
                     the Dedicated Dial-Up Access Ports meet the applicable
                     Acceptance Criteria.

               (ii)  Upon completion of such efforts and Vendor's re-release of
                     Dedicated Dial-Up Access Ports to Customer, Customer shall
                     have an additional [*Material Omitted and Separately Filed
                     Under an Application for Confidential Treatment] business
                     day period to retest the re-delivered Dedicated Dial-Up
                     Access Ports to determine whether the previously reported
                     Dial-Up Nonconformity has been corrected and if such
                     Dedicated Dial-Up Access Ports otherwise then meet the
                     applicable Acceptance Criteria. This process will be
                     repeated as necessary until all Dial-Up Nonconformities are
                     corrected and such Dedicated Dial-Up Access Ports meet the
                     applicable Acceptance Criteria.

               (iii) Notwithstanding Subsection (ii) above, if after [*Material
                     Omitted and Separately Filed Under an Application for
                     Confidential Treatment] attempts for curing Dial-Up
                     Nonconformities, Vendor has not delivered such Dedicated
                     Dial-Up Access Ports conforming to the applicable
                     Acceptance Criteria, then Customer may:


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<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

                    (1)  allow Vendor to continue to try to correct any Dial-Up
                         Nonconformities;

                    (2)  if mutually agreed upon by the Parties, accept such
                         Dedicated Dial-Up Access Ports in their nonconforming
                         condition and reduce Vendor's charges for such
                         Dedicated Dial-Up Access Ports by a reasonable amount
                         as mutually determined by the Parties that shall
                         reflect the reduced value of such Dedicated Dial-Up
                         Access Ports; or

                    (3)  (A) cancel, in whole or in part, at no cost or
                         liability to Customer the portion of the corresponding
                         Order that does not conform as of a date specified in a
                         written notice of cancellation issued by Customer, and
                         (B) so long as the Dial-Up Nonconformities affect at
                         least[*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] ([*Material
                         Omitted and Separately Filed Under an Application for
                         Confidential Treatment]) of the Order, cancel, in whole
                         or in part, at no cost or liability to Customer the
                         unfilled portion of the corresponding Order as of a
                         date specified in a written notice of cancellation
                         issued by Customer. Customer shall have no payment
                         obligations to Vendor with respect to any cancelled
                         portion of an Order.

          (c)  Final Acceptance. Dedicated Dial-Up Access Ports ordered by
               ----------------
               Customer shall be deemed to be accepted (such acceptance the
               "Final Acceptance") only upon the earlier of: (i) receipt by
               Vendor of written notice by Customer certifying that such
               Dedicated Dial-Up Access Ports conform to the applicable
               Acceptance Criteria; or (ii) the expiration of the Dial-Up
               Acceptance Testing Period for such Dedicated Dial-Up Access Ports
               without notice of rejection by Customer. Notwithstanding anything
               to the contrary herein, Final Acceptance of Dedicated Dial-Up
               Access Ports shall only occur in accordance with the terms of
               this Agreement. Use of Dedicated Dial-Up Access Ports for
               business, profit, or any other purpose before Final Acceptance
               shall not constitute Final Acceptance by Customer.

     2.8. Dial-Up Purchase Commitments.
          ----------------------------

          (a)  Dial-Up Purchase Commitments.
               ----------------------------

               The Monthly Targets for Customer's purchase commitments are set
               forth in Exhibit B-1. The minimum commitments specified in
               Exhibit B-1 collectively, and as may be adjusted pursuant to the
               Agreement, shall be referred to as the "Dial-Up Purchase
               Commitment". All Dedicated Dial-Up Access Ports ordered by
               Customer pursuant to an Order shall contribute to Customer's
               satisfaction of the Dial-Up Purchase Commitment. Customer shall
               not be obligated to purchase any Dial-Up Access Services in
               excess of the Dial-Up


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                       CONFIDENTIAL TREATMENT REQUESTED

               Purchase Commitment (as such commitment may be adjusted pursuant
               to the Agreement).

          (b)  Application of Reductions in Purchase Commitments.
               -------------------------------------------------

               In the event that Customer is entitled to a reduction in the
               Dial-Up Purchase Commitment pursuant to the Agreement, each
               commitment described in Subsections (b), (c), (d), and (e) of
               Exhibit B-1 shall be reduced by the amount of such reduction. The
               Parties shall mutually agree upon a reasonable notification
               process with respect to reductions in the Dial-Up Purchase
               Commitment.

          (c)  Substitution of Purchase Commitments Under International
               --------------------------------------------------------
               Agreements.
               ----------

               If Vendor offers Customer or Special Affiliates dial-up access
               services for provision outside of the United States (excluding
               Japan) at market competitive prices and terms:

               (i)  Customer will use commercially reasonable efforts to
                    encourage such Special Affiliates to purchase in the
                    aggregate for all such Special Affiliates [*Material Omitted
                    and Separately Filed Under an Application for Confidential
                    Treatment] Dial-Up Access Ports from Vendor or Vendor's
                    Affiliates at such market competitive prices and terms; and

               (ii) If as of [*Material Omitted and Separately Filed Under an
                    Application for Confidential Treatment] such Special
                    Affiliates have not ordered, committed to order or purchase,
                    or actually purchased, in the aggregate for all such Special
                    Affiliates, [*Material Omitted and Separately Filed Under an
                    Application for Confidential Treatment] Dial-Up Access Ports
                    from Vendor or Vendor's Affiliates at market competitive
                    prices and terms with durations of at least [*Material
                    Omitted and Separately Filed Under an Application for
                    Confidential Treatment], then Customer shall purchase a
                    number of Dedicated Dial-Up Access Ports under this
                    Agreement equal to the difference between [*Material Omitted
                    and Separately Filed Under an Application for Confidential
                    Treatment] Dedicated Dial-Up Access Ports and the actual
                    number of dial-up access ports that such Special Affiliates
                    in the aggregate ordered, committed to order or purchase, or
                    actually ordered from Vendor or Vendor's Affiliates as of
                    such date (as determined utilizing the Normalization
                    Methodology if applicable). Notwithstanding the foregoing,
                    if (1) a Special Affiliate is offered services by a third
                    party similar to the Dial-Up Access Services ordered or
                    purchased pursuant to this Agreement at prices and terms
                    more competitive than those offered by Vendor or Vendor's
                    Affiliates to such Special Affiliate in a country in which
                    Vendor either has operations or has indicated an intent in
                    which to operate, (2) such Special Affiliate, in its sole
                    discretion, requests Vendor to provide Dial-Up Access
                    Services

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<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

                    at prices and terms at least as favorable to Special
                    Affiliate as such prices and terms offered by such third
                    party, and (c) Vendor or Vendor's Affiliates declines to
                    provide such services at such prices and terms, then
                    Customer's obligation under this Subsection (c) shall be
                    reduced by the aggregate amount of Dial-Up Access Ports
                    purchased by such Special Affiliate from such third party.

3.   Relocation of dial-Up access services

     Customer shall have the right to direct at any time a change in the
     location in which Dial-Up Access Services are provided within Existing
     Calling Areas (including a reallocation of Dedicated Dial-Up Access Ports
     among locations). In the event that Customer provides Vendor with notice of
     such direction, Vendor shall comply with such direction within a reasonable
     time; provided, however, that (a) any additional reasonable costs incurred
     by Vendor, including any reasonable service termination or service
     activation costs, will be reimbursed by Customer on an Out-of-Pocket
     Expenses basis, (b) with respect to Dial-Up Access Services, Customer shall
     not direct relocation of more than [*Material Omitted and Separately Filed
     Under an Application for Confidential Treatment] Dedicated Dial-Up Access
     Ports in any given calendar month; and (c) such relocation shall result in
     the same approximate weighted distribution of Dedicated Dial-Up Access
     Ports across Existing Calling Areas.

4.   RESALE OF DIAL-UP ACCESS SERVICES

          (a)  Unless otherwise agreed by Customer in writing:

               (i)  Each Dedicated Dial-Up Access Port shall be exclusively
                    available to Customer and its Special Affiliates to whom
                    Vendor is providing Dedicated Dial-Up Services; and

               (ii) Vendor shall not resell or offer to resell any Dedicated
                    Dial-Up Access Port ordered and accepted by Customer;

               provided however, that Vendor may continue to provide access, at
               current levels or levels that are lesser than current levels and
               consistent with Vendor's obligations under section 10 of the
               Original Agreement, as amended, with respect to (A) until (but no
               later than) January 31, 2000, Dedicated Dial-Up Access Ports
               (excluding the approximately [*Material Omitted and Separately
               Filed Under an Application for Confidential Treatment] rotaries)
               to those Vendor customers that are using such Dedicated Dial-Up
               Access Ports as of the Effective Date, and (B) until (but no
               later than) February 29, 2000, the approximately [*Material
               Omitted and Separately Filed Under an Application for
               Confidential Treatment] rotaries to those Vendor customers that
               are using the same as of the Effective Date (such access "Resold
               Dial-Up Access"), subject to Vendor's payment to Customer of
               access royalties calculated pursuant to this Article 4. At no
               time during the Peak Resale Window (as defined below) may access
               that Vendor is permitted to provide to customers pursuant to this
               Subsection (a) exceed [*Material Omitted and Separately Filed
               Under an Application for Confidential Treatment] ([*Material

--------------------------------------------------------------------------------
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<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

               Omitted and Separately Filed Under an Application for
               Confidential Treatment] %) of the Dedicated Dial-Up Access Port
               capacity that Vendor is required to provide pursuant to this
               Schedule B.

          (b)  Access royalties payable by Vendor pursuant to Subsection (a) of
               this Article 4 for Resold Dial-Up Access authorized pursuant to
               such Subsection (a) and occurring before January 1, 2000 shall be
               calculated as follows:

               (i)   For each of the first [*Material Omitted and Separately
                     Filed Under an Application for Confidential Treatment]
                     aggregate hours of Resold Dial-Up Access in a calendar
                     month, the applicable access royalty shall be [*Material
                     Omitted and Separately Filed Under an Application for
                     Confidential Treatment].

               (ii)  For each of the first [*Material Omitted and Separately
                     Filed Under an Application for Confidential Treatment]
                     hours of Resold Dial-Up Access in a calendar month in
                     excess of the [*Material Omitted and Separately Filed Under
                     an Application for Confidential Treatment] hours described
                     in Subsection (i) of this Subsection (b), the applicable
                     access royalty shall be [*Material Omitted and Separately
                     Filed Under an Application for Confidential Treatment]
                     cents ($.[*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment]) per hour per
                     month.

               (iii) For each hour of Resold Dial-Up Access in a calendar month
                     in excess of the [*Material Omitted and Separately Filed
                     Under an Application for Confidential Treatment] aggregate
                     hours described in Subsections (i) and (ii) of this
                     Subsection (b), the applicable access royalty shall be
                     [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] cents ($.[*Material
                     Omitted and Separately Filed Under an Application for
                     Confidential Treatment]) per hour per month.

               The number of hours of Resold Dial-Up Access during the hours
               between 8:00 p.m. local time and midnight local time daily (such
               daily period the "Peak Resale Window") for Resold Dial-Up Access
               occurring before January 1, 2000 shall not exceed [*Material
               Omitted and Separately Filed Under an Application for
               Confidential Treatment] ([*Material Omitted and Separately Filed
               Under an Application for Confidential Treatment]%) of the
               aggregate number of hours of Resold Dial-Up Access, measured
               quarterly, except that the number of hours of Resold Dial-Up
               Access occurring before January 1, 2000 during the Peak Resale
               Window shall not exceed [*Material Omitted and Separately Filed
               Under an Application for Confidential Treatment] percent
               ([*Material Omitted and Separately Filed Under an Application for
               Confidential Treatment]%) for Dedicated Dial-Up Access Ports
               beyond [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment]. In the event that Vendor
               does not comply with such restriction, Vendor will pay Customer,
               in addition to the access royalties

--------------------------------------------------------------------------------
Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Schedule B                    Schedule B - Page 9
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

               described above, an additional access royalty of [*Material
               Omitted and Separately Filed Under an Application for
               Confidential Treatment] cents ($.[*Material Omitted and
               Separately Filed Under an Application for Confidential
               Treatment]) [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment] per hour for each hour of
               Resold Dial-Up Access sold in violation of such restriction.

          (c)  Access royalties payable by Vendor pursuant to Subsection (a) of
               this Article 4 for Resold Dial-Up Access authorized pursuant to
               such Subsection (a) and occurring on or after January 1, 2000 but
               before or during February 29, 2000, for each hour of Resold
               Dial-Up Access shall be [*Material Omitted and Separately Filed
               Under an Application for Confidential Treatment] cents
               ($.[*Material Omitted and Separately Filed Under an Application
               for Confidential Treatment]) per hour per month. The number of
               hours of Resold Dial-Up Access during the Peak Resale Window for
               Resold Dial-Up Access occurring on or after January 1, 2000 but
               before February 29, 2000 shall not exceed [*Material Omitted and
               Separately Filed Under an Application for Confidential Treatment]
               percent ([*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment]%) of the aggregate number
               of hours of Resold Dial-Up Access during such period, measured
               quarterly. In the event that Vendor does not comply with such
               restriction, Vendor will pay Customer, in addition to the access
               royalties described in this Subsection (c), an additional access
               royalty of [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment] cents ($[*Material
               Omitted and Separately Filed Under an Application for
               Confidential Treatment]) [*Material Omitted and Separately Filed
               Under an Application for Confidential Treatment] per hour for
               each hour of Resold Dial-Up Access sold in violation of such
               restriction.

          (d)  For any Resold Dial-Up Access occurring in violation of
               Subsection (a) of this Article 4 with respect to the Vendor
               customers referenced in the proviso of such Subsection (a),
               Vendor shall pay Customer, as its sole and exclusive remedy, an
               amount equal to [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment] dollars ($[*Material
               Omitted and Separately Filed Under an Application for
               Confidential Treatment]) [*Material Omitted and Separately Filed
               Under an Application for Confidential Treatment] per hour for
               each hour of Resold Dial-Up Access in violation of Subsection (a)
               of this Article 4, and any such violation shall not be deemed to
               be a breach triggering a termination right under Section 13.1(a)
               of the Master Agreement. For any other resale of Dedicated
               Dial-Up Access Ports in violation of Subsection (a) of this
               Article 4, Vendor shall pay to Customer the [*Material Omitted
               and Separately Filed Under an Application for Confidential
               Treatment] per hour charge described in this Subsection, and such
               violation shall also be deemed a material breach entitling
               Customer to terminate the Agreement in accordance with Section
               13.1(a) of the Master Agreement. Vendor shall promptly report to
               Customer any Resold Dial-Up Access occurring in violation of
               Subsection (a) of this Article 4.

--------------------------------------------------------------------------------
Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Schedule B                    Schedule B - Page 10
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

          (e)  Promptly following the end of each of first three calendar months
               after the Effective Date (i.e., December, 1999, and January,
               February 2000), Vendor will provide Customer with a report
               summarizing the aggregate number of hours of Resold Dial-Up
               Access or other Services for such month and the corresponding
               access royalties, if any, payable by Vendor pursuant to this
               Article 4.

5.   TRANSITION PERIOD and limitation of liability

     5.1. Transition Period.
          -----------------

          The Transition Period applicable to Dial-Up Access Services shall be
          equal to three months for each [*Material Omitted and Separately Filed
          Under an Application for Confidential Treatment] Dial-Up Access Ports
          existing as of the effective date of expiration, termination or
          cancellation (but in no event shorter than 12 months).

     5.2. Liability Restrictions.

          (a)  Subject to Subsection (e) of this Section, the liability of
               Vendor to Customer for all damages arising out of or related to
               the Services provided under this Schedule will be limited to, and
               will not exceed, in the aggregate during any calendar year,
               [*Material Omitted and Separately Filed Under an Application for
               Confidential Treatment] percent ([*Material Omitted and
               Separately Filed Under an Application for Confidential
               Treatment]%) of the aggregate amounts paid to Vendor by Customer
               (excluding Out-of-Pocket Expenses) under this Schedule and the
               Original Agreement during the twelve (12) month period preceding
               the date of the event giving rise to such damages. Subject to
               Subsections (c) and (e) of this Section, the liability of Vendor
               to Customer for damages arising out of or related to Services
               provided under this Schedule caused by the acts or omissions of
               third parties beyond the reasonable control of Vendor will be
               further limited and will not exceed, in the aggregate during any
               calendar year, [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment] Dollars ($[*Material
               Omitted and Separately Filed Under an Application for
               Confidential Treatment]).

          (b)  By way of example and without limitation, in the event that four
               events occur in calendar year 2000, as described below, for which
               Vendor would have liability to Customer under Subsection (a) of
               this Section, then Vendor's liability to Customer for each such
               event would be as follows:

               (i)  An event in March 2000 that is not caused by the acts or
                    omissions of third parties causing Customer damages of $17
                    million, with the preceding twelve month amounts paid of
                    $350 million, the liability of Vendor to Customer for such
                    event would be $[*Material Omitted and Separately Filed
                    Under an Application for Confidential Treatment]; and

               (ii) An event in June 2000 that is caused by the acts or
                    omissions of third parties beyond the reasonable control of
                    Vendor causing Customer

--------------------------------------------------------------------------------
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<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

                     damages of $12 million, with the preceding twelve months
                     amounts paid of $375 million, the liability of Vendor to
                     Customer for such event would be $[*Material Omitted and
                     Separately Filed Under an Application for Confidential
                     Treatment] subject to Vendor's obligations set forth in
                     Subsection (c) of this Section; and

               (iii) An event in October 2000 that is not caused by the acts or
                     omissions of third parties causing Customer damages of $15
                     million, with preceding twelve month amounts paid of $400
                     million, the liability of Vendor to Customer for such event
                     would be $[*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment]; and

               (iv)  An event in December 2000 that is caused by the acts or
                     omissions of third parties beyond the reasonable control of
                     Vendor causing Customer damages of $3 million, with the
                     preceding twelve months amounts paid of $425 million, the
                     liability of Vendor to Customer for such event would be $
                     [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] subject to Vendor's
                     obligations set forth in Subsection (c) of this Section.

          (c)  In the event of any liability of Vendor to Customer for damages
               arising out of or related to Services provided under this
               Schedule caused by the acts or omissions of third parties beyond
               the reasonable control of Vendor, then the Parties agree as
               follows:

               (i)   Vendor agrees to vigorously pursue the recovery of damages
                     against the third party causing the damage, including
                     through negotiations, dispute resolution, or both, to
                     maximize the damages recoverable against such third party;

               (ii)  Vendor agrees to pass through to Customer any amounts that
                     Vendor actually recovers from such third party relating to
                     damages incurred in connection with Services provided to
                     Customer under this Schedule; and

               (iii) Customer agrees that in the event that Vendor has paid any
                     amounts to Customer pursuant to Subsection (a) of this
                     Section prior to the recovery of damages from a third
                     party, that Vendor may reduce the amount of recovery
                     received from such third party by the amount previously
                     paid to Customer in respect of such event causing the
                     damages.

               (iv)  Amounts recovered by Vendor from third parties shall first
                     be passed on to Customer until Customer's full damages are
                     satisfied.

          (d)  IN NO EVENT, WHETHER IN CONTRACT OR IN TORT (INCLUDING BREACH OF
               WARRANTY, NEGLIGENCE AND STRICT LIABILITY IN TORT), SHALL A PARTY
               BE LIABLE TO THE OTHER PARTY FOR INDIRECT OR CONSEQUENTIAL,
               EXEMPLARY, PUNITIVE OR SPECIAL


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<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

               DAMAGES EVEN IF SUCH PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
               SUCH DAMAGES IN ADVANCE.

          (e)  The limitations set forth in Subsection (a) of this Section shall
               not apply with respect to (i) intentional breach by Vendor; (ii)
               damages occasioned by an intentional tort or the gross negligence
               of Vendor; (iii) damages occasioned by Vendor's breach of its
               obligations described in Article 11 (Confidentiality) of the
               Master Agreement, or (iv) claims subject to indemnification
               pursuant to this Agreement (such amounts paid by the indemnitee
               to third parties shall be deemed to be direct damages) other than
               claims subject to the indemnity set forth in Section 15(a) of the
               Master Agreement.

          (f)  Each Party shall have a duty to reasonably mitigate (i.e.,
               minimize) damages for which the other Party is responsible.

6.   DESCRIPTION OF DIAL-UP ACCESS SERVICES

     Dial-Up Access Services shall include the provision of Dial-Up Access and
     all associated fully managed, end-to-end network service functions
     including the following:

     6.1. General Requirements.
          --------------------

          (a)  Vendor shall provide, for each individual Existing Calling Area,
               a unique set of source IP addresses such that member demographics
               can be identified through such source IP addresses. Customer
               shall be provided the source IP addresses prior to use by Vendor
               to provide the Services.

          (b)  Vendor shall acquire and manage IP addresses for all protocols
               utilized by Customer during the Term.

          (c)  Vendor shall provide domain name services, including the
               following:

               (i)   provision of domain name service for Customer;

               (ii)  resolution of domain name service queries to Customer
                     destinations;

               (iii) support of domain name service for Customer service access
                     to the Customer domain and any zones resident on Customer
                     name servers; and

               (iv)  maintenance of domain name service servers.

          (d)  In the event that Customer requests a change to its access
               method(s), hub architecture, or network bandwidth from that which
               is described in this Schedule B (other than a request for
               increased throughput priced pursuant to Section 8.1(c) of this
               Schedule B), Vendor will provide Customer with Vendor's proposed
               increase, if any, to the prices set forth in this Schedule B. To
               the extent that Customer accepts such proposal, Vendor shall
               provide the Dial-Up

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<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

               Access Services in accordance with the requested change and
               Vendor's proposal to the extent accepted by Customer.

          (e)  Vendor will utilize GNI for delivery of data traffic to
               Customer's data centers; provided that, in order to provide last
               mile diversity, at Customer's request, for up to [*Material
               Omitted and Separately Filed Under an Application for
               Confidential Treatment] of the GNI last mile capacity to
               Customer's facilities, Customer and Vendor agree to exchange
               local facilities, at no cost to either Party for equivalent
               bandwidth exchanged. The Parties agree to establish a mutually
               acceptable bandwidth exchanging and circuit management process,
               including co-location space, facility access, and helping hands
               where both Parties have local facilities in each geography.

     6.2. Network Engineering.
          -------------------

          Vendor agrees to provide network engineering to address operational
          and long-term planning issues.

     6.3. Operations.
          ----------

          Vendor will provision, staff, and operate a NOC (currently in
          Columbia, Maryland) with dedicated support for Customer and a backup
          NOC at a separate location (such backup NOCs currently located in
          Chantilly, Virginia). The scope of this task will include the
          following Vendor support services for the network:

          (a)  Operation of the NOC and co-located systems with trained and
               qualified personnel on a continuous, 24 hours per day, 7 days per
               week basis;

          (b)  Operation of all NOC equipment, monitoring, and fault isolation
               functions;

          (c)  Coordination of the dispatch of maintenance representatives for
               corrective maintenance activities and recording information in a
               Problem Report ("PR"). Vendor's responsibilities shall include:

               (i)   Initiation of a [*Material Omitted and Separately Filed
                     Under an Application for Confidential Treatment] request,
                     plus recording the time that the call is received by the
                     Vendor maintenance representative;

               (ii)  Upon arrival of the maintenance representative at the site,
                     confirmation by the [*Material Omitted and Separately Filed
                     Under an Application for Confidential Treatment] and
                     recording the [*Material Omitted and Separately Filed Under
                     an Application for Confidential Treatment] with the
                     representative;

               (iii) Upon notification to the NOC by the on-site maintenance
                     representative of [*Material Omitted and Separately Filed
                     Under an Application for Confidential Treatment] access to
                     the [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] shall provide
                     Customer with relevant information; and

--------------------------------------------------------------------------------
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<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

               (iv)  Upon restoration of service by the maintenance
                     representative, the NOC shall confirm, with assistance from
                     the maintenance representative, operation of the [*Material
                     Omitted and Separately Filed Under an Application for
                     Confidential Treatment] when [*Material Omitted and
                     Separately Filed Under an Application for Confidential
                     Treatment] are [*Material Omitted and Separately Filed
                     Under an Application for Confidential Treatment] and the
                     reason for the [*Material Omitted and Separately Filed
                     Under an Application for Confidential Treatment];

          (d)  Initiation of [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment] maintenance of a
               [*Material Omitted and Separately Filed Under an Application for
               Confidential Treatment] coordination of [*Material Omitted and
               Separately Filed Under an Application for Confidential Treatment]
               with support personnel and tracking of problems until resolution
               using a commercially available [*Material Omitted and Separately
               Filed Under an Application for Confidential Treatment] reporting
               software system;

          (e)  Utilization of [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment] resident in the NOC for:

               (i)   Daily testing of [*Material Omitted and Separately Filed
                     Under an Application for Confidential Treatment] and
                     [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment];

               (ii)  Measurements of the usage of each [*Material Omitted and
                     Separately Filed Under an Application for Confidential
                     Treatment] at the frequency or at the times requested by
                     Customer;

               (iii) Monitoring and recording the [*Material Omitted and
                     Separately Filed Under an Application for Confidential
                     Treatment] and [*Material Omitted and Separately Filed
                     Under an Application for Confidential Treatment] and
                     [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment];and

               (iv)  Accounting for the disposition of each [*Material Omitted
                     and Separately Filed Under an Application for Confidential
                     Treatment] (e.g., how many [*Material Omitted and
                     Separately Filed Under an Application for Confidential
                     Treatment] how many [*Material Omitted and Separately Filed
                     Under an Application for Confidential Treatment] how many
                     [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] how many [*Material
                     Omitted and Separately Filed Under an Application for
                     Confidential Treatment] subject to Section 8.5(a) of this
                     Schedule B;

          (f)  Providing on-site analyst support, at the NOC utilized to provide
               Dial-Up Access Services, [*Material Omitted and Separately Filed
               Under an Application for Confidential Treatment]. A dedicated
               access number shall be maintained for Customer's exclusive use,
               which shall always be [*Material Omitted and

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                       CONFIDENTIAL TREATMENT REQUESTED

               Separately Filed Under an Application for Confidential
               Treatment]. Analyst support shall include the following:

               (i)   Supporting short-term and long-term problem identification,
                     analysis, and resolution;

               (ii)  Ensuring that proper steps are taken to resolve the
                     problem;

               (iii) Identifying and tracking all software, baseline and
                     patches, deployed in the Vendor Network and NOC platforms;

               (iv)  Supporting the deployment of new software to the Vendor
                     Network, Customer's networks and NOC equipment as
                     coordinated with Customer;

               (v)   Providing support to network provisioning requirements; and

               (vi)  Maintaining a technical library for the NOC.

          (g)  Performing on-call analyst support of the Vendor Network on a
               continuous 24 hour per day, 7 days per week basis. On-call
               analyst personnel respond to urgent requests from the NOC in
               conjunction with the on-site Vendor personnel. Procedures for the
               conduct of network testing are in accordance with those developed
               in conjunction with Customer representatives;

          (h)  Providing operational support to Customer in the area of network
               testing in association with provisioning actions. Such testing
               shall be conducted from the NOC in conjunction with the on-site
               Vendor installation team personnel;

          (i)  Maintaining and providing updates and changes to NOC maps;

          (j)  Maintaining an authorized outage listing for NOC controller use;

          (k)  Acting as Customer's agent in network security matters on a
               day-to-day basis as directed by Customer in accordance with
               commercially reasonable practices, and making recommendations for
               improvements;

          (l)  Using commercial teleconferencing facilities in the resolution of
               network problems, escalation of problems, and planning
               activities;

          (m)  Providing electronic mail service support for the NOC [*Material
               Omitted and Separately Filed Under an Application for
               Confidential Treatment];

          (n)  Providing a facsimile service resident in the NOC equipment;

          (o)  Subject to Section 8.5(a) of this Schedule B, delivering the
               following reports to Customer-designated representatives:

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                       CONFIDENTIAL TREATMENT REQUESTED

               (i)   [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] reports;

               (ii)  [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] summaries of the
                     [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment];

               (iii) [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] report;

               (iv)  [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] statistics;

               (v)   [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] statistics; and

               (vi)  [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] data as required to
                     [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] problems;

               Customer may request additional reports that assist in improving
               the quality of the Vendor Network and Customer's networks. Vendor
               will provide these additional reports, or the raw data, subject
               to technical reasonableness.

     6.4. Network Support Organization.
          ----------------------------

          Vendor shall structure the provision of Services in a manner that will
          enable Vendor to rapidly build out its networks and deliver quality
          Services.

          (a)  Program Management: Vendor's program management group shall
               ------------------
               responsible for the management of the Services as a whole. The
               program management team shall be led by a program executive who
               has direct and immediate access to the senior management of
               Vendor and a program manager who reports to such program
               executive. The program management team shall be (i) the primary
               point of contact between Vendor and Customer and shall coordinate
               the activity of all functional groups within Vendor and (ii)
               responsible for project and financial management of the Services.

          (b)  Engineering: Vendor shall maintain an network engineering group
               -----------
               that shall handle the technical aspects of the Services,
               resolution of problems escalated by the NOC, planning for future
               network expansion, and improvement of performance and process.
               Such engineering group shall interact directly with Customer and
               the NOC.

          (c)  Deployment: Vendor shall maintain a deployment team consisting of
               ----------
               field engineers and technicians, as well as others who have
               experience dealing directly with telcos, preparing sites, and
               installing equipment. Part of this team

--------------------------------------------------------------------------------
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                       CONFIDENTIAL TREATMENT REQUESTED

               will be based at Vendor's facilities to coordinate activities and
               provide support for installers.

          (d)  Operations: Vendor's NOC shall handle the operation and
               ----------
               maintenance of the Vendor Network. The NOC will be connected to
               Customer's central facilities, including a direct telephone link
               to the Customer operations center. The NOC's monitoring
               capability shall be set up to detect and correct most network
               problems before they are visible to Customer or its customers.

     6.5. Other Services.
          --------------

          (a)  The NOC shall direct maintenance activities based on input from
               the monitoring systems and Customer. Vendor shall handle a large
               majority of repair tasks over the telephone with technicians at
               the Dial-Up Access Port equipment locations by storing Dial-Up
               Access subsystems at these locations, establishing working
               agreements with the service providers at these locations, and by
               providing written procedures. When it is necessary to send
               technicians to deal with problems, Vendor shall use its existing
               infrastructure of satellite offices and field engineers.

          (b)  Vendor agrees not to restrict Customer's dial-up traffic to and
               from Customer unless requested to do so by Customer or required
               to do so by court order or applicable law.

          (c)  The Parties shall use commercially reasonable efforts to
               [*Material Omitted and Separately Filed Under an Application for
               Confidential Treatment] information sent to each other and to
               [*Material Omitted and Separately Filed Under an Application for
               Confidential Treatment] and withdrawal of [*Material Omitted and
               Separately Filed Under an Application for Confidential Treatment]
               equipment.

          (d)  Vendor shall announce Customer [*Material Omitted and Separately
               Filed Under an Application for Confidential Treatment]
               information at [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment] as required by Customer.

          (e)  Vendor shall reasonably coordinate with Customer regarding any
               maintenance activity.

     6.6. Telephone Numbers Used to Provide Dial-Up Access Services.
          ---------------------------------------------------------

          (a)  Upon (i) the request of Customer from time to time, (ii)
               expiration of the Agreement or Schedule B of the Agreement, or
               (iii) any termination of the Agreement or Schedule B of the
               Agreement, Vendor shall provide Customer with a complete listing
               of telephone numbers used to provide Dial-Up Access Services.
               Ownership of such telephone number shall be governed by the
               Master Agreement. Vendor shall not provide such telephone numbers
               for use by Vendor (except to the extent necessary for Vendor to
               provide the Dial-Up

--------------------------------------------------------------------------------
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<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

               Access Services) or any third party (other than third parties
               designated by Customer from time to time) without prior written
               permission from Customer.

          (b)  For each telephone number to a Dial-Up Access Port equipment
               location, and upon the decommissioning of corresponding Dial-Up
               Access Services and upon the expiration or termination of this
               Schedule B or the Agreement:

               (i)  If such telephone number is provided by Vendor or an
                    Affiliate of Vendor, Vendor shall, to the extent legally
                    permitted to do so, obtain the rights necessary for Customer
                    or a designee of Customer to utilize such telephone number
                    to provide services upon any expiration or termination of
                    this Schedule B; and

               (ii) If such telephone number is provided by an entity other than
                    by Vendor or an Affiliate of Vendor, then Vendor shall use
                    commercially reasonable efforts to obtain the rights
                    necessary for Customer or a designee of Customer to utilize
                    such telephone number to provide services upon any
                    expiration or termination of this Schedule B.

          (c)  Vendor shall provide Customer with no less than thirty (30) days
               advance written notice before it changes any telephone number to
               a Dial-Up Access Port equipment location. Vendor shall not
               utilize any new telephone number to provide Dial-Up Access
               Services until Customer has accepted such telephone number in the
               manner described in Section 2.7 of this Schedule B. In the event
               of any such change, (i) Vendor shall provide Dial-Up Access
               Services using both the original telephone number and the new
               telephone number for a minimum of seven (7) calendar days after
               acceptance by Customer of the new number, and (ii) the total
               number of Dedicated Dial-Up Access Ports utilized for both
               telephone numbers shall at all times be equal to or greater than
               the total number of Dedicated Dial-Up Access Ports utilized for
               the original telephone number.

7.   SERVICE LEVELS FOR DIAL-UP ACCESS SERVICES

     This Article 7 sets forth the Service Levels that Vendor is required to
     meet or exceed pursuant to Article 7 of the Master Agreement, certain
     remedies for Vendor's failure to achieve the Service Levels, as well as
     terms and conditions with respect to Service Level reporting and
     adjustment. For each of the Service Levels set forth in this Article 7,
     scheduled maintenance by Vendor (or a third party) coordinated with
     Customer pursuant to Section 6.5(a) of this Schedule B will be excluded
     from the Service Level performance calculations.

     7.1. Service Levels.
          --------------

          Dial-Up Access Services provided under the Agreement shall be
          implemented with redundancy. In addition, any Dial-Up Access Port
          equipment locations in which Vendor provides Services other than the
          [*Material Omitted and Separately Filed Under an Application for
          Confidential Treatment] equipment locations existing as of the
          Effective Date [*Material Omitted and Separately Filed Under an
          Application for Confidential Treatment] sufficient to ensure
          [*Material Omitted and Separately Filed Under an

--------------------------------------------------------------------------------
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<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

          Application for Confidential Treatment] in the event of a [*Material
          Omitted and Separately Filed Under an Application for Confidential
          Treatment]

          (a)  Vendor Network Availability.
               ---------------------------

               (i)   "Network Availability" shall mean the percentage of the
                     time that each access device used to provide Dial-Up Access
                     Services is reachable through the Vendor Network from the
                     Customer's front-end hosts and vice-versa.

               (ii)  The Service Level applicable to Network Availability shall
                     be as follows: Network Availability for each calendar month
                     shall exceed [*Material Omitted and Separately Filed Under
                     an Application for Confidential Treatment] percent
                     ([*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] %). Vendor's
                     performance relative to such Service Level shall be
                     reported by Vendor on a monthly basis for each calendar
                     month.

               (iii) In the event that Network Availability is below [*Material
                     Omitted and Separately Filed Under an Application for
                     Confidential Treatment] percent ([*Material Omitted and
                     Separately Filed Under an Application for Confidential
                     Treatment] %) as measured in either [*Material Omitted and
                     Separately Filed Under an Application for Confidential
                     Treatment] or on a [*Material Omitted and Separately Filed
                     Under an Application for Confidential Treatment], such
                     event shall constitute a material breach of the Agreement.

          (b)  Average [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment] Percentage

               (i)   [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] Percentage for any
                     day of a calendar month is calculated as (A) the aggregate
                     number of [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment], during such
                     calendar day that result in a [*Material Omitted and
                     Separately Filed Under an Application for Confidential
                     Treatment] divided by (B) the aggregate number of such
                     [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] during such
                     calendar day. "Average [*Material Omitted and Separately
                     Filed Under an Application for Confidential Treatment]
                     Percentage" for any calendar month shall mean the
                     percentage-point aggregate of the [*Material Omitted and
                     Separately Filed Under an Application for Confidential
                     Treatment] Percentages calculated for each day of such
                     month, divided by the number of calendar days in such
                     month.

               (ii)  The Service Level applicable to Average [*Material Omitted
                     and Separately Filed Under an Application for Confidential
                     Treatment] Percentage shall be as follows: The Average
                     [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment]

--------------------------------------------------------------------------------
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<PAGE>

                     CONFIDENTIAL TREATMENT REQUESTED

                     Percentage for each calendar month of the Term shall not be
                     greater than [*Material Omitted and Separately Filed Under
                     an Application for Confidential Treatment] percentage
                     points above the corresponding [*Material Omitted and
                     Separately Filed Under an Application for Confidential
                     Treatment] for such month. Customer will provide reporting
                     to Vendor summarizing Vendor's performance with respect to
                     this Service Level.

               (iii) In the event that Vendor fails to meet the Service Level
                     corresponding to Average [*Material Omitted and Separately
                     Filed Under an Application for Confidential Treatment]
                     Percentage for each of [*Material Omitted and Separately
                     Filed Under an Application for Confidential Treatment]
                     calendar months, such [*Material Omitted and Separately
                     Filed Under an Application for Confidential Treatment]
                     shall constitute [*Material Omitted and Separately Filed
                     Under an Application for Confidential Treatment]. In the
                     event that Vendor fails to meet the Service Level
                     corresponding to Average [*Material Omitted and Separately
                     Filed Under an Application for Confidential Treatment]
                     Percentage by at least [*Material Omitted and Separately
                     Filed Under an Application for Confidential Treatment]
                     percentage points above the corresponding [*Material
                     Omitted and Separately Filed Under an Application for
                     Confidential Treatment] for each of [*Material Omitted and
                     Separately Filed Under an Application for Confidential
                     Treatment], then Customer may, at its option and in its
                     sole discretion, [*Material Omitted and Separately Filed
                     Under an Application for Confidential Treatment]. Vendor
                     shall be relieved of its obligation to meet the Service
                     Level applicable to Average [*Material Omitted and
                     Separately Filed Under an Application for Confidential
                     Treatment] Percentage to the extent that such failure is
                     caused by a significant change in the [*Material Omitted
                     and Separately Filed Under an Application for Confidential
                     Treatment] over the same period.

          (c)  Call Blocking.
               -------------

               (i)  "Call Blocking Event" means the occurrence of a Blocked Call
                    during the time when any Dedicated Dial-Up Access Port
                    corresponding to a telephone number is not being utilized.
                    "Blocked Call" means an attempted call, by Customer
                    equipment to a telephone number used to provide the Dial-Up
                    Access Services, to a Dedicated Dial-Up Access Port that
                    results in the return of a busy signal or other failure to
                    connect. Vendor shall provide to Customer reporting each
                    calendar day of each calendar month showing the usage of all
                    Dedicated Dial-Up Access Ports corresponding to each
                    telephone number used to provide Dial-Up Access Services in
                    [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment] increments. Using such reporting
                    and other information, Customer will measure daily the
                    number of Call Blocking Events; provided, however, that no
                    Dedicated Dial-Up Access Port shall account for more than
                    one Call Blocking

--------------------------------------------------------------------------------
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<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

                     Event until Vendor reports such Dedicated Dial-Up Access
                     Port is available or such Dedicated Dial-Up Access Port
                     actually becomes available.

               (ii)  The Service Level applicable to Call Blocking Events shall
                     be as follows: For any Call Blocking Event, Vendor shall
                     remedy the circumstances causing such event within
                     [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] hours after
                     Customer's notification of the same. Vendor's performance
                     relative to such Service Level shall be reported by
                     Customer on a monthly basis for each calendar month.

               (iii) In the event that the Vendor does not satisfy the Service
                     Level set forth in Subsection (ii) of this Subsection (c)
                     (i.e., the causes of the Call Blocking Event are not
                     remedied pursuant to Subsection (ii) of this Subsection
                     (c)), then Customer, as its sole and exclusive remedy,
                     shall [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] for the [*Material
                     Omitted and Separately Filed Under an Application for
                     Confidential Treatment] equal to (A) the aggregate number
                     of [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] for each[*Material
                     Omitted and Separately Filed Under an Application for
                     Confidential Treatment] that were not being utilized during
                     the period between the time that a [*Material Omitted and
                     Separately Filed Under an Application for Confidential
                     Treatment], multiplied by (B) [*Material Omitted and
                     Separately Filed Under an Application for Confidential
                     Treatment] for the corresponding [*Material Omitted and
                     Separately Filed Under an Application for Confidential
                     Treatment] occurred or persisted [*Material Omitted and
                     Separately Filed Under an Application for Confidential
                     Treatment].

          (d)  Training Failure Event Percentage.
               ---------------------------------

               (i)   "Training Failure Event" means, for any call by Customer
                     equipment to a Dedicated Dial-Up Access Port, the failure
                     of the modem devices utilized for such call to properly
                     complete modem handshake and negotiate a communications
                     session. "Training Failure Event Percentage" for any
                     telephone number means (A) the aggregate number of Training
                     Failure Events occurring during a calendar day for such
                     number, divided by (B) the aggregate number of calls by
                     Customer equipment to a Dedicated Dial-Up Access Port
                     corresponding to such telephone number during such day,
                     with the result expressed as a percentage. Vendor will
                     measure the occurrence of Training Failure Events, and will
                     calculate the Training Failure Event Percentage for each
                     day.

               (ii)  The Service Level applicable to Training Failure Event
                     Percentage shall be as follows: The Training Failure Event
                     Percentage for each calendar day of the Term shall be less
                     than [*Material Omitted and Separately

--------------------------------------------------------------------------------
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<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

                    Filed Under an Application for Confidential Treatment] for
                    such day.

          (e)  Ineffective Call Percentage.
               ---------------------------

               (i)   "Ineffective Call Percentage" means, for any calendar
                     month, the amount calculated as (A) the aggregate number of
                     calls that are successfully placed to an access device used
                     to provide Dial-Up Access Services but that are not able to
                     connect to Customer's front end host other than as a result
                     of problems with Customer's front-end host or Customer-
                     managed equipment, divided by (B) the aggregate number of
                     calls that are successfully placed to an access device used
                     to provide Dial-Up Access Services.

               (ii)  The Service Level applicable to Ineffective Call Percentage
                     shall be as follows: Ineffective Call Percentage for each
                     calendar month shall not exceed [*Material Omitted and
                     Separately Filed Under an Application for Confidential
                     Treatment] percent ([*Material Omitted and Separately Filed
                     Under an Application for Confidential Treatment]%).
                     Vendor's performance relative to such Service Level shall
                     be reported by Vendor on a daily basis.

          (f)  Customer Reported Problems.
               --------------------------

               (i)   "Customer Reported Problem" means any problem, reported by
                     a user of Customer's services, that is related to the Dial-
                     Up Access Services. "Customer Reported Problem Average" for
                     any calendar month means the average number of Customer
                     Reported Problems per one million user sessions during such
                     month.

               (ii)  The Service Level applicable to Customer Reported Problem
                     Average shall be as follows: The Customer Reported Problem
                     Average for each calendar month of the Term shall be less
                     than the corresponding [*Material Omitted and Separately
                     Filed Under an Application for Confidential Treatment] for
                     such month. Vendor's performance relative to such Service
                     Level shall be reported by Customer on a monthly basis for
                     each calendar month.

          (g)  Monthly Abnormal Disconnect Percentage.
               --------------------------------------

               (i)   "Daily Abnormal Disconnect Percentage" means, for each
                     calendar day of the Term, the amount calculated as (A) the
                     aggregate number of disconnected Dedicated Dial-Up Port
                     sessions during such day that are not initiated by a user
                     logoff sequence and that are caused by a problem with
                     respect to the Dial-Up Access Port or Vendor Network
                     between the access device used to provide Dial-Up Access
                     Services and the Vendor-managed Customer hub routers at
                     Customer's facilities, divided by (B) the aggregate number
                     of all Dedicated Dial-Up Port sessions commencing during
                     such calendar day, with the result expressed as a

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<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

                     percentage. "Monthly Abnormal Disconnect Percentage" means,
                     for each calendar month of the Term, the amount calculated
                     as (x) the percentage-point aggregate of the Daily Abnormal
                     Disconnect Percentages for such calendar month, divided by
                     (y) the aggregate number of calendar days in such calendar
                     month.

               (ii)  The Service Level applicable to Monthly Abnormal Disconnect
                     Percentage shall be as follows: Monthly Abnormal Disconnect
                     Percentage during a calendar month shall be less than
                     [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] percentage points
                     above the corresponding [*Material Omitted and Separately
                     Filed Under an Application for Confidential Treatment] for
                     such month. Vendor's performance relative to such Service
                     Level shall be reported by Customer on a monthly basis for
                     each calendar month.

               (iii) In the event that Vendor fails to meet the Service Level
                     corresponding to Monthly Abnormal Disconnect Percentage for
                     each of [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] such failure shall
                     constitute [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment]. In the event that
                     Vendor fails to meet the Service Level corresponding to
                     Monthly Abnormal Disconnect Percentage by at least
                     [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] percentage points
                     above the corresponding [*Material Omitted and Separately
                     Filed Under an Application for Confidential Treatment] for
                     each of [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] then Customer may,
                     at its option and its sole discretion, [*Material Omitted
                     and Separately Filed Under an Application for Confidential
                     Treatment] for this [*Material Omitted and Separately Filed
                     Under an Application for Confidential Treatment]. Vendor
                     shall be relieved of its obligation to meet the Service
                     Level applicable to Monthly Abnormal Disconnect Percentage
                     to the extent that such failure is caused by [*Material
                     Omitted and Separately Filed Under an Application for
                     Confidential Treatment] Average over the same period.

          (h)  Packet Loss Percentage.
               ----------------------

               (i)   "Packet Loss Percentage" means, for a calendar month, the
                     quantity calculated as (A) the aggregate number of data
                     packets dropped from the Vendor Network between the
                     Ethernet interface on an access device and the Vendor-
                     managed Customer hub routers during such month, divided by
                     (B) the aggregate number of all data packets introduced
                     into the Vendor Network between the Ethernet interface on
                     an access device and the Vendor-managed Customer hub
                     routers during such calendar month, the result expressed as
                     a percentage.

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<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

               (ii)  The Service Level applicable to Packet Loss Percentage
                     shall be as follows: Packet Loss Percentage for each
                     calendar month of the Term shall be less than [*Material
                     Omitted and Separately Filed Under an Application for
                     Confidential Treatment] percent ([*Material Omitted and
                     Separately Filed Under an Application for Confidential
                     Treatment]%) for such month. Vendor's performance relative
                     to such Service Level shall be reported by Vendor on a
                     monthly basis.

          (i)  Latency.
               -------

               (i)   "Latency" means the time interval between (A) the moment
                     when a ping is sent by Customer's PC equipment to a Dial-Up
                     Access Port equipment location, until (B) the moment when
                     the ping is returned to such PC equipment.

               (ii)  The Service Level applicable to Latency shall be as
                     follows: Average Latency for a calendar month shall be less
                     than the corresponding [*Material Omitted and Separately
                     Filed Under an Application for Confidential Treatment] for
                     such month. Vendor's performance relative to such Service
                     Level shall be reported by Customer on a monthly basis for
                     each calendar month.

          (j)  Time to Respond and Time to Restore Service Levels.
               --------------------------------------------------

               (i)   "Time to Respond" means the elapsed time between (i) the
                     time that Customer reports a problem to Vendor with respect
                     to the Services (or the time that Vendor otherwise becomes
                     aware of such a problem), until (ii) the moment that Vendor
                     notifies appropriate Customer personnel of such problem and
                     of those efforts being undertaken by Vendor to resolve such
                     problem. "Mean Time to Respond" for a calendar month shall
                     mean the average of all times corresponding to Time To
                     Respond during such calendar month. "Time to Restore" means
                     the elapsed time between (i) the time that Customer reports
                     a problem to Vendor with respect to the Services (or the
                     time that Vendor otherwise becomes aware of such a
                     problem), until (ii) the moment that the affected Services
                     are restored to normal operations in accordance with
                     applicable Service Levels, Acceptance Criteria and
                     Specifications. "Mean Time to Restore" for a calendar month
                     shall mean the average of all times corresponding to Time
                     To Repair during such calendar month. "Mean Maximum Time to
                     Restore" for a calendar month shall mean the average of all
                     of the maximum times corresponding to [*Material Omitted
                     and Separately Filed Under an Application for Confidential
                     Treatment] during such [*Material Omitted and Separately
                     Filed Under an Application for Confidential Treatment] plus
                     the [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment]. Vendor will not
                     close any problem ticket associated with a particular
                     problem until the appropriate Customer

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<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

                    representative and a Vendor representative agree that such
                    problem ticket may be closed.

               (ii) The Service Levels applicable to Mean Time to Respond and
                    Mean Time to Restore shall be as follows:

                    (1)  Mean Time to Respond for each calendar month shall be
                         less than [*Material Omitted and Separately Filed Under
                         an Application for Confidential Treatment] minutes;

                    (2)  Mean Time to Restore for each calendar month shall be
                         less than or equal to [*Material Omitted and Separately
                         Filed Under an Application for Confidential Treatment]
                         minutes;

                    (3)  Mean Maximum Time to Restore for each calendar month
                         shall be less than [*Material Omitted and Separately
                         Filed Under an Application for Confidential Treatment]
                         hours.

                    Vendor's performance relative to the foregoing Service
                    Levels shall be reported by Vendor on a monthly basis for
                    each calendar month.

     7.2. Failure to Perform.
          ------------------

          If Vendor fails to meet any Service Level, Vendor shall (a) promptly
          notify Customer of such failure (unless Customer first discovered and
          notified Vendor of such failure), (b) investigate and report on the
          causes of the failure; (c) advise Customer, as and to the extent
          requested by Customer, of the status of remedial efforts being
          undertaken with respect to such failure; (d) take commercially
          reasonable efforts to correct the failure, and begin meeting the
          Service Levels; and (e) take appropriate preventive measures to
          minimize the likelihood of the failure recurring. Notwithstanding the
          foregoing, Vendor's failure to use commercially reasonable efforts to
          meet or correct Service Level failures with respect to the [*Material
          Omitted and Separately Filed Under an Application for Confidential
          Treatment] in and of itself shall not constitute a breach of the
          Agreement. With respect to those Service Levels for which Vendor's
          performance is measured against [*Material Omitted and Separately
          Filed Under an Application for Confidential Treatment], Vendor shall
          not be deemed in breach of such Service Levels to the extent that
          Customer uses [*Material Omitted and Separately Filed Under an
          Application for Confidential Treatment] services provided by other
          [*Material Omitted and Separately Filed Under an Application for
          Confidential Treatment] with respect to such [*Material Omitted and
          Separately Filed Under an Application for Confidential Treatment] in
          such a manner that treats [*Material Omitted and Separately Filed
          Under an Application for Confidential Treatment] than similarly
          [*Material Omitted and Separately Filed Under an Application for
          Confidential Treatment] with respect to the calculation of [*Material
          Omitted and Separately Filed Under an Application for Confidential
          Treatment] relative to the calculation of the [*Material Omitted and
          Separately Filed Under an Application for Confidential Treatment].

     7.3. Reporting.
          ---------

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Schedule B                   Schedule B - Page 26
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

          Vendor shall provide Customer with the following reports, in a
          detailed format reasonably satisfactory to Customer:

          (a)  Usage Reports, including:

               (i)  Daily reports on [*Material Omitted and Separately Filed
                    Under an Application for Confidential Treatment] by
                    [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment] by [*Material Omitted and
                    Separately Filed Under an Application for Confidential
                    Treatment] and

               (ii) Daily reports on percentage of ineffective calls; and

          (b)  Daily reports on [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment] including [*Material
               Omitted and Separately Filed Under an Application for
               Confidential Treatment] and [*Material Omitted and Separately
               Filed Under an Application for Confidential Treatment].

          In addition, upon Customer's request, Vendor shall provide Customer
          with [*Material Omitted and Separately Filed Under an Application for
          Confidential Treatment] and other [*Material Omitted and Separately
          Filed Under an Application for Confidential Treatment] information for
          [*Material Omitted and Separately Filed Under an Application for
          Confidential Treatment] that are utilized to provide [*Material
          Omitted and Separately Filed Under an Application for Confidential
          Treatment] under this Schedule B. In addition, for all other
          components of the Vendor Network that are utilized to provide Dial-Up
          Access Services under this Schedule B, Vendor shall provide to
          Customer a daily report covering the [*Material Omitted and Separately
          Filed Under an Application for Confidential Treatment] as such data is
          collected by Vendor. In the event of a Network outage, Vendor will
          work cooperatively with Customer to share additional SNMP data which
          may be pertinent to the analysis and resolution of any such outage.

     7.4. Meetings.
          --------

          Vendor and Customer shall hold weekly meetings at Customer's site or
          via telephone conference call (unless otherwise requested by Customer)
          to assess Vendor's performance under this Schedule B. During emergency
          situations, meetings will be held at least on a daily basis.

     7.5. Periodic Review of Service Levels.
          ---------------------------------

          As requested by Customer or Vendor, Customer and Vendor shall review
          the Service Levels described in this Schedule B and shall make
          mutually agreed-upon adjustments to them as appropriate to reflect
          performance capabilities associated with advances in the technology
          and methods used to provide the Dial-Up Access Services.

8.   Pricing


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Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Schedule B                   Schedule B - Page 27
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

     This Article 8 describes the methodologies for calculating the charges
     under this Schedule B and relating pricing terms and conditions. The
     charges calculated pursuant to this Schedule B, and any other charges
     expressly set forth in the Master Agreement, shall fully compensate Vendor
     for the provision of the Dial-Up Access Services.

     8.1. Pricing for Dial-Up Access Services.
          -----------------------------------

          (a)  Monthly EDAP Charge.
               -------------------

               (i)  The monthly recurring charge (such charge, as may be
                    adjusted pursuant to the Agreement, the "Monthly EDAP
                    Charge") for one (1) Dedicated Dial-Up Access Port
                    corresponding to the first [*Material Omitted and Separately
                    Filed Under an Application for Confidential Treatment]
                    Dedicated Dial-Up Access Ports of the Dial-Up Purchase
                    Commitment only (such port an "Existing Dedicated Dial-Up
                    Access Port") shall be set at the Existing DAP Market Price,
                    as set forth in Exhibit B-2, and shall be automatically
                    reduced according to the schedule set forth in Exhibit B-2.
                    In addition, the Monthly EDAP Charge may be further reduced
                    as provided in this Article 8 of this Schedule B. The
                    Parties acknowledge that the Monthly EDAP Charge described
                    in the first sentence of Article 2 of Exhibit B-2 shall
                    apply retroactively to October 1, 1999, and Vendor shall
                    provide Customer with a refund of any amounts paid for the
                    corresponding Dial-Up Access Services in excess of such
                    price under the Original Agreement.

               (ii) Following a review of the applicable leases (but in no event
                    later than 45 days after the Effective Date), Vendor shall
                    inform Customer as to the extent to which it desires to (1)
                    assume the operating leases for certain modems, racks and
                    cables for the Existing Dedicated Dial-Up Access Ports
                    leased by Customer (collectively the "Leased Items"), and
                    (2) purchase certain modems, racks and cables for the
                    Existing Dedicated Dial-Up Access Ports owned by Customer
                    (collectively, the "Owned Items"). To the extent that the
                    Parties agree, the Parties shall enter into an amendment
                    under which (A) Vendor shall assume the operating leases for
                    the Leased Items, subject to the terms of such leases and to
                    the rights of third parties in such Leased Items, and (B)
                    Customer shall pass to Vendor title for the Owned Items
                    pursuant to economic terms to be mutually agreed upon,
                    subject to Customer's rights in such equipment. Such
                    amendment shall reflect that, with respect to Vendor's
                    assumption of the leases of the Leased Items, Customer will,
                    on a pass-through expense basis (i.e., without markup), pay
                    leasing costs as and when required under the terms of the
                    leases for the Leased Items. Such amendment shall also
                    reflect that any cost savings achieved by Vendor with
                    respect to leasing and capital costs for the Leased Items
                    will be shared equally between Customer and Vendor. If
                    Vendor decides not to assume the leases for the Leased
                    Items, the rights and obligations of the Parties with
                    respect to the Leased Items shall be as described in the
                    Original Agreement. If Vendor decides not to purchase the
                    Owned

--------------------------------------------------------------------------------
Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Schedule B                   Schedule B - Page 28
<PAGE>

                    Items, Customer shall continue to bear the actual capital
                    costs of the Owned Items in accordance with the terms of the
                    Original Agreement.

          (b)  Monthly DAP Charge.
               ------------------

               The monthly recurring charge (such charge, as may be reduced
               pursuant to the Agreement, the "Monthly DAP Charge") for one (1)
               Dedicated Dial-Up Access Port other than an Existing Dedicated
               Dial-Up Access Port shall be set at the DAP Initial Market Price,
               as set forth in Exhibit B-2, and shall be automatically reduced
               according to the schedule set forth in Exhibit B-2. In addition,
               the Monthly DAP Charge may be further reduced as provided in this
               Article 8 of Schedule B. The Monthly DAP Charge shall fully
               compensate Vendor for the provision of the corresponding Dial-Up
               Access Services (including all capital costs of providing the
               corresponding Dial-Up Access Services (excluding hub routers
               resident at Customer's data centers)).

          (c)  Additional Bandwidth.
               --------------------

               For each additional [*Material Omitted and Separately Filed Under
               an Application for Confidential Treatment] bps of average
               bandwidth available at peak per user outbound (and [*Material
               Omitted and Separately Filed Under an Application for
               Confidential Treatment] bps inbound) per Dedicated Dial-Up Access
               Port that Customer requests Vendor to provide hereunder, Vendor
               shall provide such additional bandwidth at a charge to Customer
               that is no greater than [*Material Omitted and Separately Filed
               Under an Application for Confidential Treatment] ($[*Material
               Omitted and Separately Filed Under an Application for
               Confidential Treatment]) per Dedicated Dial-Up Access Port per
               month for each additional [*Material Omitted and Separately Filed
               Under an Application for Confidential Treatment] bps of such
               bandwidth.

     8.2. Decommissioning of Dedicated Dial-Up Access Ports.
          -------------------------------------------------

          (a)  Beginning [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment], Customer may
               decommission Dedicated Dial-Up Access Ports that either
               contribute to the satisfaction of the Dial-Up Purchase Commitment
               or to Customer's satisfaction of its obligation described in
               Section 2.8(c)(ii) of this Schedule B, without liability, subject
               to the following:

               (i)  Customer will provide one hundred twenty (120) days prior
                    written notice of the calling areas in which Dedicated
                    Dial-Up Access Ports are to be decommissioned, as well as
                    the associated quantities of Dedicated Dial-Up Access Ports
                    to be decommissioned in each such area;

               (ii) the Vendor Decom Share for a calendar quarter shall not (in
                    the cumulative and not more than a de minimis amount) exceed
                    the Other Vendors' Decom Share for such quarter;

--------------------------------------------------------------------------------
Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Schedule B                   Schedule B - Page 29
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

               (iii) the decommissioning of Dedicated Dial-Up Access Ports
                     pursuant to this Subsection (a) shall not materially change
                     Customer's proportional distribution of Dedicated Dial-Up
                     Access Ports across Existing Calling Areas; and

               (iv)  if the decommissioning of Dedicated Dial-Up Access Ports
                     pursuant to this Subsection (a) causes the aggregate number
                     of Dial-Up Access Ports to fall below [*Material Omitted
                     and Separately Filed Under an Application for Confidential
                     Treatment] of the number of Dedicated Dial-Up Access Ports
                     comprising the Dial-Up Purchase Commitment, then Vendor
                     may, upon six months' prior notice to Customer, [*Material
                     Omitted and Separately Filed Under an Application for
                     Confidential Treatment], Vendor shall provide Transition
                     Assistance pursuant to Section 13.4 of the Master
                     Agreement.

          (b)  Customer may decommission any Dedicated Dial-Up Access Ports
               other than those to which Subsection (a) of this Section applies
               (including (A) any Dedicated Dial-Up Access Ports ordered at any
               time for delivery after [*Material Omitted and Separately Filed
               Under an Application for Confidential Treatment], and (B) any
               Dedicated Dial-Up Access Ports ordered in excess of those
               necessary to satisfy the Dial-Up Purchase Commitment), without
               liability and as of a decommissioning date specified by Customer
               upon one hundred twenty (120) days' prior written notice to
               Vendor; provided, however, that Customer may decommission
               Dedicated Dial-Up Access Ports pursuant this Subsection only to
               the extent that the first day of the month in which Final
               Acceptance occurred for such ports is at least twelve (12) months
               prior to the decommissioning date requested by Customer pursuant
               to this Subsection (b).

          (c)  Customer shall not be responsible for any charges for a Dedicated
               Dial-Up Access Port to the extent such charges correspond to the
               time after the requested decommissioning date of which Customer
               provides Vendor with notification pursuant to this Schedule B.

     8.3. Adjustments to Pricing for Dial-Up Access Services.
          --------------------------------------------------

          (a)  New Dial-Up Market Price.
               ------------------------

               (i)  Definitions.

                    (1)  "New Dial-Up Market Price" for any Dial-Up Access shall
                         mean the price [*Material Omitted and Separately Filed
                         Under an Application for Confidential Treatment] to
                         Customer by any Dial-Up Market Vendor for Comparable
                         Dial-Up Services. To calculate the New Dial-Up Market
                         Price pursuant to this Subsection, the price for
                         [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] shall be
                         reasonably adjusted to reflect the difference between
                         the [*Material Omitted and Separately

--------------------------------------------------------------------------------
Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Schedule B                   Schedule B - Page 30
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

                         Filed Under an Application for Confidential Treatment]
                         and the provision of [*Material Omitted and Separately
                         Filed Under an Application for Confidential Treatment]
                         by a [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] that (A) do not
                         include [*Material Omitted and Separately Filed Under
                         an Application for Confidential Treatment], (B) do not
                         include [*Material Omitted and Separately Filed Under
                         an Application for Confidential Treatment] to such
                         vendor for [*Material Omitted and Separately Filed
                         Under an Application for Confidential Treatment], or
                         (C) do not include [*Material Omitted and Separately
                         Filed Under an Application for Confidential Treatment]
                         to such vendor for [*Material Omitted and Separately
                         Filed Under an Application for Confidential Treatment].

                    (2)  "Dial-Up Market Vendor" shall mean a vendor (not
                         including a Special Affiliate) that at any time
                         [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] at least
                         [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment]. For the
                         purpose of this Subsection, Special Affiliate shall
                         only be deemed to include Subsections (i) and (ii) of
                         the definition of "Special Affiliate" in Schedule A.

               (ii) Notification Process.

                    Customer may provide Vendor with notice at any time of a New
                    Dial-Up Market Price (each such notice, a "New Dial-Up
                    Market Price Notice" and the date of such notice as
                    determined pursuant to Section 16.4 of the Master Agreement,
                    the "New Dial-Up Market Price Notice Date"). Each New
                    Dial-Up Market Price Notice will contain (A) the New Dial-Up
                    Market Price calculation and [*Material Omitted and
                    Separately Filed Under an Application for Confidential
                    Treatment] of the[*Material Omitted and Separately Filed
                    Under an Application for Confidential Treatment] to which
                    such New Dial-Up Market Price relates and (B) information
                    sufficient to enable Vendor to match the average [*Material
                    Omitted and Separately Filed Under an Application for
                    Confidential Treatment] per [*Material Omitted and
                    Separately Filed Under an Application for Confidential
                    Treatment] at [*Material Omitted and Separately Filed Under
                    an Application for Confidential Treatment] corresponding to
                    the New Dial-Up Market Price if requested by Customer. No
                    later than thirty (30) calendar days after the New Dial-Up
                    Market Price Notice Date corresponding to a New Dial-Up
                    Market Price Notice, Vendor will respond to Customer by
                    notifying Customer in writing whether it will:


--------------------------------------------------------------------------------
Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Schedule B                   Schedule B - Page 31
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

                    (1)  accept the validity of the proposed New Dial-Up Market
                         Price and reduce prices to the applicable New Dial-Up
                         Market Price in accordance with Subsection (iii) of
                         this Subsection (a),

                    (2)  accept the validity of the proposed New Dial-Up Market
                         Price and decline to reduce prices to the New Dial-Up
                         Market Price in accordance with the corresponding New
                         Dial-Up Market Price Notice, or

                    (3)  dispute the validity of the proposed New Dial-Up Market
                         Price.

                    (each a "New Dial-Up Market Price Response"). Vendor shall
                    not unreasonably dispute the validity of a proposed New
                    Dial-Up Market Price.

              (iii) Reduction Process.

                    In the event Vendor accepts a proposed New Dial-Up Market
                    Price pursuant to clause (1) of Subsection (ii) of this
                    Subsection (a), then:

                    (1)  Effective as of the Incremental New Ports MP Change
                         Date, the Monthly DAP Charge for all [*Material Omitted
                         and Separately Filed Under an Application for
                         Confidential Treatment] delivered on or after
                         [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] Date will be
                         reduced to the New Dial-Up Market Price set forth in
                         the corresponding New Dial-Up Market Price Notice, and
                         with respect to such New Ports, Vendor will, if
                         requested by Customer, [*Material Omitted and
                         Separately Filed Under an Application for Confidential
                         Treatment] per [*Material Omitted and Separately Filed
                         Under an Application for Confidential Treatment] at
                         [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] provided for
                         the [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] Services
                         corresponding to such New Dial-Up Market Price.

                    (2)  Effective as of the All New Ports MP Change Date, the
                         Monthly DAP Charge for all [*Material Omitted and
                         Separately Filed Under an Application for Confidential
                         Treatment] (regardless of when delivered) will be
                         reduced to the New Dial-Up Market Price set forth in
                         the corresponding [*Material Omitted and Separately
                         Filed Under an Application for Confidential Treatment]
                         Notice and with respect to such New Ports, Vendor will,
                         if requested by Customer, [*Material Omitted and
                         Separately Filed Under an Application for Confidential
                         Treatment] available per [*Material Omitted and
                         Separately Filed Under an Application for Confidential

--------------------------------------------------------------------------------
Network Services Agreement   America Online, Inc. / BBN Corporation CONFIDENTIAL
Schedule B                  Schedule B - Page 32
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

                         Treatment] for the [*Material Omitted and Separately
                         Filed Under an Application for Confidential Treatment]
                         Services corresponding to such [*Material Omitted and
                         Separately Filed Under an Application for Confidential
                         Treatment].

                    (3)  Effective as of the Base Port MP Change Date, the
                         Monthly EDAP Charge for all [*Material Omitted and
                         Separately Filed Under an Application for Confidential
                         Treatment] and the Monthly [*Material Omitted and
                         Separately Filed Under an Application for Confidential
                         Treatment] regardless of when delivered will be reduced
                         to the New Dial-Up Market Price set forth in the
                         corresponding New Dial-Up Market Price Notice, and with
                         respect to such New Ports and Existing Dial-Up Access
                         Ports, Vendor will, if requested by Customer, match the
                         [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] available per
                         [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] for the
                         [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] Services
                         corresponding to such New Dial-Up Market Price.

                    Notwithstanding the foregoing:

                    (4)  If Vendor accepts the validity of a proposed New
                         Dial-Up Market Price and reduces prices to the
                         applicable New Dial-Up Access Market Price in a given
                         calendar year, then Vendor shall not be obligated to
                         provide Customer with any additional New Dial-Up Market
                         Price Response with respect to any New Dial-Up Market
                         Price Notice for which the corresponding New Dial-Up
                         Market Price Effective Date occurs in such calendar
                         year.

                    (5)  Vendor shall not be obligated to reduce the Monthly DAP
                         Charge or the Monthly EDAP Charge, as the case may be,
                         at a rate that is[*Material Omitted and Separately
                         Filed Under an Application for Confidential Treatment]
                         than the rate at which [*Material Omitted and
                         Separately Filed Under an Application for Confidential
                         Treatment] provides [*Material Omitted and Separately
                         Filed Under an Application for Confidential Treatment]
                         relative to the applicable[*Material Omitted and
                         Separately Filed Under an Application for Confidential
                         Treatment] as measured monthly. For example, if the
                         [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] has committed
                         to provide [*Material Omitted and Separately Filed
                         Under an Application for Confidential Treatment] or
                         more [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] at the
                         [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] but immediately
                         following the [*Material Omitted and Separately Filed
                         Under an Application for Confidential Treatment] the
                         [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] or the
                         [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] as applicable,
                         the [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] has only
                         provided [*Material Omitted and Separately Filed Under
                         an Application for Confidential Treatment] at the
                         [*Material Omitted and

--------------------------------------------------------------------------------
Network Services Agreement   America Online, Inc. / BBN Corporation CONFIDENTIAL
Schedule B                  Schedule B - Page 33
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

                         Separately Filed Under an Application for Confidential
                         Treatment], then Vendor will only be obligated to
                         reduce the Monthly DAP Charge or Monthly EDAP Charge,
                         as the case may be, for [*Material Omitted and
                         Separately Filed Under an Application for Confidential
                         Treatment] of the [*Material Omitted and Separately
                         Filed Under an Application for Confidential Treatment]
                         as of the applicable month that are subject
                         to[*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] at that time
                         [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] delivered on or
                         after the [*Material Omitted and Separately Filed Under
                         an Application for Confidential Treatment] as of such
                         date, of all[*Material Omitted and Separately Filed
                         Under an Application for Confidential Treatment] and of
                         all [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment]. If during the
                         following month [*Material Omitted and Separately Filed
                         Under an Application for Confidential Treatment] has
                         provided an additional [*Material Omitted and
                         Separately Filed Under an Application for Confidential
                         Treatment] at the [*Material Omitted and Separately
                         Filed Under an Application for Confidential Treatment],
                         then Vendor will be obligated to reduce the Monthly DAP
                         Charge or Monthly EDAP Charge, as the case may be,
                         [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] as of the
                         applicable month that are subject to a [*Material
                         Omitted and Separately Filed Under an Application for
                         Confidential Treatment] at that time (i.e., for
                         [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] delivered on or
                         after the [*Material Omitted and Separately Filed Under
                         an Application for Confidential Treatment] as of such
                         date, of all[*Material Omitted and Separately Filed
                         Under an Application for Confidential Treatment] as of
                         the [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] as of the
                         [*Material Omitted and

--------------------------------------------------------------------------------
Network Services Agreement   America Online, Inc. / BBN Corporation CONFIDENTIAL
Schedule B                  Schedule B - Page 34
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

                         Separately Filed Under an Application for Confidential
                         Treatment].

                    (6)  Vendor shall not be obligated to [*Material Omitted and
                         Separately Filed Under an Application for Confidential
                         Treatment] per[*Material Omitted and Separately Filed
                         Under an Application for Confidential Treatment]
                         at[*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] for
                         the[*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] corresponding
                         to a New Dial-Up Market Price at a rate that is
                         [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] than the rate
                         in which the [*Material Omitted and Separately Filed
                         Under an Application for Confidential Treatment]
                         provides [*Material Omitted and Separately Filed Under
                         an Application for Confidential Treatment]
                         per[*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] at [*Material
                         Omitted and Separately Filed Under an Application for
                         Confidential Treatment] for Comparable Dial-Up Services
                         relative to the applicable Dial-Up Market Vendor
                         Trigger, as measured monthly.

                    (7)  [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] shall be
                         applicable only during such periods as [*Material
                         Omitted and Separately Filed Under an Application for
                         Confidential Treatment] at such [*Material Omitted and
                         Separately Filed Under an Application for Confidential
                         Treatment], or a[*Material Omitted and Separately Filed
                         Under an Application for Confidential Treatment] from
                         a[*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment].

               (iv) Decommissioning Process.

                    If Vendor declines to reduce the Monthly DAP Charge or the
                    Monthly EDAP Charge to the New Dial-Up Market Price pursuant
                    to clause (2) of Subsection (ii) of this Subsection (a),
                    then Customer may, in its sole discretion, do either or both
                    of the following: (A) terminate the Dial-Up Purchase
                    Commitment, and (B) decommission Dedicated Dial-Up Access
                    Ports, subject to the following restrictions:

                    (1)  Customer will provide [*Material Omitted and Separately
                         Filed Under an Application for Confidential Treatment]
                         days prior written notice of the calling areas in which
                         Dedicated Dial-Up Access Ports are to be
                         decommissioned, as well as the

--------------------------------------------------------------------------------
Network Services Agreement   America Online, Inc. / BBN Corporation CONFIDENTIAL
Schedule B                  Schedule B - Page 35
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

                         associated quantities of Dedicated Dial-Up Access Ports
                         to be decommissioned in each such area;

                    (2)  Customer may only decommission a number of Dedicated
                         Dial-Up Access Ports no greater than the number of
                         Dedicated Dial-Up Access Ports that are provided to
                         [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] by other
                         [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] at or below
                         such[*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment].

                    (3)  The effective date of decommission applicable to a
                         Existing Dial-Up Access Port shall not be earlier than
                         [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment].

                    (4)  The decommissioning of Dedicated Dial-Up Access Ports
                         pursuant to this Subsection (iv) shall result in the
                         same approximate weighted distribution of Dedicated
                         Dial-Up Access Ports across Existing Calling Areas.

                    (5)  The right to decommission arising from any particular
                         New Dial-Up Market Price Notice shall cease, on a
                         prospective basis if and when Vendor delivers a New
                         Dial-Up Market Price Response, in response to a later
                         New Dial-Up Market Price Notice, accepting a proposed
                         New Dial-Up Market Price pursuant to clause (1) of
                         Subsection (ii) of this Subsection (a) .

               (v)  Dispute Resolution Process.

                    If Vendor reasonably disputes the validity of the New
                    Dial-Up Market Price pursuant to clause (3) of Subsection
                    (ii) of this Subsection (a), then each Party shall promptly
                    escalate to the senior-executive level all efforts by such
                    Party to resolve such dispute.

               (vi) Example.

                    For example:

                    (1)  If Customer provides Vendor with a New Dial-Up Market
                         Price Notice for which the New Dial-Up Market Price
                         Notice Date is [*Material Omitted and Separately Filed
                         Under an Application for Confidential Treatment], and
                         Vendor accepts the proposed New Dial-Up Market Price
                         pursuant to clause (A) of Subsection (ii) of this
                         Subsection (a), then (x) the New Dial-Up Market Price
                         Effective Date would be [*Material Omitted and
                         Separately Filed Under an Application for Confidential
                         Treatment], and (y) pursuant to Schedule A, the
                         Incremental


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Network Services Agreement   America Online, Inc. / BBN Corporation CONFIDENTIAL
Schedule B                  Schedule B - Page 36
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

                         New Ports MP Change Date would be [*Material Omitted
                         and Separately Filed Under an Application for
                         Confidential Treatment], the All New Ports MP Change
                         Date would be [*Material Omitted and Separately Filed
                         Under an Application for Confidential Treatment], and
                         the Base Port MP Change Date would be [*Material
                         Omitted and Separately Filed Under an Application for
                         Confidential Treatment].

                    (2)  Pursuant to Subsection (iii)(1) of this Subsection (a),
                         and except as otherwise required pursuant to the
                         restrictions described in Subsections (iii)(5),
                         (iii)(6), and (iii)(7) of this Subsection (a), as of
                         [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment], the Monthly
                         DAP Charge for all[*Material Omitted and Separately
                         Filed Under an Application for Confidential Treatment]
                         delivered on or after [*Material Omitted and Separately
                         Filed Under an Application for Confidential Treatment]
                         would be reduced to the New Dial-Up Market Price set
                         forth in the corresponding New Dial-Up Market Price
                         Notice, and with respect to such [*Material Omitted and
                         Separately Filed Under an Application for Confidential
                         Treatment], Vendor would, if requested by Customer,
                         [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] per[*Material
                         Omitted and Separately Filed Under an Application for
                         Confidential Treatment] at peak provided for the
                         [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] corresponding
                         to such New Dial-Up Market Price. Pursuant to
                         Subsection (iii)(4) of this Subsection (a), Vendor
                         would not be obligated to provide Customer with any
                         additional New Dial-Up Market Price Response with
                         respect to any New Dial-Up Market Price Notice for
                         which the corresponding New Dial-Up Market Price
                         Effective Date occurs in [*Material Omitted and
                         Separately Filed Under an Application for Confidential
                         Treatment].

                    (3)  Pursuant to Subsection (iii)(2) of this Subsection (a),
                         as of [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment], the Monthly
                         DAP Charge for all [*Material Omitted and Separately
                         Filed Under an Application for Confidential Treatment]
                         regardless of when delivered would be reduced to the
                         New Dial-Up Market Price set forth in the corresponding
                         New Dial-Up Market Price Notice, and with respect to
                         such [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment], Vendor would,
                         if requested by Customer, [*Material Omitted and
                         Separately Filed Under an Application for Confidential
                         Treatment] per [*Material

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                       CONFIDENTIAL TREATMENT REQUESTED

                         Omitted and Separately Filed Under an Application for
                         Confidential Treatment] at [*Material Omitted and
                         Separately Filed Under an Application for Confidential
                         Treatment] for the [*Material Omitted and Separately
                         Filed Under an Application for Confidential Treatment]
                         corresponding to such New Dial-Up Market Price. Such
                         reduction would not be inconsistent with Subsection
                         (iii)(4) of this Subsection (a), because such reduction
                         was made pursuant to the same New Dial-Up Market Price
                         Notice that reduced the Monthly DAP Charge pursuant to
                         Subsection (2) of this Subsection (vi).

                    (4)  Pursuant to Subsection (iii)(3) of this Subsection (a),
                         as of [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] and the
                         [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] for all
                         [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] regardless of
                         when delivered will be reduced to the New Dial-Up
                         Market Price set forth in the corresponding New Dial-Up
                         Market Price Notice, and with respect to such all
                         [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment], Vendor will,
                         if requested by Customer, [*Material Omitted and
                         Separately Filed Under an Application for Confidential
                         Treatment] per [*Material Omitted and Separately Filed
                         Under an Application for Confidential Treatment] at
                         [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] corresponding
                         to such New Dial-Up Market Price.

                    (5)  If Customer provides Vendor with another New Dial-Up
                         Market Price Notice for which the New Dial-Up Market
                         Price Notice Date is [*Material Omitted and Separately
                         Filed Under an Application for Confidential Treatment],
                         Vendor would be obligated to provide Customer with a
                         New Dial-Up Market Price Response pursuant to
                         Subsection (ii) of this Subsection. Such obligation
                         would not be contrary to Subsection (iii)(4) of this
                         Subsection (a), because the New Dial-Up Market Price
                         Effective Date for such New Dial-Up Market Price Notice
                         would be [*Material Omitted and Separately Filed Under
                         an Application for Confidential Treatment]. If Vendor
                         accepts such proposed New Dial-Up Market Price pursuant
                         to clause (1) of Subsection (ii) of this Subsection
                         (a), then effective [*Material Omitted and Separately
                         Filed Under an Application for Confidential Treatment],
                         the Monthly DAP Charge for [*Material Omitted and
                         Separately Filed Under an Application for Confidential
                         Treatment] regardless of

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                       CONFIDENTIAL TREATMENT REQUESTED

                         when delivered would be reduced to such New Dial-Up
                         Market Price, and with respect to such [*Material
                         Omitted and Separately Filed Under an Application for
                         Confidential Treatment], Vendor would, if requested by
                         Customer, [*Material Omitted and Separately Filed Under
                         an Application for Confidential Treatment] per
                         [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] at [*Material
                         Omitted and Separately Filed Under an Application for
                         Confidential Treatment] for the [*Material Omitted and
                         Separately Filed Under an Application for Confidential
                         Treatment] corresponding to such New Dial-Up Market
                         Price. Further, pursuant to Subsection (iii)(3) of this
                         Subsection (a), as of [*Material Omitted and Separately
                         Filed Under an Application for Confidential Treatment],
                         the Monthly EDAP Charge will be reduced to such New
                         Dial-Up Market Price, and with respect to [*Material
                         Omitted and Separately Filed Under an Application for
                         Confidential Treatment], Vendor will, if requested by
                         Customer, [*Material Omitted and Separately Filed Under
                         an Application for Confidential Treatment] per
                         [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] at [*Material
                         Omitted and Separately Filed Under an Application for
                         Confidential Treatment] or the [*Material Omitted and
                         Separately Filed Under an Application for Confidential
                         Treatment] corresponding to such New Dial-Up Market
                         Price.

          (b)  Most-Favored Customer.
               ---------------------

               (i)  As long as the aggregate number of Dial-Up Access Ports then
                    being purchased or ordered by Customer exceeds that of any
                    other customer of Vendor, Vendor shall not provide dial-up
                    access services that are Comparable Dial-Up Services to any
                    other Applicable DUP Purchaser (1) at prices that are lower
                    than those charged or available to Customer under this
                    Agreement, and for a [*Material Omitted and Separately Filed
                    Under an Application for Confidential Treatment] , or for
                    [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment] that are in the aggregate equal
                    to or less than the [*Material Omitted and Separately Filed
                    Under an Application for Confidential Treatment] that
                    [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment] hereunder or (2) pursuant to
                    terms and conditions more favorable to such Applicable DUP
                    Purchaser than the terms and conditions of this Schedule B
                    and Master Agreement, in each case, without first offering
                    such lower price and other more favorable terms and
                    conditions to Customer, within thirty (30) calendar days of
                    contractually committing to such price and other terms with
                    another customer. As of the Effective Date, Vendor

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                       CONFIDENTIAL TREATMENT REQUESTED

                    acknowledges that the aggregate number of Dial-Up Access
                    Ports being purchased or ordered by Customer exceeds that of
                    any other customer of Vendor. In the event that the
                    aggregate number of Dial-Up Access Ports being purchased or
                    ordered by Customer at any time during the Term does not
                    exceed that of any other customer of Vendor, Vendor shall
                    provide Customer with written notification of such event
                    within thirty (30) calendar days of the occurrence of such
                    event. For the purposes of this Subsection, prices "charged
                    or available to Customer hereunder" for Dedicated Dial-Up
                    Access Ports shall be determined by [*Material Omitted and
                    Separately Filed Under an Application for Confidential
                    Treatment] the applicable [*Material Omitted and Separately
                    Filed Under an Application for Confidential Treatment] and
                    [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment] in proportion to the number of
                    [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment] and [*Material Omitted and
                    Separately Filed Under an Application for Confidential
                    Treatment] or [*Material Omitted and Separately Filed Under
                    an Application for Confidential Treatment] by [*Material
                    Omitted and Separately Filed Under an Application for
                    Confidential Treatment]. "Applicable DUP Purchaser" shall
                    mean any party (including any Vendor Affiliate that resells
                    Dial-Up Access purchased from Vendor or another Vendor
                    Affiliate) that is obligated to purchase, that actually
                    purchases, or that seeks to purchase from Vendor or its
                    Affiliates Dial-Up Access at any time equivalent to more
                    than [*Material Omitted and Separately Filed Under an
                    Application for Confidential Treatment] Dial-Up Access
                    Ports.

               (ii) As long as the aggregate number of Dial-Up Access Ports then
                    being purchased or ordered by Customer exceeds that of any
                    other customer of Vendor, to the extent that Vendor provides
                    dial-up access services that are not [*Material Omitted and
                    Separately Filed Under an Application for Confidential
                    Treatment, then Vendor shall offer, on a quarterly basis, to
                    provide to Customer such dial-up access services at the
                    prices charged or available to, and upon the terms and
                    conditions applicable to, [*Material Omitted and Separately
                    Filed Under an Application for Confidential Treatment];
                    provided, however, that if Customer's service requirements
                    would necessitate changes to such terms and conditions, the
                    Parties shall work in good faith to adjust such terms and
                    conditions as mutually agreed to satisfy such requirements.
                    To the extent that Customer accepts such offer of dial-up
                    access services that are not [*Material Omitted and
                    Separately Filed Under an Application for Confidential
                    Treatment] from Vendor, Vendor shall provide such services
                    as ordered by Customer pursuant to a separate Schedule to
                    the Master Agreement, such services shall be deemed Services
                    to which the Master Agreement applies, such services shall
                    be subject to most-favored customer terms and conditions
                    substantially similar to those set forth in this Subsection
                    (b), and Customer may [*Material Omitted and Separately
                    Filed Under an Application for

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                       CONFIDENTIAL TREATMENT REQUESTED

                    Confidential Treatment]. In the event of [*Material Omitted
                    and Separately Filed Under an Application for Confidential
                    Treatment], Customer shall have no further liability to
                    Vendor with respect to such portion of the Dial-Up Purchase
                    Commitment replaced pursuant to this Subsection (ii).

              (iii) As long as the aggregate number of Dial-Up Access Ports
                    then being purchased or ordered by Customer exceeds that of
                    any other customer of Vendor, Vendor shall offer to
                    Customer, Comparable Dial-Up Services provided or offered by
                    any Vendor Affiliate to an Applicable DUP Purchaser (1) at
                    prices that are equal to or lower than those charged or
                    available to such Applicable DUP Purchaser for such
                    services, for a commitment by such Applicable DUP Purchaser
                    to order or purchase volumes, or for actual orders or
                    purchases of volumes, that are in the aggregate equal to or
                    less than the equivalent volumes that Customer is obligated
                    to purchase under the Agreement, and (2) pursuant to terms
                    and conditions that are at least as favorable or more
                    favorable to Customer than the terms and conditions
                    applicable to or available to an Applicable DUP Purchaser.

               (iv) For any price proposal made by Vendor to Customer at any
                    time during the Term, Vendor shall in good faith represent
                    to Customer in writing whether or not such proposal is being
                    made for reasons that include Vendor's belief that an
                    adjustment may be required pursuant to this Subsection (b).

               (v)  Customer may audit Vendor's compliance with this Subsection
                    (b) pursuant to Article 10 of the Master Agreement. In the
                    event that Vendor fails to comply with this Subsection (b)
                    (e.g., fails to adjust pricing in accordance with this
                    Subsection (b)), then Vendor shall rebate to Customer, with
                    respect to each Dedicated Dial-Up Access Port purchased
                    hereunder, the difference between (1) the price actually
                    paid by Customer hereunder, and (2) the lower price provided
                    to the third party purchasing the Comparable Dial-Up
                    Services from Vendor, retroactive to the date Vendor
                    provided the lower price to such third party, together with
                    interest computed in the same manner as described in Section
                    9.2 of the Master Agreement on such rebated amounts from
                    such date.

          (c)  Regulatory Changes Affecting Pricing.
               ------------------------------------

               In the event that any change in applicable Federal regulations
               results in a significant, demonstrable change in Vendor's costs
               to provide the Dial-Up Access Services, then:

               (i)  in the case of a cost increase, Vendor may pass such
                    applicable cost increase along to Customer on an
                    Out-of-Pocket Expense basis so long as such increase is
                    passed along to all of Vendor's other Dial-Up Access

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                    customers to which such costs are not prohibited from being
                    passed; provided, however, Customer may elect, with 120 days
                    notice, to decommission in accordance with Subsection
                    (a)(iv) of this Section any of the Dial-Up Access Ports
                    affected by such Federal regulatory cost increase (however,
                    Customer shall not be required to pay such cost increase
                    during the 120-day decommissioning notice period); provided
                    further, however, that (A) the decommissioning of Dedicated
                    Dial-Up Access Ports across the Vendor Network pursuant to
                    this Subsection shall be in proportion to the approximate
                    weighted distribution of Dedicated Dial-Up Access Ports
                    across Existing Calling Areas, and (B) the date and,
                    proportional rate restrictions on decommissioning in
                    Subsection (a)(iv) of this Section shall not apply with
                    respect to decommissioning under this Section; and

               (ii) in the event of a cost decrease, Vendor shall pass such
                    decrease to Customer.

               In connection with any such increase or decrease, Vendor shall
               identify the Dial-Up Access Ports affected by such regulatory
               cost change and the amount of the applicable change to the
               Monthly EDAP Charge or Monthly DAP Charge for such affected
               Dial-Up Access Ports. Any such regulatory cost change passed
               -through to Customer shall take effect as of the first day of the
               calendar month immediately following delivery of the regulatory
               cost change notice and shall continue in effect until the date on
               which the next New Dial-Up Market Price becomes applicable to
               such affected Dial-Up Access Ports.

     8.4. Normalization Methodology And Conversion Of Services.
          ----------------------------------------------------

          (a)  Normalization Methodology.
               -------------------------

               For purposes of Sections 2.8(c) and 8.3(b)(ii) of this Schedule
               B, and for purposes of the definitions of "Other Vendors' Decom
               Share" and "Vendor's Decom Share" set forth in Schedule A, in
               order to normalize a commitment to order or purchase dial-up
               access provided on a usage basis with a commitment to order or
               purchase Dedicated Dial-Up Access Ports provided under this
               Agreement, a commitment to order or purchase [*Material Omitted
               and Separately Filed Under an Application for Confidential
               Treatment] shall be deemed equivalent to a commitment to purchase
               one (1) Dedicated Dial-Up Access Port for such month (such
               conversion methodology collectively the "Normalization
               Methodology").

          (b)  Conversion of Services.
               ----------------------

               Upon Customer's request, Vendor shall reasonably and in good
               faith discuss with Customer without further obligation the
               modification of the pricing methodologies applicable to the
               Dial-Up Access Services that may be purchased by Customer under
               this Schedule B as necessary to convert certain Dial-Up Access
               Services to hourly or similar usage based pricing.

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                       CONFIDENTIAL TREATMENT REQUESTED

     8.5. Technological Change.
          --------------------

          Vendor acknowledges that quality of the Dial-Up Access Services is
          critical to the satisfaction of the users of Customer's services and
          will work to minimize any quality issues associated with the rapid
          implementation of new service technologies.

          (a)  Changes in Dial-Up Access Platform.
               ----------------------------------

               (i)  In the event that Vendor determines that an access platform
                    different from that which is used as of the Effective Date
                    to provide Dedicated Dial-Up Access Ports to Customer
                    represents a superior value, or otherwise may make such
                    platform desirable, Vendor may utilize such different access
                    technology; provided, however, that:

               (ii) Vendor shall provide Customer with notification of such
                    different access technology upon Vendor's determination to
                    utilize such different access technology, which notice shall
                    be provided no less than sixty (60) days' before deploying
                    such change;

              (iii) such different access technology is not utilized in
                    conjunction with then-existing access technology for any
                    given telephone number for more than forty-five (45) days;
                    and

               (iv) if such different access technology does not provide (or
                    enable Vendor to provide) any reports required under Section
                    6.3(o) or 7.3(a) of this Schedule B other than the reports
                    described in Section 7.3(a)(i) of this Schedule B, then:

                    (1)  Vendor may deploy not more than [*Material Omitted and
                         Separately Filed Under an Application for Confidential
                         Treatment] such Dedicated Dial-Up Access Ports (in the
                         aggregate for all such different access technologies
                         that do not provide such reports) (each of such ports a
                         "Reportless Port");

                    (2)  with respect to any Reportless Port, Vendor shall use
                         all commercially reasonable efforts to provide such
                         reports as soon as practicable, but in no event later
                         than [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] after
                         acceptance of such Reportless Port; and

                    (3)  if Vendor is unable to provide such reports for a
                         Reportless Port for [*Material Omitted and Separately
                         Filed Under an Application for Confidential Treatment]
                         days of acceptance of such Reportless Port, then Vendor
                         shall immediately remove from service any such
                         Reportless Port.

               In no event shall Vendor provide any Dedicated Dial-Up Access
               Ports that do not provide the reports described in Section
               7.3(a)(i) of this Schedule B. Upon the request of Customer,
               Vendor shall identify which access platform is then

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                       CONFIDENTIAL TREATMENT REQUESTED

               being utilized for each telephone number used to provide
               Dedicated Dial-Up Access Ports.

          (b)  Technology Briefing.
               -------------------

               Vendor will provide Customer with a semi-annual technology
               briefing detailing Vendor's near- and medium- term plans for the
               introduction of new technology and new Internet-related services.
               Information exchanged by the Parties in conjunction with such
               briefing shall be deemed Confidential Information for the
               purposes of the Agreement.

9.   SPECIFICATIONS AND ACCEPTANCE CRITERIA

     9.1. Specifications.
          --------------

          Dedicated Dial-Up Access Ports provided hereunder shall fully conform
          with the following Specifications (collectively, the "Dial-Up Access
          Specifications"):

          (a)  By [*Material Omitted and Separately Filed Under an Application
               for Confidential Treatment], Vendor will provision end-to-end
               bandwidth such that average bandwidth available per user at peak
               will be [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment].

          (b)  The Dial-Up Access Services shall fully support and be in
               conformance with Customer's access methods, access technology,
               hub architecture, and other access methods that may become
               available to Customer from time to time. Access methods shall
               include:

               (i)  [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment];

               (ii) [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment];

              (iii) [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment];

               (iv) [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment];

               (v)  [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment];

               (vi) [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment];

              (vii) [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment];

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                       CONFIDENTIAL TREATMENT REQUESTED

             (viii) [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment] (including those provided by
                    Customer and any other Customer-offered service) as
                    requested by Customer at [*Material Omitted and Separately
                    Filed Under an Application for Confidential Treatment],
                    provided that the cost of [*Material Omitted and Separately
                    Filed Under an Application for Confidential Treatment],
                    subject to prior agreement by Vendor and Customer on how
                    routing is implemented. Interconnect costs of service to
                    [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment] will be treated as an [*Material
                    Omitted and Separately Filed Under an Application for
                    Confidential Treatment] until the earlier of [*Material
                    Omitted and Separately Filed Under an Application for
                    Confidential Treatment], and [*Material Omitted and
                    Separately Filed Under an Application for Confidential
                    Treatment] the date on which [*Material Omitted and
                    Separately Filed Under an Application for Confidential
                    Treatment]; provided however that any such [*Material
                    Omitted and Separately Filed Under an Application for
                    Confidential Treatment] charged to Customer by Vendor will
                    be reduced on a monthly basis by an amount equal to the
                    [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment];

               (ix) [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment], provided that the cost of
                    user's [*Material Omitted and Separately Filed Under an
                    Application for Confidential Treatment], subject to prior
                    agreement by Vendor and Customer on how routing is
                    implemented; and

               (x)  [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment], provided that the cost
                    [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment] does not exceed the cost of
                    [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment], subject to prior agreement by
                    Vendor and Customer on how routing is implemented.

          (c)  Vendor, in its network design and topology, shall comply with
               IETF approved and adopted standards applicable to the access
               methods described in Subsection (b) of this Section.

     9.2. Acceptance Criteria.
          -------------------

          The following Acceptance Criteria shall apply to Dedicated Dial-Up
          Access Ports:

          Newly activated Dedicated Dial-Up Access Ports will fail Dial-Up
          Acceptance Testing if any of the following thresholds is met:

          (a)  greater than [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment];

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                       CONFIDENTIAL TREATMENT REQUESTED

          (b)  greater than [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment] (such data will be
               provided by Vendor for the [*Material Omitted and Separately
               Filed Under an Application for Confidential Treatment];

          (c)  greater than [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment] which successfully
               [*Material Omitted and Separately Filed Under an Application for
               Confidential Treatment] to the [*Material Omitted and Separately
               Filed Under an Application for Confidential Treatment] to connect
               [*Material Omitted and Separately Filed Under an Application for
               Confidential Treatment]

          provided, however, that notwithstanding the foregoing, [*Material
          Omitted and Separately Filed Under an Application for Confidential
          Treatment]. The Acceptance Test Period will be contingent upon
          Customer's receiving the[*Material Omitted and Separately Filed Under
          an Application for Confidential Treatment] beginning with a [*Material
          Omitted and Separately Filed Under an Application for Confidential
          Treatment]. Customer will not [*Material Omitted and Separately Filed
          Under an Application for Confidential Treatment].

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                       CONFIDENTIAL TREATMENT REQUESTED

                                   EXHIBIT B-1

                           Dial-Up Purchase Commitment

1.   CONFIDENTIALITY

     This Exhibit specifies the Monthly Targets for Customer's Dial-Up Purchase
     Commitments pursuant to Schedule B. The Parties specifically acknowledge
     that the purchase commitment information contained herein is highly
     confidential and that its disclosure to the public or third parties could
     cause significant harm to either Customer or Vendor or both.

2.   DIAL-UP PURCHASE COMMITMENT

          (a)  The Monthly Target for the following months shall be as follows:

          (b)  For [*Material Omitted and Separately Filed Under an Application
               for Confidential Treatment] Monthly Target shall be an amount
               determined [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment];

          (c)  For [*Material Omitted and Separately Filed Under an Application
               for Confidential Treatment] Target shall be an amount determined
               [*Material Omitted and Separately Filed Under an Application for
               Confidential Treatment] that is no less than [*Material Omitted
               and Separately Filed Under an Application for Confidential
               Treatment] but no more than [*Material Omitted and Separately
               Filed Under an Application for Confidential Treatment];

          (d)  For [*Material Omitted and Separately Filed Under an Application
               for Confidential Treatment] the Monthly Target shall be an amount
               determined [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment] that is no less than
               [*Material Omitted and Separately Filed Under an Application for
               Confidential Treatment] but no more than [*Material Omitted and
               Separately Filed Under an Application for Confidential
               Treatment]; and

          (e)  For [*Material Omitted and Separately Filed Under an Application
               for Confidential Treatment] the Monthly Target shall [*Material
               Omitted and Separately Filed Under an Application for
               Confidential Treatment] (except as otherwise mutually agreed upon
               by the Parties).

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                       CONFIDENTIAL TREATMENT REQUESTED

                                   EXHIBIT B-2

                       Prices for Dial-Up Access Services

1.   CONFIDENTIALITY

     This Exhibit specifies the prices for Dial-Up Access Services provided
     pursuant to the Master Agreement and Schedule B. The Parties specifically
     acknowledge that the pricing information contained herein is highly
     confidential and that its disclosure to the public or third parties could
     cause significant harm to either Customer or Vendor or both.

2.   MARKET PRICE FOR EXISTING DIAL-UP ACCESS PORTS

     The Monthly EDAP Charge shall be set at [*Material Omitted and Separately
     Filed Under an Application for Confidential Treatment], which price,
     effective from [*Material Omitted and Separately Filed Under an Application
     for Confidential Treatment] through [*Material Omitted and Separately Filed
     Under an Application for Confidential Treatment], shall be [*Material
     Omitted and Separately Filed Under an Application for Confidential
     Treatment] dollars ($[*Material Omitted and Separately Filed Under an
     Application for Confidential Treatment]). [*Material Omitted and Separately
     Filed Under an Application for Confidential Treatment] shall be further
     [*Material Omitted and Separately Filed Under an Application for
     Confidential Treatment] according to the following schedule:

          (a)  From [*Material Omitted and Separately Filed Under an Application
               for Confidential Treatment] through [*Material Omitted and
               Separately Filed Under an Application for Confidential Treatment]
               the Monthly EDAP Charge shall be [*Material Omitted and
               Separately Filed Under an Application for Confidential Treatment]
               dollars [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment];

          (b)  From [*Material Omitted and Separately Filed Under an Application
               for Confidential Treatment] through [*Material Omitted and
               Separately Filed Under an Application for Confidential Treatment]
               the Monthly EDAP Charge shall be [*Material Omitted and
               Separately Filed Under an Application for Confidential Treatment]
               dollars [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment];

          (c)  From [*Material Omitted and Separately Filed Under an Application
               for Confidential Treatment] through the remainder of [*Material
               Omitted and Separately Filed Under an Application for
               Confidential Treatment] the Monthly EDAP Charge shall be
               [*Material Omitted and Separately Filed Under an Application for
               Confidential Treatment] dollars [*Material Omitted and Separately
               Filed Under an Application for Confidential Treatment].

     Notwithstanding the foregoing, the Monthly EDAP Charge [*Material Omitted
     and Separately Filed Under an Application for Confidential Treatment] may
     be [*Material Omitted and Separately Filed Under an Application for
     Confidential Treatment (A) [*Material Omitted and Separately Filed Under an
     Application for Confidential Treatment] pursuant to Section [*Material
     Omitted and Separately Filed Under an Application for Confidential
     Treatment] to the [*Material Omitted and Separately Filed Under an
     Application for Confidential Treatment] dollars [*Material Omitted and
     Separately Filed Under an Application for Confidential Treatment] (B) the
     applicable amount [*Material Omitted and Separately Filed Under an
     Application for Confidential Treatment] (2) otherwise pursuant to Article
     [*Material Omitted and Separately Filed Under an Application for
     Confidential Treatment].

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                       CONFIDENTIAL TREATMENT REQUESTED

3.   MARKET PRICE FOR DIAL-UP ACCESS PORTS

     The Monthly DAP Charge shall be set at the [*Material Omitted and
     Separately Filed Under an Application for Confidential Treatment], which
     price, [*Material Omitted and Separately Filed Under an Application for
     Confidential Treatment] from the [*Material Omitted and Separately Filed
     Under an Application for Confidential Treatment] through [*Material Omitted
     and Separately Filed Under an Application for Confidential Treatment],
     shall be [*Material Omitted and Separately Filed Under an Application for
     Confidential Treatment]. From [*Material Omitted and Separately Filed Under
     an Application for Confidential Treatment] through [*Material Omitted and
     Separately Filed Under an Application for Confidential Treatment]
     Notwithstanding the foregoing, the Monthly DAP Charge may be [*Material
     Omitted and Separately Filed Under an Application for Confidential
     Treatment] (1) pursuant to Section [*Material Omitted and Separately Filed
     Under an Application for Confidential Treatment] to the [*Material Omitted
     and Separately Filed Under an Application for Confidential Treatment] of
     (A) the applicable amount [*Material Omitted and Separately Filed Under an
     Application for Confidential Treatment] (B) [*Material Omitted and
     Separately Filed Under an Application for Confidential Treatment] or (2)
     otherwise pursuant to Article [*Material Omitted and Separately Filed Under
     an Application for Confidential Treatment].

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Schedule B                  Schedule B-2 - Page 2
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

                                   SCHEDULE C

      Broadband Backhaul Services, Service Levels, Pricing and Other Terms

1.   TERM

     The term of this Schedule C shall begin on the Effective Date and shall
     expire on December 31, 2004, unless terminated earlier in accordance with
     the Agreement; provided that Customer may, with the consent of Vendor,
     renew such term for three (3) additional one (1) year periods by giving
     Vendor at least thirty (30) days notice prior to the end of the applicable
     term or renewal period (such period, as terminated earlier or so extended,
     the "Broadband Term").

2.   CONSTRUCTION OF AGREEMENT WITH RESPECT TO NON-XDSL BROADBAND SERVICES

          (a)  Although this Agreement governs Broadband Backhaul Services for
               both xDSL and other broadband services, the Parties acknowledge
               that the particular rights, duties and obligations set forth
               herein, including service levels, delivery of service, failure to
               meet service levels, failure to deliver service, the Broadband
               Specifications, and other provisions, and the impact of such
               matters on related purchase commitments as well as other rights
               and remedies, have been worked out in the particular context of
               xDSL broadband services. Therefore, although the rights, duties
               and obligations herein apply to broadband services other than
               xDSL, the Parties agree to negotiate in good faith how certain
               provisions herein that are stated in terms particularly relevant
               to xDSL broadband services will apply in the context of broadband
               services other than xDSL.

          (b)  The Parties acknowledge and agree that with respect to certain
               Broadband Backhaul Services used to provide any non-xDSL or
               non-cable broadband service with [*Material Omitted and
               Separately Filed Under an Application for Confidential Treatment
               utilized for an xDSL or cable broadband service and for which
               delivery of such non-xDSL or non-cable service is not based upon
               the [*Material Omitted and Separately Filed Under an Application
               for Confidential Treatment], the Other Broadband Purchase
               Commitment and the pricing set forth in Exhibit C-2 of this
               Schedule C shall each be adjusted, as mutually agreed, to reflect
               an appropriate methodology; provided, however, that (i) with
               respect to the adjustment to the Other Broadband Purchase
               Commitment, such adjustment shall only be made to reflect such
               appropriate methodology, and the commitment [*Material Omitted
               and Separately Filed Under an Application for Confidential
               Treatment] as such [*Material Omitted and Separately Filed Under
               an Application for Confidential Treatment] as set forth in
               [*Material Omitted and Separately Filed Under an Application for
               Confidential Treatment] and may be adjusted pursuant to the terms
               of this Schedule C shall not be increased or reduced but shall be
               applied to the adjusted methodology, and (ii) Section 7.2 of this
               Schedule C shall continue to apply to the Other Broadband
               Purchase Commitment and pricing, as adjusted.

--------------------------------------------------------------------------------
Network Services Agreement   America Online, Inc. / BBN Corporation CONFIDENTIAL
Schedule B                  Schedule C - Page 1
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

3.   ORDERING AND ACCEPTANCE CRITERIA

     3.1. Ordering.
          --------

          (a)  Forecasts of Customer's Expected Broadband Backhaul Services
               ------------------------------------------------------------
               Needs in New LATAs. At the start of every calendar quarter,
               ------------------
               Customer will provide Vendor with a non-binding forecast that
               sets forth those New LATAs in which Customer expects it will need
               Broadband Backhaul Services over the next three (3) calendar
               quarters.

          (b)  Ordering Broadband Backhaul Services in Existing LATAs. The
               ------------------------------------------------------
               Parties shall mutually agree upon the standards and procedures
               for ordering Broadband Backhaul Services in Existing LATAs
               (including (i) scheduling procedures, timelines, performance
               metrics and remedies, (ii) the ongoing sharing of information
               back and forth between the Parties as appropriate or necessary to
               maximize efficiencies and minimize provisioning turnarounds times
               and (iii) such other issues as the Parties may mutually agree).
               The Parties specifically agree that a principal objective of the
               ordering process shall be to meet in a timely manner Customer's
               Subscriber Line demand. The Parties shall mutually agree upon
               changes from time to time to the ordering process to facilitate
               the provision of Broadband Backhaul Services to Customer.

          (c)  Launch of Broadband Backhaul Services in New LATAs. Customer
               --------------------------------------------------
               shall direct the launch of New LATAs consistent with the timing
               of the local access provider and Customer becoming ready to
               provide xDSL service in that LATA. Any time Customer requests
               that Vendor provision Broadband Backhaul Services in a New LATA,
               Customer will provide Vendor with notice (each, a "New LATA
               Notice") specifying such LATA (as applicable), the initial
               capacity to be provided in such LATA, and the date Customer
               anticipates it will begin utilizing such Broadband Backhaul
               Services in such LATA. In the event that Customer notifies Vendor
               of a requested change in the specifics of a New LATA Notice
               provided to Vendor, the Parties will mutually agree upon the
               extent, if any, that (i) such requested change will affect the
               time period specified in Section 3.2(a) of this Schedule C, and
               (ii) Customer will pay Vendor Out-of-Pocket Expenses incurred by
               Vendor as a result of such requested change.

          (d)  Geographic Distribution. Notwithstanding the foregoing:
               -----------------------

               (i)  the distribution of Vendor Broadband Subscriber Lines
                    providing xDSL broadband services will be approximately
                    proportional to the nationwide distribution of all of the
                    Aggregate DSL Subscriber Lines; and

               (ii) the distribution of Vendor Broadband Subscriber Lines
                    providing broadband services other than xDSL will be
                    approximately proportional to the nationwide distribution of
                    all of the Aggregate Other Subscriber Lines.

               For the purposes of this Subsection (d), "distribution" means the
               distribution of the corresponding Vendor Broadband Subscriber
               Lines across rural versus urban

--------------------------------------------------------------------------------
Network Services Agreement   America Online, Inc. / BBN Corporation CONFIDENTIAL
Schedule B                  Schedule C - Page 2
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

               areas, across the contiguous states of the United States, and
               between Covered Subscriber Lines and non-Covered Subscriber
               Lines. In the event that Vendor believes Customer has provided
               Vendor with tasking that is inconsistent with this Subsection
               (d), the Parties will mutually agree on an equitable resolution
               consistent with the intent of this Section. In January and July
               of each calendar year, Customer shall provide Vendor with
               relevant information regarding the distribution of Aggregate
               Subscriber Lines.

          (e)  Reports on Subscriber Line Activations. At least once per week
               --------------------------------------
               Customer will provide Vendor a report on the number of Vendor
               Broadband Subscriber Lines activated from each service provider
               by LATA for the previous seven (7) day period.

     3.2. Delivery.
          --------

          (a)  General. Vendor shall provision Broadband Backhaul Services for
               -------
               each Existing LATA in accordance with the standards and
               procedures described in Section 1(b) of this Schedule C. Vendor
               shall use demonstrable good faith diligent efforts to provision
               Broadband Backhaul Services for each New LATA within [*Material
               Omitted and Separately Filed Under an Application for
               Confidential Treatment] days of its receipt of a New LATA Notice
               corresponding to such New LATA.

          (b)  Reductions in Broadband Purchase Commitments for Delivery
               ---------------------------------------------------------
               Failures.
               --------

               (i)  Definitions.

                    (1)  "Failure Percentage" means, as of a Measurement Date,
                         the percentage resulting from (i) [*Material Omitted
                         and Separately Filed Under an Application for
                         Confidential Treatment] that as of such Measurement
                         Date, Vendor has failed to [*Material Omitted and
                         Separately Filed Under an Application for Confidential
                         Treatment] pursuant to Section 1.1(a) of this Schedule
                         within the [*Material Omitted and Separately Filed
                         Under an Application for Confidential Treatment]
                         applicable to each such [*Material Omitted and
                         Separately Filed Under an Application for Confidential
                         Treatment] divided by the (ii) the sum of (A)
                         [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment] pursuant to
                         Section 1.1(a) of this Schedule as of such [*Material
                         Omitted and Separately Filed Under an Application for
                         Confidential Treatment] plus (B) [*Material Omitted and
                         Separately Filed Under an Application for Confidential
                         Treatment] to be [*Material Omitted and Separately
                         Filed Under an Application for Confidential Treatment]
                         of this [*Material Omitted and Separately Filed Under
                         an Application for Confidential Treatment] and for
                         which the applicable [*Material Omitted


--------------------------------------------------------------------------------
Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Schedule C                   Schedule C - Page 3
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

                          and Separately Filed Under an Application for
                          Confidential Treatment].

                     (2)  "Failure Threshold Percentages" means the percentage
                          set forth in the following table:
<TABLE>
                          <S>                                      <C>
                          ---------------------------------------- -------------------------------
                             [*Material Omitted and Separately      Failure Threshold Percentage
                              Filed Under an Application for
                                  Confidential Treatment]
                          ---------------------------------------- -------------------------------
                                                                       [*Material Omitted and
                                                                     Separately Filed Under an
                                                                    Application for Confidential
                                                                             Treatment]
                          ---------------------------------------- -------------------------------

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

                          ---------------------------------------- -------------------------------
</TABLE>

                     (3)  "Threshold Difference" as of a Measurement Date equals
                          the Failure Percentage minus the Failure Threshold
                          Percentage, except that the Threshold Difference can
                          never be less than zero.

               (ii)  Reduction Calculation. Reduction of the Broadband Purchase
                     Commitments shall be as set forth in Section 3.1 of Exhibit
                     C-1 of this Schedule C.

               (iii) Examples. Examples of reductions in the Broadband Purchase
                     Commitments for delivery failures are set forth in Section
                     3.2 of Exhibit C-1 of this Schedule C.

          (c)  If Vendor fails to (i) provision Broadband Backhaul Services for
               a New LATA within [*Material Omitted and Separately Filed Under
               an Application for Confidential Treatment] days of its receipt of
               a New LATA Notice corresponding to such New LATA, and (ii) use
               demonstrable good faith diligent efforts to provision Broadband
               Backhaul Services for such New LATA, then Customer may terminate
               its obligations with respect to the Broadband Backhaul Purchase
               Commitments. Upon Customer's request, Vendor shall provide
               Customer with information and supporting documentation which
               demonstrates Vendor's good faith diligent efforts to provision
               such services for the applicable New LATA within [*Material
               Omitted and Separately Filed Under an Application for
               Confidential Treatment] days of receipt of the corresponding New
               LATA Notice (e.g., documents showing Vendor's ordering of
               circuits in such New LATA).

     3.3. Acceptance Criteria.
          -------------------

          (a)  Prior to notifying Customer that Broadband Backhaul Services are
               available in any geographic area, Vendor will conduct testing
               utilizing a series of [*Material

--------------------------------------------------------------------------------
Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Schedule C                   Schedule C - Page 4
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

               Omitted and Separately Filed Under an Application for
               Confidential Treatment] tests which validate [*Material Omitted
               and Separately Filed Under an Application for Confidential
               Treatment] connectivity from the service provider's [*Material
               Omitted and Separately Filed Under an Application for
               Confidential Treatment] and (ii) a series of [*Material Omitted
               and Separately Filed Under an Application for Confidential
               Treatment] that validate connectivity from the [*Material Omitted
               and Separately Filed Under an Application for Confidential
               Treatment]. Once connectivity described in Subsections (i) and
               (ii) of this Subsection (a) [*Material Omitted and Separately
               Filed Under an Application for Confidential Treatment], Vendor
               will provide Customer with notice that the Broadband Backhaul
               Services are ready for use by Customer.

          (b)  The Broadband Backhaul Services will be deemed accepted for a
               specific LATA or other relevant geographic area when the
               [*Material Omitted and Separately Filed Under an Application for
               Confidential Treatment] in accordance with the [*Material Omitted
               and Separately Filed Under an Application for Confidential
               Treatment]. Vendor will reasonably cooperate with acceptance
               testing by Customer. Customer will begin providing the Broadband
               Backhaul Services to its end-customers as soon as reasonably
               practicable after Customer completes its acceptance testing.

     3.4. Broadband Backhaul Purchase Commitments.
          ---------------------------------------

          Customer agrees to purchase Broadband Backhaul Services according to
          the purchase commitments set forth in Exhibit C-1 of this Schedule C.

4.   TERMINATION

     4.1. Vendor Termination.
          ------------------

          (a)  In the event that the aggregate number of Vendor Broadband
               Subscriber Lines:

          (b)  is less than [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment] as of [*Material Omitted
               and Separately Filed Under an Application for Confidential
               Treatment];

          (c)  is less than [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment] as of [*Material Omitted
               and Separately Filed Under an Application for Confidential
               Treatment];

          (d)  is less than [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment] as of [*Material Omitted
               and Separately Filed Under an Application for Confidential
               Treatment]; or

          (e)  is less than [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment] as of [*Material Omitted
               and Separately Filed Under an Application for Confidential
               Treatment],

--------------------------------------------------------------------------------
Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Schedule C                   Schedule C - Page 5
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

               Vendor may within thirty (30) calendar days of the applicable
               calendar day set forth above for the corresponding Vendor
               Broadband Subscriber Line threshold provide Customer with notice
               of termination of this Schedule C. Such termination shall become
               effective on the date specified in such notice (which date shall
               be no earlier than one hundred fifty (150) calendar days
               following the date of such notice and no later than the end of
               the Broadband Term) unless within thirty (30) calendar days of
               the date of such notice, the number of Vendor Broadband
               Subscriber Lines is equal to or greater than such corresponding
               threshold . In the event of such termination, (i) Customer shall
               have no liability to Vendor for failure to achieve the Broadband
               Purchase Commitments, and (ii) except with respect to the
               provision of Transition Assistance pursuant to this Section,
               Vendor shall have no liability to Customer. Upon such
               termination, Vendor shall provide Transition Assistance in
               accordance with Section 13.4 of the Master Agreement. Nothing in
               this Section shall be deemed to affect the obligations of
               Customer with respect to the Broadband Purchase Commitments so
               long as Vendor has not provided Customer with a notice of
               termination pursuant to this Section.

     4.2. Termination of xDSL Field Trials.
          --------------------------------

          The xDSL field trials described in the Original Agreement for (a)
          Phoenix, Arizona, (b) San Francisco, California, (c) Birmingham,
          Alabama, (d) northern Virginia, and (e) Redmond, Washington shall be
          terminated as of January 31, 2000; provided, however, that any of such
          field trials will be continued upon the request of Customer. In the
          event of any such continuation, Customer shall reimburse Vendor for
          Out-of-Pocket Expenses incurred by Vendor as a result of such
          continuation.

5.   DESCRIPTION OF SERVICES

     Vendor shall provide nationwide (i.e., within the forty-eight contiguous
     states of the United States plus Hawaii) broadband (including xDSL, cable,
     wireless and satellite technologies) backbone integration services
     combining inter- and intra-LATA interconnects, aggregation equipment,
     co-location, backbone transport and network management control. Such
     services shall include the provision of the services described in this
     Article 5.

     5.1. Summary and Implementation Plan.
          -------------------------------

          Vendor will provide program management, network engineering,
          deployment, and operations support for broadband network services
          integration for Customer.

          (a)  Program Management.
               ------------------

               Vendor will assign a Program Management Team that will be
               responsible for the management of the provision of Broadband
               Backhaul Services as a whole. The Program Management Team will
               serve as Vendor's primary point of contact for Customer. Such
               team will coordinate the activity of all functional groups within
               Vendor and will be responsible for project and financial
               management of the Broadband Backhaul Services.

          (b)  Network Engineering.
               -------------------

--------------------------------------------------------------------------------
Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Schedule C                   Schedule C - Page 6
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

               Vendor will provide network engineering expertise to address
               technical issues that arise during the deployment of the
               Broadband Backhaul Services and operation of the Vendor Network.
               Vendor will be responsible for performing network design;
               planning network expansion; documenting technical procedures;
               resolving problems escalated by the NOC; addressing architecture,
               implementation and performance issues; providing cost reduction
               recommendations; and performing continuous process improvement.

          (c)  Deployment.
               ----------

               Vendor will assign a Deployment Team that will consist of field
               engineers and technicians. Such team will be responsible for
               planning and implementing logistics, procuring equipment and
               circuits, coordinating with network service providers' access
               points, staging, integration, testing, shipping, and installing
               equipment.

          (d)  Operations.
               ----------

               Vendor's NOCs will handle the operation and maintenance of the
               Vendor Network. The NOC shall be connected to Customer's central
               facilities using a direct leased line to Customer's operations
               center.

     5.2. Design and Topology of the Vendor Network.
          ------------------------------------------

          Vendor will utilize its Global Network Infrastructure (GNI) backbone
          for transport of broadband traffic to Customer data centers; provided
          that in order to provide last mile diversity, at Customer's request,
          for up to [*Material Omitted and Separately Filed Under an Application
          for Confidential Treatment] percent of the GNI last mile capacity to
          Customer's facilities, Customer and Vendor agree to exchange local
          facilities, at no cost to either Party, for equivalent bandwidth
          exchanged. The Parties agree to establish a mutually acceptable
          bandwidth-exchanging and circuit-management process, including with
          respect to co-location space, facility access, and helping hands where
          both Parties have local facilities in each geography.

          (a)  Equipment Configuration.
               ------------------------

               Vendor acknowledges that quality of the Broadband Backhaul
               Services is critical to the satisfaction of the users of
               Customer's services and will work to minimize any quality issues
               associated with the rapid implementation of new service
               technologies (other than to the extent that such quality issues
               are caused by new service technologies directed by Customer).
               Vendor will utilize a complement of equipment at broadband POPs.
               Customer will reasonably cooperate with Vendor in the testing and
               implementation of any alternative equipment at the broadband POPs
               that Vendor desires to implement. A sample configuration of
               equipment is described below.

               [*Material Omitted and Separately Filed Under an Application for
               Confidential Treatment]. Ancillary equipment will be provided in
               each POP to

--------------------------------------------------------------------------------
Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Schedule C                   Schedule C - Page 7
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

               support configuration and management functions. [*Material
               Omitted and Separately Filed Under an Application for
               Confidential Treatment].

          (b)  Points of Presence (POPs).
               --------------------------

               Vendor currently locates broadband POPs in GTE Internetworking
               GNI facilities. Such GNI facilities provide space for 19" racks,
               associated power, cabling and environmental conditioning.

          (c)  Network Topology.
               -----------------

               (i)   The Vendor Network utilized to provide Broadband Backhaul
                     Services is currently structured as a [*Material Omitted
                     and Separately Filed Under an Application for Confidential
                     Treatment]. Broadband POPs will be located at [*Material
                     Omitted and Separately Filed Under an Application for
                     Confidential Treatment].

               (ii)  Traffic from [*Material Omitted and Separately Filed Under
                     an Application for Confidential Treatment].

               (iii) Vendor's NOCs will maintain [*Material Omitted and
                     Separately Filed Under an Application for Confidential
                     Treatment].

               (iv)  [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] Under this Schedule
                     C, Vendor is not currently responsible for [*Material
                     Omitted and Separately Filed Under an Application for
                     Confidential Treatment].

          (d)  Vendor agrees that any changes to the Broadband Backhaul Services
               or to the Vendor Network used to provide the Broadband Backhaul
               Services will be fully functional with services provided by
               Customer without modification of, or addition to, client or host
               software used to provide services provided by Customer that
               utilize the Broadband Backhaul Services.

          (e)  In the event that Customer requests a change to the hub
               architecture, or network bandwidth from that which is described
               in this Schedule C (other than a request for increased throughput
               priced pursuant to Section 8(a) of this Schedule C), Vendor will
               provide Customer with Vendor's proposed increase, if any, to the
               prices set forth in this Schedule C. To the extent that Customer
               accepts such proposal, Vendor shall provide the Broadband
               Backhaul Services in accordance with the requested change and
               Vendor's proposal to the extent accepted by Customer.

     5.3. Deployment.
          ----------

          (a)  Vendor will take the following steps in preparation for deploying
               equipment used to provide the Broadband Backhaul Services as may
               be appropriate:

               (i)  Coordinating provisioning schedules with Customer
                    representatives;

--------------------------------------------------------------------------------
Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Schedule C                   Schedule C - Page 8
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

               (ii)  Negotiating with telecommunications vendors for procurement
                     and installation of appropriate access and network
                     connections;

               (iii) Negotiating with telecommunications vendors for
                     reservations of floor space for installation of such
                     equipment;

               (iv)  Coordinating with site organizations for housing such
                     equipment and spares, and for developing agreements to
                     assist with troubleshooting activities as directed by the
                     NOC;

               (v)   Procuring equipment;

               (vi)  Receiving, storing, and tracking equipment; and

               (vii) Scheduling installations.

          (b)  Preparation.
               ------------

               (i)   Site Survey. Vendor will conduct site surveys in order to
                     identify site preparation which must be completed prior to
                     installation, special equipment requirements, interface
                     requirements, and the physical placement of equipment.

               (ii)  Inventory of Materials. Vendor will prepare inventories of
                     materials prior to installation of equipment at each site
                     identifying all components by common nomenclature, part
                     number, quantity required, and size or length, as
                     applicable.

               (iii) Equipment Staging. Vendor will stage and test all equipment
                     in a central location and then ship such equipment to the
                     appropriate site. Vendor will assemble, tag and stage for
                     shipping all equipment required for installation at the
                     site. Staging consists of assembling and testing pre-
                     configured interfaces and other components at the Vendor
                     facility.

               (iv)  Shipping. Vendor will arrange for shipping of the staged
                     equipment to the installation locations and ensure that all
                     equipment arrives at the installation sites prior to the
                     scheduled site visit date. Equipment scheduled for
                     installation by Vendor will be held at the site until the
                     Vendor installation team arrives to uncrate and install it.

               (v)   Installation. Vendor will install equipment onsite and
                     verify functionality according to specifications.
                     Installation includes the following activities:

                     (1)  Briefing site personnel;

                     (2)  Taking inventory of equipment and resolving
                          discrepancies;

                     (3)  Relocating equipment to footprint;

--------------------------------------------------------------------------------
Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Schedule C                   Schedule C - Page 9
<PAGE>

                    CONFIDENTIAL TREATMENT REQUESTED

                    (4)  Bolting cabinets together (if applicable);

                    (5)  Installing intra-cabinet and inter-cabinet cables;

                    (6)  Connecting power and station ground;

                    (7)  Dressing and labeling cables, fantails, ports, and
                         mod-taps; and

                    (8)  Connecting to the network and ensuring operability.

          (c)  Maintenance.
               -----------

               (i)   Vendor will perform maintenance of equipment used to
                     provide the Broadband Backhaul Services based on input from
                     the monitoring systems and Customer. Vendor will handle
                     most [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] over the [*Material
                     Omitted and Separately Filed Under an Application for
                     Confidential Treatment] at the [*Material Omitted and
                     Separately Filed Under an Application for Confidential
                     Treatment] at the [*Material Omitted and Separately Filed
                     Under an Application for Confidential Treatment]
                     establishing working agreements with the [*Material Omitted
                     and Separately Filed Under an Application for Confidential
                     Treatment] and other [*Material Omitted and Separately
                     Filed Under an Application for Confidential Treatment] and
                     by providing written procedures.

               (ii)  Vendor will cooperate with Customer with respect to new
                     versions of software used to provide those services
                     provided by Customer that utilize the Broadband Backhaul
                     Services.

               (iii) Vendor shall reasonably coordinate with Customer regarding
                     any maintenance activity.

          (d)  Quality Control.
               ---------------

               Vendor will maintain a Quality Control Program to ensure all
               reasonable commercial standards applicable to Broadband Backhaul
               Services are adhered to.

     5.4. Management of Circuits.
          ----------------------

          Vendor will manage the [*Material Omitted and Separately Filed Under
          an Application for Confidential Treatment] necessary to meet
          [*Material Omitted and Separately Filed Under an Application for
          Confidential Treatment] outlined in this Schedule C. Vendor will
          utilize existing procedures and systems for [*Material Omitted and
          Separately Filed Under an Application for Confidential Treatment] as
          such may change from time to time. As part of the installation
          activities outlined above, Vendor will [*Material Omitted and
          Separately Filed Under an Application for Confidential Treatment].

--------------------------------------------------------------------------------
Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Schedule C                   Schedule C - Page 10
<PAGE>

                     CONFIDENTIAL TREATMENT REQUESTED

     5.5. Operations.
          ----------

          Vendor will provision, staff and operate a NOC (currently in Columbia,
          Maryland) with dedicated support for Customer and a backup NOC at a
          separate location (such backup NOC is currently located in Chantilly,
          Virginia). Responsibilities of Vendor's operations support team
          include the following:

          (a)  Operation of the NOC and co-located systems with trained and
               qualified personnel on a continuous 24-hours-per-day,
               seven-days-per-week basis.

          (b)  Operation of all NOC equipment, monitoring, and fault isolation
               functions.

          (c)  Utilization of network management capabilities and Vendor
               diagnostic software resident in the NOC for:

               (i)   Monitoring [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment].

               (ii)  Measuring [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] .

               (iii) Monitoring and recording [*Material Omitted and Separately
                     Filed Under an Application for Confidential Treatment].

               (iv)  Tracking the disposition of [*Material Omitted and
                     Separately Filed Under an Application for Confidential
                     Treatment].

          (d)  Coordination and management of field technicians for maintenance
               activities associated with the Vendor Network.

          (e)  Coordination and reporting of all support activities using a
               commercial trouble reporting system [*Material Omitted and
               Separately Filed Under an Application for Confidential
               Treatment].

          (f)  Support of short-term and long-term problem identification,
               analysis, and resolution.

          (g)  Identification and tracking of all software changes deployed in
               the Vendor Network and NOC platforms.

          (h)  Support for the deployment of new software and hardware (as
               coordinated with Customer).

          (i)  Provision of operational support to the Vendor Network for
               testing in association with provisioning activities.

          (j)  Maintenance of NOC maps.

--------------------------------------------------------------------------------
Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Schedule C                   Schedule C - Page 11
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

          (k)  Coordination of Vendor Network change management activities and
               maintenance of authorized outage lists.

          (l)  Support of Customer in security matters in accordance with
               customary industry practices.

          (m)  Delivery of reports to pre-designated Customer representatives
               addressing the following:

               (i)   [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment];

               (ii)  [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment];

               (iii) [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment];

               (iv)  [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment];

               (v)   [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment];

               (vi)  [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment];

               (vii) Upon Customer's request, Vendor shall provide Customer with
                     [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] that are utilized
                     to provide Broadband Backhaul Services under this Schedule
                     C. In addition, for [*Material Omitted and Separately Filed
                     Under an Application for Confidential Treatment] that are
                     utilized to provide Broadband Backhaul Services under this
                     Schedule C, Vendor shall provide to Customer a daily report
                     covering the [*Material Omitted and Separately Filed Under
                     an Application for Confidential Treatment] as such data is
                     collected by Vendor. In the event of a Vendor Network
                     outage, Vendor will work cooperatively with Customer to
                     share additional [*Material Omitted and Separately Filed
                     Under an Application for Confidential Treatment] data which
                     may be pertinent to the resolution of any such outage, and,
                     upon Customer's reasonable request, Vendor will provide
                     [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment]to assist in the
                     outage resolution. In the event of a Vendor Network
                     performance degradation, Vendor will work cooperatively
                     with Customer to share additional [*Material Omitted and
                     Separately Filed Under an Application for Confidential
                     Treatment] data which may be pertinent to the resolution of
                     any such degradation, and, upon Customer's reasonable
                     request, Vendor will provide [*Material Omitted and
                     Separately Filed Under an

--------------------------------------------------------------------------------
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                       CONFIDENTIAL TREATMENT REQUESTED

                      Application for Confidential Treatment] to assist in the
                      problem resolution. All access by Customer will be
                      coordinated with Vendor in advance, and the polling
                      frequency for any device will be as the parties mutually
                      agree in advance for the [*Material Omitted and Separately
                      Filed Under an Application for Confidential Treatment];

               (viii) [*Material Omitted and Separately Filed Under an
                      Application for Confidential Treatment], including the
                      following:

                      (1)  [*Material Omitted and Separately Filed Under an
                           Application for Confidential Treatment];

                      (2)  [*Material Omitted and Separately Filed Under an
                           Application for Confidential Treatment];

                      (3)  [*Material Omitted and Separately Filed Under an
                           Application for Confidential Treatment];

                      (4)  [*Material Omitted and Separately Filed Under an
                           Application for Confidential Treatment];

                      (5)  [*Material Omitted and Separately Filed Under an
                           Application for Confidential Treatment];

                      (6)  [*Material Omitted and Separately Filed Under an
                           Application for Confidential Treatment];

                      (7)  [*Material Omitted and Separately Filed Under an
                           Application for Confidential Treatment];

                      (8)  [*Material Omitted and Separately Filed Under an
                           Application for Confidential Treatment];

                      (9)  [*Material Omitted and Separately Filed Under an
                           Application for Confidential Treatment];

                      (10) [*Material Omitted and Separately Filed Under an
                           Application for Confidential Treatment];

                      (11) [*Material Omitted and Separately Filed Under an
                           Application for Confidential Treatment]

                      (12) [*Material Omitted and Separately Filed Under an
                           Application for Confidential Treatment


               provided that Vendor shall provide Customer with weekly reports
               on [*Material Omitted and Separately Filed Under an Application
               for Confidential Treatment] sufficient to enable customer to
               determine [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment] in

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Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Schedule C                   Schedule C - Page 13
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

               accordance with Section 8(a) of this Schedule C, and, as soon as
               technically feasible, Vendor shall provide such reports to
               Customer on a daily basis. Customer may periodically request
               additional reports that assist in improving network quality and
               analyzing [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment]. Vendor will provide
               these additional reports, or the raw data, subject to technical
               reasonableness.

     5.6. Aggregation Router Equipment.
          ----------------------------

          (a)  Aggregation router equipment used to provide the Broadband
               Backhaul Services shall be [*Material Omitted and Separately
               Filed Under an Application for Confidential Treatment] of
               Broadband Backhaul Services to Customer under this Agreement and
               shall not be [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment].

          (b)  Customer may specify the operating system features to be utilized
               for aggregation router equipment selected by Vendor and used to
               provide the Broadband Backhaul Services.

     5.7. Excluded Functions.
          ------------------

          Vendor shall not be responsible for providing the following with
          respect to the Broadband Backhaul Services:

          (a)  [*Material Omitted and Separately Filed Under an Application for
               Confidential Treatment];

          (b)  [*Material Omitted and Separately Filed Under an Application for
               Confidential Treatment];

          (c)  [*Material Omitted and Separately Filed Under an Application for
               Confidential Treatment];

          (d)  [*Material Omitted and Separately Filed Under an Application for
               Confidential Treatment].

6.   SERVICE LEVELS

     For each of the Service Levels set forth in this Article 6, scheduled
     maintenance by Vendor (or a third party) coordinated with Customer pursuant
     to Section 5.3(c)(i) of this Schedule C will be excluded from the Service
     Level performance calculations.

     6.1. Availability.
          ------------

          (a)  "Broadband Network Availability" for a calendar month is defined
               as the percentage calculated as (i) the total time in each month
               that [*Material Omitted and Separately Filed Under an Application
               for Confidential Treatment] is reachable through the [*Material
               Omitted and Separately Filed Under an Application for
               Confidential Treatment] from the [*Material

--------------------------------------------------------------------------------
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<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

               Omitted and Separately Filed Under an Application for
               Confidential Treatment] and vice-versa, divided by (ii) the sum
               of the total time in such month.

          (b)  The Service Level applicable to Broadband Network Availability
               for a calendar month shall be as follows: Broadband Network
               Availability for each calendar month shall exceed [*Material
               Omitted and Separately Filed Under an Application for
               Confidential Treatment] percent [*Material Omitted and Separately
               Filed Under an Application for Confidential Treatment]. Vendor
               shall provide Customer on a daily basis with reports on Broadband
               Network Availability, and Vendor's performance relative to such
               Service Level shall be measured on a monthly basis for each
               calendar month.

          (c)  In the event that Broadband Network Availability is below
               [*Material Omitted and Separately Filed Under an Application for
               Confidential Treatment] percent ([*Material Omitted and
               Separately Filed Under an Application for Confidential Treatment]
               %) as measured in [*Material Omitted and Separately Filed Under
               an Application for Confidential Treatment], such event shall
               constitute a material breach of the Agreement.

     6.2. Packet Loss.
          -----------

          (a)  "Broadband Packet Loss Percentage" means, for a calendar month,
               the quantity calculated as (i) the aggregate number of data
               packets dropped from the Vendor Network between the [*Material
               Omitted and Separately Filed Under an Application for
               Confidential Treatment], divided by (ii) the aggregate number of
               all data packets introduced into the Vendor Network between the
               [*Material Omitted and Separately Filed Under an Application for
               Confidential Treatment], during such month, the result expressed
               as a percentage.

          (b)  The Service Level applicable to Broadband Packet Loss Percentage
               shall be as follows: Broadband Packet Loss Percentage for each
               calendar month shall be less than or equal to [*Material Omitted
               and Separately Filed Under an Application for Confidential
               Treatment] percent ([*Material Omitted and Separately Filed Under
               an Application for Confidential Treatment]%) for such month.
               Vendor shall provide Customer on a daily basis with reports on
               Broadband Packet Loss Percentage, and Vendor's performance
               relative to such Service Level shall be measured on a monthly
               basis for each calendar month.

     6.3. Failed Sessions.

          (a)  "Failed Sessions" means point-to-point protocol sessions that are
               successfully placed to the [*Material Omitted and Separately
               Filed Under an Application for Confidential Treatment] and which
               do not fail as a result of problems with[*Material Omitted and
               Separately Filed Under an Application for Confidential
               Treatment].

          (b)  The Service Level applicable to Failed Sessions shall be that no
               more than [*Material Omitted and Separately Filed Under an
               Application for

--------------------------------------------------------------------------------
Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Schedule C                   Schedule C - Page 15
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

               Confidential Treatment] percent ([*Material Omitted and
               Separately Filed Under an Application for Confidential
               Treatment]%) of [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment] that are successfully
               placed [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment] during the month shall be
               Failed Sessions. Vendor shall provide Customer on a daily basis
               with reports on Failed Sessions, and Vendor's performance
               relative to such Service Level shall be measured on a monthly
               basis for each calendar month.

     6.4. Abnormal Disconnects.

          (a)  "Broadband Abnormal Disconnect Percentage" means, for each
               calendar day of the Broadband Term, the amount calculated as (i)
               the aggregate number of disconnected sessions utilizing the
               Broadband Backhaul Services during such day that are not
               initiated by a user logoff sequence and that are caused by
               problems in the network between [*Material Omitted and Separately
               Filed Under an Application for Confidential Treatment], divided
               by (ii) the aggregate number of all sessions utilizing the
               Broadband Backhaul Services commencing during such calendar day,
               with the result expressed as a percentage. "Monthly Broadband
               Abnormal Disconnect Percentage" means, for each calendar month of
               the Broadband Term, the amount calculated as (x) the
               percentage-point aggregate of the Broadband Abnormal Disconnect
               Percentages for such calendar month, divided by (y) the aggregate
               number of calendar days in such calendar month.

          (b)  The Service Level applicable to Monthly Broadband Abnormal
               Disconnect Percentage shall be as follows: Monthly Broadband
               Abnormal Disconnect Percentage during a calendar month shall not
               exceed [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment] percent ([*Material
               Omitted and Separately Filed Under an Application for
               Confidential Treatment]%). Vendor's performance relative to such
               Service Level shall be reported by Customer on a monthly basis
               for each calendar month, if technically feasible.

     6.5. Failure to Perform.

          (a)  If Vendor fails to meet any Service Level, Vendor shall (i)
               promptly notify Customer of such failure (unless Customer first
               discovered and notified Vendor of such failure), (ii) investigate
               and report on the causes of the failure; (iii) advise Customer,
               as and to the extent requested by Customer, of the status of
               remedial efforts being undertaken with respect to such failure;
               (iv) take commercially reasonable efforts to correct the failure,
               and begin meeting the Service Levels; and (v) take appropriate
               preventive measures to minimize the likelihood of the failure
               recurring.

          (b)  Notwithstanding the foregoing, Vendor's failure to meet or
               correct Service Level failures under this Schedule C during the
               first six months following the Effective Date shall not
               constitute a breach of the Agreement.

--------------------------------------------------------------------------------
Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Schedule C                   Schedule C - Page 16
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

          (c)  Notwithstanding the foregoing, Vendor's failure to use
               commercially reasonable efforts to meet or correct Service Level
               failures with respect to the Abnormal Disconnects in and of
               itself shall not constitute a breach of the Agreement.

          (d)  Vendor shall not be deemed in breach of such Service Levels to
               the extent that such breach is attributable to the offered data
               load from Customer data centers or subscribers exceeding the
               specified bandwidth per user or Customer having oversubscribed
               the intra-LATA interconnect circuits.

          (e)  Notwithstanding anything to the contrary to this Agreement, under
               no circumstances shall Customer be permitted to terminate any
               portion of the Agreement other than this Schedule C as a result
               of any material breaches, whether cured or uncured, of the
               Service Levels in this Schedule C.

     6.6. Meetings.
          --------

          Vendor and Customer shall hold weekly meetings at Customer's site or
          via telephone conference call (unless otherwise requested by Customer)
          to assess Vendor's performance under this Schedule C. During emergency
          situations, meetings will be held at least on a daily basis.

     6.7. Periodic Review of Service Levels.
          ---------------------------------

          As requested by Customer or Vendor, Customer and Vendor shall review
          the Service Levels described in this Schedule C and shall make
          mutually agreed-upon adjustments to them as appropriate to reflect
          performance capabilities associated with advances in the technology
          and methods used to provide the Broadband Backhaul Services.

7.   PRICING

     7.1. Charges for Broadband Backhaul Services.
          ---------------------------------------

          (a)  The monthly charges for the Broadband Backhaul Services shall be
               computed as the applicable Monthly Aggregate Subscriber Line
               Charges calculated pursuant to Exhibit C-2 plus the Monthly
               Pass-Through Expenses calculated pursuant to Subsection (b) of
               this Section.

          (b)  Monthly Pass-Through Expenses.
               -----------------------------

               (i)  "Monthly Pass-Through Expenses" means the following
                    third-party charges incurred by Vendor to provide the
                    Broadband Backhaul Services (including Broadband Backhaul
                    Services not yet accepted by Customer) during a calendar
                    month of the Broadband Term, for which Customer shall
                    reimburse Vendor on an Out-of-Pocket Expenses basis:

                    (1)  Third-party charges for the [*Material Omitted and
                         Separately Filed Under an Application for Confidential
                         Treatment] is necessary to provide the Broadband
                         Backhaul Services; and

--------------------------------------------------------------------------------
Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Schedule C                   Schedule C - Page 17
<PAGE>

                     (2)  Third-party charges approved in advance by Customer
                          for the acquisition of hub equipment at Customer's
                          facilities.

               (ii)  Vendor shall act as payment agent for Customer with respect
                     to the Monthly Pass-Through Expenses and shall pay the
                     corresponding third-party charges comprising the Monthly
                     Pass-Through Expenses.

               (iii) Vendor shall use commercially reasonable efforts to
                     minimize the amount of Monthly Pass-Through Expenses, by
                     among other means identifying and considering multiple
                     sources for the services and materials corresponding to
                     such expenses.

     7.2. Adjustments to Pricing for Services.
          -----------------------------------

          (a)  Broadband Backhaul Market Price.
               --------------------------------

               (i)  Definitions.

                    (1)  "New Broadband Backhaul Market Price" shall mean the
                         price (or, if applicable, prices and corresponding
                         volumes) [*Material Omitted and Separately Filed Under
                         an Application for Confidential Treatment] by any
                         [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment]. To calculate
                         the New Broadband Backhaul Market Price pursuant to
                         this Subsection, the price for Comparable Broadband
                         Backhaul Services shall be reasonably adjusted to
                         reflect the difference between [*Material Omitted and
                         Separately Filed Under an Application for Confidential
                         Treatment] and the provision of [*Material Omitted and
                         Separately Filed Under an Application for Confidential
                         Treatment] by a [*Material Omitted and Separately Filed
                         Under an Application for Confidential Treatment] that
                         (A) do not [*Material Omitted and Separately Filed
                         Under an Application for Confidential Treatment],or (B)
                         do not [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment].

                    (2)  "Broadband Backhaul Market Vendor" shall mean a vendor
                         (not including a Special Affiliate) that at any time
                         [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment]. For the
                         purpose of this Subsection, Special Affiliate shall
                         only be deemed to include Subsections (i) and (ii) of
                         the definition of "Special Affiliate" in Schedule A.

               (ii) Notification Process.

                    Customer may provide Vendor with notice at any time of a New
                    Broadband Backhaul Market Price (each such notice, a "New
                    Broadband Backhaul Market Price Notice" and the date of such

--------------------------------------------------------------------------------
Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Schedule C                   Schedule C - Page 18
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

                    notice as determined pursuant to Section 16.4 of the Master
                    Agreement, the "New Broadband Backhaul Market Price Notice
                    Date"). Each New Broadband Backhaul Market Price Notice will
                    contain (A) the New Broadband Backhaul Market Price
                    calculation and [*Material Omitted and Separately Filed
                    Under an Application for Confidential Treatment] of the
                    [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment] to which such [*Material Omitted
                    and Separately Filed Under an Application for Confidential
                    Treatment] relates, and (B) information sufficient to enable
                    [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment] per [*Material Omitted and
                    Separately Filed Under an Application for Confidential
                    Treatment] at [*Material Omitted and Separately Filed Under
                    an Application for Confidential Treatment] corresponding to
                    the [*Material Omitted and Separately Filed Under an
                    Application for Confidential Treatment] if requested by
                    customer. No later than thirty (30) calendar days after the
                    Broadband Backhaul Market Price Notice Date corresponding to
                    a New Broadband Backhaul Market Price Notice, Vendor will
                    respond to Customer by notifying Customer in writing whether
                    it will:

                    (1)  accept the validity of the proposed New Broadband
                         Backhaul Market Price and reduce prices to the
                         applicable New Broadband Backhaul Market Price in
                         accordance with Subsection (iii) of this Subsection
                         (a),

                    (2)  accept the validity of the proposed New Broadband
                         Backhaul Market Price and decline to reduce prices to
                         the New Broadband Backhaul Market Price in accordance
                         with Subsection (iii) of this Subsection (a), or

                    (3)  dispute the validity of the proposed New Broadband
                         Backhaul Market Price

                    (each a "New Broadband Backhaul Market Price Response").
                    Vendor shall not unreasonably dispute the validity of a
                    proposed New Broadband Backhaul Market Price.

              (iii) Reduction Process.

                    In the event Vendor accepts a proposed New Broadband
                    Backhaul Market Price pursuant to clause (1) of Subsection
                    (ii) of this Subsection (a), then effective as of the later
                    of (a) the New Broadband Backhaul Market Price Effective
                    Date corresponding to such New Broadband Backhaul Market
                    Price Notice, and (b) [*Material Omitted and Separately
                    Filed Under an Application for Confidential Treatment], the
                    Monthly Per Subscriber Line Charge will be reduced to the
                    New Broadband Backhaul Market Price set forth in the
                    corresponding New Broadband Backhaul Market Price Notice,
                    and with respect to such

--------------------------------------------------------------------------------
Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Schedule C                   Schedule C - Page 19
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

                    Broadband Backhaul Services, Vendor will, if requested by
                    Customer, [*Material Omitted and Separately Filed Under an
                    Application for Confidential Treatment] per [*Material
                    Omitted and Separately Filed Under an Application for
                    Confidential Treatment] at [*Material Omitted and Separately
                    Filed Under an Application for Confidential Treatment] or
                    the [*Material Omitted and Separately Filed Under an
                    Application for Confidential Treatment] corresponding to
                    such New Broadband Backhaul Market Price; provided, however,
                    that Vendor shall not be obligated to reduce the Monthly Per
                    Subscriber Line Charge [*Material Omitted and Separately
                    Filed Under an Application for Confidential Treatment] for
                    which Vendor reduced prices pursuant to this Subsection
                    (iii).

                    Notwithstanding the foregoing:

                    (1)  Vendor shall not be obligated to reduce the Monthly Per
                         Subscriber Line Charge at a rate that is more rapid
                         than the rate at which the [*Material Omitted and
                         Separately Filed Under an Application for Confidential
                         Treatment] provides Customer with [*Material Omitted
                         and Separately Filed Under an Application for
                         Confidential Treatment] relative to the applicable
                         [*Material Omitted and Separately Filed Under an
                         Application for Confidential Treatment], as measured
                         monthly.

                    Example 1 - Straight Percentage Commitment: For example, if
                    the [*Material Omitted and Separately Filed Under an
                    Application for Confidential Treatment] has committed to
                    provide [*Material Omitted and Separately Filed Under an
                    Application for Confidential Treatment] with [*Material
                    Omitted and Separately Filed Under an Application for
                    Confidential Treatment] for [*Material Omitted and
                    Separately Filed Under an Application for Confidential
                    Treatment] or more of the [*Material Omitted and Separately
                    Filed Under an Application for Confidential Treatment] (in
                    terms of a percentage commitment) at the [*Material Omitted
                    and Separately Filed Under an Application for Confidential
                    Treatment], but immediately following the [*Material Omitted
                    and Separately Filed Under an Application for Confidential
                    Treatment] has only provided [*Material Omitted and
                    Separately Filed Under an Application for Confidential
                    Treatment] with [*Material Omitted and Separately Filed
                    Under an Application for Confidential Treatment] for
                    [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment] percent [*Material Omitted and
                    Separately Filed Under an Application for Confidential
                    Treatment] of the [*Material Omitted and Separately Filed
                    Under an Application for Confidential Treatment] at the
                    [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment], then Vendor will only be
                    obligated to reduce the Monthly Per Subscriber

--------------------------------------------------------------------------------
Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Schedule C                   Schedule C - Page 20
<PAGE>

                    CONFIDENTIAL TREATMENT REQUESTED

                    Line Charge for [*Material Omitted and Separately Filed
                    Under an Application for Confidential Treatment] percent
                    [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment] of the [*Material Omitted and
                    Separately Filed Under an Application for Confidential
                    Treatment] as of the applicable month. If during the
                    following month the [*Material Omitted and Separately Filed
                    Under an Application for Confidential Treatment] has
                    provided [*Material Omitted and Separately Filed Under an
                    Application for Confidential Treatment] for an additional
                    [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment] percent [*Material Omitted and
                    Separately Filed Under an Application for Confidential
                    Treatment] of the [*Material Omitted and Separately Filed
                    Under an Application for Confidential Treatment] at the
                    [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment], then Vendor will be obligated
                    to reduce the Monthly Per Subscriber Line Charge for
                    [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment] percent [*Material Omitted and
                    Separately Filed Under an Application for Confidential
                    Treatment] of the [*Material Omitted and Separately Filed
                    Under an Application for Confidential Treatment] as of the
                    applicable month.

                    Example 2 - Actual Volume Commitment: For example, if,
                    instead, the [*Material Omitted and Separately Filed Under
                    an Application for Confidential Treatment] has committed to
                    provide [*Material Omitted and Separately Filed Under an
                    Application for Confidential Treatment] with [*Material
                    Omitted and Separately Filed Under an Application for
                    Confidential Treatment] for [*Material Omitted and
                    Separately Filed Under an Application for Confidential
                    Treatment] at the [*Material Omitted and Separately Filed
                    Under an Application for Confidential Treatment] and at the
                    time that [*Material Omitted and Separately Filed Under an
                    Application for Confidential Treatment] provides [*Material
                    Omitted and Separately Filed Under an Application for
                    Confidential Treatment] with the [*Material Omitted and
                    Separately Filed Under an Application for Confidential
                    Treatment] is [*Material Omitted and Separately Filed Under
                    an Application for Confidential Treatment], then the
                    [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment] has been met because it meets
                    the [*Material Omitted and Separately Filed Under an
                    Application for Confidential Treatment]. If as of the New
                    Broadband Backhaul Market Price Effective Date, such
                    [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment] has provided [*Material Omitted
                    and Separately Filed Under an Application for Confidential
                    Treatment] with [*Material Omitted and Separately Filed
                    Under an Application for Confidential Treatment] for
                    [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment] of the [*Material Omitted

--------------------------------------------------------------------------------
Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Schedule C                   Schedule C - Page 21
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

                    and Separately Filed Under an Application for Confidential
                    Treatment] committed [*Material Omitted and Separately Filed
                    Under an Application for Confidential Treatment] at the
                    [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment] but [*Material Omitted and
                    Separately Filed Under an Application for Confidential
                    Treatment] has grown to [*Material Omitted and Separately
                    Filed Under an Application for Confidential Treatment], then
                    Vendor will only be obligated to reduce the Monthly Per
                    Subscriber Line Charge for [*Material Omitted and Separately
                    Filed Under an Application for Confidential Treatment]
                    percent [*Material Omitted and Separately Filed Under an
                    Application for Confidential Treatment] of the [*Material
                    Omitted and Separately Filed Under an Application for
                    Confidential Treatment] as of the applicable month (i.e.,
                    because the [*Material Omitted and Separately Filed Under an
                    Application for Confidential Treatment] being serviced by
                    the [*Material Omitted and Separately Filed Under an
                    Application for Confidential Treatment] only represents
                    [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment]. If in the following month,
                    [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment] has provided [*Material Omitted
                    and Separately Filed Under an Application for Confidential
                    Treatment] with [*Material Omitted and Separately Filed
                    Under an Application for Confidential Treatment] for all
                    [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment] at the [*Material Omitted and
                    Separately Filed Under an Application for Confidential
                    Treatment] and [*Material Omitted and Separately Filed Under
                    an Application for Confidential Treatment] has remained at
                    [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment], then Vendor will be obligated
                    to reduce the Monthly Per Subscriber Line Charge for
                    [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment] of the [*Material Omitted and
                    Separately Filed Under an Application for Confidential
                    Treatment] as of such month (i.e., because the [*Material
                    Omitted and Separately Filed Under an Application for
                    Confidential Treatment] being serviced by the [*Material
                    Omitted and Separately Filed Under an Application for
                    Confidential Treatment]. If in following month, [*Material
                    Omitted and Separately Filed Under an Application for
                    Confidential Treatment] has provided [*Material Omitted and
                    Separately Filed Under an Application for Confidential
                    Treatment] for an aggregate [*Material Omitted and
                    Separately Filed Under an Application for Confidential
                    Treatment], then Vendor will be obligated to reduce the
                    Monthly Per Subscriber Line Charge [*Material Omitted and
                    Separately Filed Under an Application for Confidential
                    Treatment] of the [*Material Omitted and Separately Filed
                    Under an Application for Confidential Treatment] as of such
                    month (because the [*Material Omitted and Separately Filed
                    Under an Application for Confidential Treatment]

--------------------------------------------------------------------------------
Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
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<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED


                    being serviced by the [*Material Omitted and Separately
                    Filed Under an Application for Confidential Treatment]. If
                    in the following month, [*Material Omitted and Separately
                    Filed Under an Application for Confidential Treatment] has
                    provided [*Material Omitted and Separately Filed Under an
                    Application for Confidential Treatment] for the same
                    aggregate [*Material Omitted and Separately Filed Under an
                    Application for Confidential Treatment] at the [*Material
                    Omitted and Separately Filed Under an Application for
                    Confidential Treatment] and [*Material Omitted and
                    Separately Filed Under an Application for Confidential
                    Treatment] has grown to [*Material Omitted and Separately
                    Filed Under an Application for Confidential Treatment] there
                    will be no reduction in the percentage of [*Material Omitted
                    and Separately Filed Under an Application for Confidential
                    Treatment] which have the [*Material Omitted and Separately
                    Filed Under an Application for Confidential Treatment].

                    (2)  Vendor shall not be obligated [*Material Omitted and
                         Separately Filed Under an Application for Confidential
                         Treatment] provides [*Material Omitted and Separately
                         Filed Under an Application for Confidential Treatment]
                         relative to the applicable [*Material Omitted and
                         Separately Filed Under an Application for Confidential
                         Treatment], as measured monthly.

                    (3)  A New Broadband Backhaul Market Price shall be
                         applicable only during such periods as [*Material
                         Omitted and Separately Filed Under an Application for
                         Confidential Treatment] actually [*Material Omitted and
                         Separately Filed Under an Application for Confidential
                         Treatment], or a lower price, from a [*Material Omitted
                         and Separately Filed Under an Application for
                         Confidential Treatment].

               (iv) Decommissioning Process.

                    If Vendor declines to reduce the Monthly Per Subscriber Line
                    Charge to the New Broadband Backhaul Market Price pursuant
                    to clause (2) of Subsection (ii) of this Subsection (a),
                    then Customer may, in its sole discretion, do either or both
                    of the following: (A) terminate the Broadband Backhaul
                    Purchase Commitment, and (B) disconnect Vendor Broadband
                    Subscriber Lines from the Vendor Network, subject to the
                    following restrictions:

                    (1)  Customer will provide [*Material Omitted and Separately
                         Filed Under an Application for Confidential Treatment]
                         days prior written notice of the LATA or other
                         geographic area in which Vendor Broadband Subscriber
                         Lines are to be disconnected from the Vendor Network,
                         as well as the


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<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED


                         associated quantities of Vendor Broadband Subscriber
                         Lines to be disconnected in each such LATA or other
                         geographic area.

                    (2)  Customer may not order the disconnection of Vendor
                         Broadband Backhaul Subscriber Lines from the Vendor
                         Network in amounts greater than the number of the
                         Aggregate Subscriber Lines utilizing Comparable
                         Broadband Backhaul Services that are provided to
                         Customer by other entities at or below such New
                         Broadband Backhaul Market Price.

                    (3)  The disconnection of Vendor Broadband Subscriber Lines
                         from the Vendor Network pursuant to this Subsection
                         7.2(a)(iv) shall result in the same approximate
                         weighted distribution of Vendor Broadband Subscriber
                         Lines across all Existing LATAs. For the purposes of
                         this Subsection (3), "distribution" means the
                         distribution of the corresponding Subscriber Lines
                         across rural versus urban areas, across the contiguous
                         states of the United States, and between Covered
                         Subscriber Lines and non-Covered Subscriber Lines.

               (v)  Dispute Resolution Process.

                    If Vendor reasonably disputes the validity of the New
                    Broadband Backhaul Market Price pursuant to clause (3) of
                    Subsection (ii) of this Subsection (a), then each Party
                    shall promptly escalate to the senior-executive level all
                    efforts by such Party to resolve such dispute.

          (b)  Most-Favored Customer.
               ---------------------

               (i)  As long as the aggregate number of Vendor Broadband
                    Subscriber Lines exceeds that of any other customer of
                    Vendor, Vendor shall not provide Comparable Broadband
                    Backhaul Services to any other Applicable BB Purchaser (1)
                    at prices that are lower than those charged or available to
                    Customer under this Agreement, or (2) pursuant to terms and
                    conditions more favorable to such Applicable BB Purchaser
                    than the terms and conditions of this Schedule C and Master
                    Agreement, in each case, without offering such lower price
                    and other more favorable terms and conditions to Customer
                    within thirty (30) calendar days of contractually committing
                    to such price and other terms with another customer. For the
                    purposes of this Subsection, prices "charged or available to
                    Customer under this Agreement" for Broadband Backhaul
                    Services shall be a [*Material Omitted and Separately Filed
                    Under an Application for Confidential Treatment] of all
                    [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment] hereunder. In the event that the
                    aggregate number of Vendor Broadband Subscriber Lines then
                    being purchased or ordered by Customer at any time during
                    the Broadband Term exceeds that of any other customer of
                    Vendor, Vendor shall provide Customer with written
                    notification of such


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Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Schedule C                    Schedule C - Page 24
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

                    event within thirty (30) calendar days of the occurrence of
                    such event, and thereafter, once the aggregate number of
                    Vendor Broadband Subscriber Lines then being purchased or
                    ordered by Customer falls below that of any other customer
                    of Vendor, Vendor shall provide Customer with written
                    notification of such event within thirty (30) calendar days
                    of the occurrence of such event. "Applicable BB Purchaser"
                    shall mean any party (including any Vendor Affiliate that
                    resells Broadband Backhaul Services purchased from Vendor)
                    that is obligated to purchase, that actually purchases, or
                    that seeks to purchase from Vendor Broadband Backhaul
                    Services at any time for more than the Applicable BB Volume
                    for the then-current calendar year. "Applicable BB Volume"
                    means (A) [*Material Omitted and Separately Filed Under an
                    Application for Confidential Treatment] subscriber lines,
                    (B) [*Material Omitted and Separately Filed Under an
                    Application for Confidential Treatment] subscriber lines,
                    (C) [*Material Omitted and Separately Filed Under an
                    Application for Confidential Treatment] subscriber lines,
                    (D) [*Material Omitted and Separately Filed Under an
                    Application for Confidential Treatment] subscriber lines,
                    and (E) [*Material Omitted and Separately Filed Under an
                    Application for Confidential Treatment] subscriber lines.

              (ii)  As long as the aggregate number of Vendor Broadband
                    Subscriber Lines exceeds that of any other customer of
                    Vendor, to the extent that Vendor provides broadband
                    backhaul services that are not Comparable Broadband Backhaul
                    Services, then Vendor shall offer, on a quarterly basis, to
                    provide to Customer such broadband backhaul services at the
                    prices charged or available to, and upon the terms and
                    conditions applicable to, any Applicable BB Purchaser;
                    provided, however, that if Customer's service requirements
                    would necessitate changes to such terms and conditions, the
                    Parties shall work in good faith to adjust such terms and
                    conditions as mutually agreed to satisfy such requirements.
                    To the extent that Customer accepts such offer of broadband
                    backhaul services that are not Comparable Broadband Backhaul
                    Services from Vendor, Vendor shall provide such services
                    pursuant to a separate Schedule to the Master Agreement,
                    such services shall be deemed Services to which the Master
                    Agreement applies, and such services shall be subject to
                    most-favored customer terms and conditions substantially
                    similar to those set forth in this Subsection (b), and any
                    such services will contribute toward [*Material Omitted and
                    Separately Filed Under an Application for Confidential
                    Treatment] on an equitable basis. For purposes of this
                    Subsection (ii), broadband backhaul services that are not
                    Comparable Broadband Backhaul Services include, but are not
                    limited to, an end-to-end broadband service which includes
                    the local loop, and usage-based broadband backhaul services.

              (iii) As long as the aggregate number of Vendor Subscriber Lines
                    exceeds that of any other customer of Vendor, Vendor shall
                    offer to Customer




--------------------------------------------------------------------------------
Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Schedule C                    Schedule C - Page 25
<PAGE>

                    CONFIDENTIAL TREATMENT REQUESTED


                    Comparable Broadband Backhaul Services provided or offered
                    by any Vendor Affiliate to an Applicable BB Purchaser (1) at
                    prices that are equal to or lower than those charged or
                    available to such Applicable BB Purchaser for such services,
                    and (2) pursuant to terms and conditions that are at least
                    as favorable to Customer than the terms and conditions
                    applicable to or available to an Applicable BB Purchaser.

               (iv) For any price proposal made by Vendor to Customer at any
                    time during the Term, Vendor shall in good faith represent
                    to Customer in writing whether or not such proposal is being
                    made for reasons that include Vendor's belief that an
                    adjustment may be required pursuant to this Subsection (b).

               (v)  Customer may audit Vendor's compliance with this Subsection
                    (b) pursuant to Article 10 of the Master Agreement. In the
                    event that Vendor fails to comply with this Subsection (b)
                    (e.g., fails to adjust pricing in accordance with this
                    Subsection (b)), then Vendor shall rebate to Customer, with
                    respect to the aggregate volume of Broadband Backhaul
                    Services purchased hereunder, the difference between (1) the
                    price actually paid by Customer hereunder, and (2) the lower
                    price provided to the Applicable BB Purchaser, retroactive
                    to the date Vendor committed to provide the lower price to
                    such Applicable BB Purchaser, together with interest
                    computed in the same manner as described in Section 9.2 of
                    the Master Agreement on such rebated amounts from such date.

8.   SPECIFICATIONS

     The Broadband Backhaul Services provided hereunder shall fully conform with
     the following Specifications (collectively, the "Broadband
     Specifications"):

          (a)  Vendor will provision end-to-end bandwidth such that [*Material
               Omitted and Separately Filed Under an Application for
               Confidential Treatment]. For each [*Material Omitted and
               Separately Filed Under an Application for Confidential Treatment]
               Line that Customer requests Vendor to provide hereunder, Vendor
               shall provide [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment] at a charge to Customer
               that is no greater than [*Material Omitted and Separately Filed
               Under an Application for Confidential Treatment] cents
               ($[*Material Omitted and Separately Filed Under an Application
               for Confidential Treatment]) [*Material Omitted and Separately
               Filed Under an Application for Confidential Treatment].

          (b)  Each circuit used to provide Broadband Backhaul Services between
               the Vendor Network and Customer's facilities shall have capacity
               equal to or greater than DS-3.



--------------------------------------------------------------------------------
Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Schedule C                    Schedule C - Page 26
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED



          (c)  Aggregation router equipment will be fully compliant with (i)
               [*Material Omitted and Separately Filed Under an Application for
               Confidential Treatment],and (ii) [*Material Omitted and
               Separately Filed Under an Application for Confidential Treatment]
               for [*Material Omitted and Separately Filed Under an Application
               for Confidential Treatment] set forth in [*Material Omitted and
               Separately Filed Under an Application for Confidential Treatment]
               effective [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment], as such referenced
               specifications may change from time to time, provided that Vendor
               shall not be required to replace aggregation router equipment to
               meet any changed specifications, but shall be required to
               implement any software provided by the manufacturer of such
               aggregation router equipment within a commercially reasonable
               period of time after such software is provided and after
               successful testing by Vendor.

          (d)  If Vendor changes aggregation router equipment, it will be fully
               functional with services provided by Customer without
               modification of, or addition to, client or host software used to
               provide services provided by Customer that utilize the Broadband
               Backhaul Services. As of the Effective Date, aggregation router
               equipment must comply with the following protocol requirements in
               order to comply with the requirements of this Subsection (d):

               (i)  [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment] ; and

               (ii) [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment].

          (e)  The Broadband Backhaul Services will support the following
               software features being developed for Customer[*Material Omitted
               and Separately Filed Under an Application for Confidential
               Treatment] as of the Effective Date:

               (i)   [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] ;

               (ii)  [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment];

               (iii) [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment];

               (iv)  [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment];

               (v)   [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment];

               (vi)  [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment];



--------------------------------------------------------------------------------
Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Schedule C                    Schedule C - Page 27
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED


               (vii)  [*Material Omitted and Separately Filed Under an
                      Application for Confidential Treatment];

               (viii) [*Material Omitted and Separately Filed Under an
                      Application for Confidential Treatment];

               (ix)   [*Material Omitted and Separately Filed Under an
                      Application for Confidential Treatment];

               (x)    [*Material Omitted and Separately Filed Under an
                      Application for Confidential Treatment]

               (xi)   [*Material Omitted and Separately Filed Under an
                      Application for Confidential Treatment].

               The Parties acknowledge and agree that as of the Effective Date,
               the Redback Networks Inc. ("Redback") router aggregation
               equipment utilized to provide the Broadband Backhaul Services as
               of the Effective Date satisfy the Broadband Specifications set
               forth in Subsections (c) and (d) of this Article 8. The Broadband
               Backhaul Services will support any additional software features
               provided by the aggregation router vendor after the Effective
               Date as mutually agreed by the Parties. Vendor shall use
               commercially reasonable efforts to cause [*Material Omitted and
               Separately Filed Under an Application for Confidential Treatment]
               to provide those features described in this Subsection (e).

          (f)  Any Broadband Backhaul Market Vendor shall support the Broadband
               Specifications set forth in Subsections (c), (d) and (e) of this
               Article 8 in a manner comparable to that required of Vendor
               pursuant to such Subsections.

          The Parties acknowledge and agree that this Article 8 does not set
          forth a complete listing of required specifications applicable to
          Broadband Backhaul Services that are used to provide any non-xDSL
          services. Any such specifications not set forth in this Article 8
          shall be mutually agreed upon by the Parties pursuant to Article 2 of
          this Schedule C.

9.   LIABILITY RESTRICTIONS

          (a)  Subject to Subsection (d) of this Section, the liability of
               Vendor to Customer for all damages arising out of or related to
               the Services provided under this Schedule will be limited to, and
               will not exceed, in the aggregate during any calendar year, ten
               percent (10%) of the aggregate amounts paid to Vendor by Customer
               (excluding Out-of-Pocket Expenses and Monthly Pass-Through
               Expenses) under this Schedule during the twelve (12) month period
               preceding the date of the event giving rise to such damages;
               provided, however, for the initial twelve (12) months following
               the Effective Date, the foregoing cap shall be no less than Five
               Million Dollars ($5,000,000). Subject to Subsections (b) and (d)
               of this Section, the liability of Vendor to Customer for damages
               arising out of or related



--------------------------------------------------------------------------------
Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Schedule C                    Schedule C - Page 28
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED


               to Services provided under this Schedule caused by the acts or
               omissions of third parties beyond the reasonable control of
               Vendor will be further limited and will not exceed, in the
               aggregate during any calendar year, the lesser of (i) five
               percent (5%) of the aggregate amounts paid to Vendor by Customer
               (excluding Out-of-Pocket Expenses and Monthly Pass-Through
               Expenses) under this Schedule during the twelve (12) month period
               preceding the date of the event giving rise to such damages, or
               (ii) Ten Million Dollars ($10,000,000); provided, however, for
               the initial twelve (12) months following the Effective Date, the
               foregoing cap shall be no less than Three Million Dollars
               ($3,000,000).

          (b)  In the event of any liability of Vendor to Customer for damages
               arising out of or related to Services provided under this
               Schedule caused by the acts or omissions of third parties beyond
               the reasonable control of Vendor, then the Parties agree as
               follows:

               (i)   Vendor agrees to vigorously pursue the recovery of damages
                     against the third party causing the damage, including
                     through negotiations, dispute resolution, or both, to
                     maximize the damages recoverable against such third party;

               (ii)  Vendor agrees to pass through to Customer any amounts that
                     Vendor actually recovers from such third party relating to
                     damages incurred in connection with Services provided to
                     Customer under this Schedule;

               (iii) Customer agrees that in the event that Vendor has paid any
                     amounts to Customer pursuant to Subsection (a) of this
                     Section prior to the recovery of damages from a third
                     party, Vendor may reduce the amount of recovery received
                     from such third party by the amount previously paid to
                     Customer in respect of such event causing the damages; and

               (iv)  Amounts recovered by Vendor from third parties shall be
                     first passed on to Customer until Customer's full damages
                     are satisfied.

          (c)  IN NO EVENT, WHETHER IN CONTRACT OR IN TORT (INCLUDING BREACH OF
               WARRANTY, NEGLIGENCE AND STRICT LIABILITY IN TORT), SHALL A PARTY
               BE LIABLE TO THE OTHER PARTY FOR INDIRECT OR CONSEQUENTIAL,
               EXEMPLARY, PUNITIVE OR SPECIAL DAMAGES EVEN IF SUCH PARTY HAS
               BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES IN ADVANCE.

          (d)  The limitations set forth in Subsection (a) of this Section shall
               not apply with respect to (i) intentional breach by Vendor; (ii)
               damages occasioned by an intentional tort or the gross negligence
               of Vendor; (iii) damages occasioned by Vendor' breach of its
               obligations described in Article 11 (Confidentiality) of the
               Master Agreement, or (iv) claims subject to indemnification
               pursuant to this Agreement (such amounts paid by the indemnitee
               to third parties shall be deemed to be direct damages) other than
               claims subject to the indemnity set forth in Section 15(a) of the
               Master Agreement.

--------------------------------------------------------------------------------
Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Schedule C                    Schedule C - Page 29
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED


          (e)  Each Party shall have a duty to reasonably mitigate (i.e.,
               minimize) damages for which the other Party is responsible.




--------------------------------------------------------------------------------
Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Schedule C                    Schedule C - Page 30
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED


                                   EXHIBIT C-1

                    Broadband Backhaul Purchase Commitment

1.   Confidentiality

     This Exhibit specifies Customer's Broadband Backhaul Purchase Commitments
     pursuant to Schedule C. The Parties specifically acknowledge that the
     purchase commitment information contained herein is highly confidential and
     that its disclosure to the public or third parties could cause significant
     harm to either Customer or Vendor or both.

2.   Broadband backhaul purchase commitments

     2.1. DSL Purchase Commitment.

          Customer agrees to order Broadband Backhaul Services such that:

          (a)  Commencing upon the Effective Date through [*Material Omitted and
               Separately Filed Under an Application for Confidential
               Treatment], no less than [*Material Omitted and Separately Filed
               Under an Application for Confidential Treatment] of the
               [*Material Omitted and Separately Filed Under an Application for
               Confidential Treatment] are [*Material Omitted and Separately
               Filed Under an Application for Confidential Treatment]; and

          (b)  Commencing upon [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment] through no less than
               [*Material Omitted and Separately Filed Under an Application for
               Confidential Treatment] of the [*Material Omitted and Separately
               Filed Under an Application for Confidential Treatment] are
               [*Material Omitted and Separately Filed Under an Application for
               Confidential Treatment].

     (such commitment, as may be reduced pursuant to the Agreement, the "DSL
     Purchase Commitment").

     2.2. Other Broadband Purchase Commitments.
          ------------------------------------

          Customer agrees to order Broadband Backhaul Services such that, during
          the [*Material Omitted and Separately Filed Under an Application for
          Confidential Treatment], no less than [*Material Omitted and
          Separately Filed Under an Application for Confidential Treatment] of
          the [*Material Omitted and Separately Filed Under an Application for
          Confidential Treatment] are [*Material Omitted and Separately Filed
          Under an Application for Confidential Treatment] such commitment as
          may be reduced pursuant to the [*Material Omitted and Separately Filed
          Under an Application for Confidential Treatment].

     2.3. Provision of Subscriber Line Information.
          ----------------------------------------

          Customer will provide Vendor with information regarding the number of
          Vendor [*Material Omitted and Separately Filed Under an Application
          for Confidential Treatment] relative to the [*Material Omitted and
          Separately Filed Under an Application for Confidential Treatment] and
          [*Material Omitted and Separately Filed Under an Application for
          Confidential Treatment] during each [*Material Omitted and Separately
          Filed Under an Application for Confidential Treatment] of each
          [*Material Omitted and Separately Filed Under an Application for
          Confidential Treatment] of the [*Material Omitted and Separately Filed
          Under an Application for Confidential Treatment].

3.   Reduction in Broadband Purchase Commitments for Delivery Failure

     3.1. Reduction Calculation.
          ---------------------


--------------------------------------------------------------------------------
Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Exhibit C-1 to Schedule C      Exhibit C-1 Page 1
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

          Reduction of the Broadband Backhaul Purchase Commitments pursuant to
          Section 3.2(b)(ii) of Schedule C shall be determined in accordance
          with this Section. As of the [*Material Omitted and Separately Filed
          Under an Application for Confidential Treatment] of each [*Material
          Omitted and Separately Filed Under an Application for Confidential
          Treatment], beginning on [*Material Omitted and Separately Filed Under
          an Application for Confidential Treatment]. the Parties will calculate
          [*Material Omitted and Separately Filed Under an Application for
          Confidential Treatment]from and after [*Material Omitted and
          Separately Filed Under an Application for Confidential Treatment] will
          equal the [*Material Omitted and Separately Filed Under an Application
          for Confidential Treatment] (1) [*Material Omitted and Separately
          Filed Under an Application for Confidential Treatment] as adjusted, as
          of the prior [*Material Omitted and Separately Filed Under an
          Application for Confidential Treatment] (2) either if (A) [*Material
          Omitted and Separately Filed Under an Application for Confidential
          Treatment] is on or before [*Material Omitted and Separately Filed
          Under an Application for Confidential Treatment] as measured at such
          [*Material Omitted and Separately Filed Under an Application for
          Confidential Treatment] (B) [*Material Omitted and Separately Filed
          Under an Application for Confidential Treatment] is on or after
          [*Material Omitted and Separately Filed Under an Application for
          Confidential Treatment] as measured at such [*Material Omitted and
          Separately Filed Under an Application for Confidential Treatment].

     3.2. Example of Reduction Calculation.
          --------------------------------

          This Section 3.2 sets forth examples, referenced in Section
          3.2(b)(iii) of Schedule C, of reductions in the Broadband Backhaul
          Purchase Commitments for delivery failures pursuant to Section 3.2(b)
          of Schedule C.

          (a)  As of [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment] within the [*Material
               Omitted and Separately Filed Under an Application for
               Confidential Treatment] have not yet been [*Material Omitted and
               Separately Filed Under an Application for Confidential
               Treatment]:

               (i)   [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment];

               (ii)  [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment];

               (iii) [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment];

               (iv)  [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] as of that
                     [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] equals the
                     [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment].

          (b)  As of [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment] in the applicable
               [*Material Omitted and Separately Filed Under an Application for
               Confidential Treatment] have not yet been [*Material Omitted and
               Separately Filed Under an Application for Confidential
               Treatment]:

               (i)   [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment];

               (ii)  [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment];

               (iii) [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment];

               (iv)  [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] as of that
                     [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] equals the
                     [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment].

--------------------------------------------------------------------------------
Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Exhibit C-1 to Schedule C      Exhibit C-1 - Page 2
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

          (c)  As of [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment] in the applicable
               [*Material Omitted and Separately Filed Under an Application for
               Confidential Treatment] have not yet been [*Material Omitted and
               Separately Filed Under an Application for Confidential
               Treatment]:

               (i)   [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment];

               (ii)  [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment];

               (iii) [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment];

               (iv)  [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] as of that
                     [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] equals the
                     [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment];

          (d)  As of[*Material Omitted and Separately Filed Under an Application
               for Confidential Treatment] in the applicable [*Material Omitted
               and Separately Filed Under an Application for Confidential
               Treatment] have not yet been [*Material Omitted and Separately
               Filed Under an Application for Confidential Treatment]:

               (i)   [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment];

               (ii)  [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment];

               (iii) [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment];

               (iv)  [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] as of that
                     [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] equals the
                     [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment].

--------------------------------------------------------------------------------
Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Exhibit C-1 to Schedule C      Exhibit C-1 - Page 3
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

                                   EXHIBIT C-2

                  Prices for Broadband Backhaul Access Services

1.   Confidentiality

     This Exhibit C-2 specifies the prices for Broadband Backhaul Services
     provided pursuant to the Master Agreement and Schedule C. The Parties
     specifically acknowledge that the pricing information contained herein is
     highly confidential and that its disclosure to the public or third parties
     could cause significant harm to either Customer or Vendor or both.

2.   PRICES FOR BROADBAND BACKHAUL SERVICES

     2.1. Monthly Per Subscriber Line Charge.
          ----------------------------------

          "Monthly Per Subscriber Line Charge" shall be defined as follows:

          (a)  If a Vendor Broadband Subscriber Line is a Covered Subscriber
               Line, and

               (i)   the Monthly Subscriber Line Aggregate is equal to or
                     greater than [*Material Omitted and Separately Filed Under
                     an Application for Confidential Treatment] but less than
                     [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] then the Monthly
                     Subscriber Per Line Charge shall be [*Material Omitted and
                     Separately Filed Under an Application for Confidential
                     Treatment];

               (ii)  the Monthly Subscriber Line Aggregate is greater than or
                     equal [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] but less than
                     [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] then the Monthly
                     Subscriber Per Line Charge shall be [*Material Omitted and
                     Separately Filed Under an Application for Confidential
                     Treatment];

               (iii) the Monthly Subscriber Line Aggregate is greater than or
                     equal to [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] but less than
                     [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] then the Monthly
                     Subscriber Per Line Charge shall be [*Material Omitted and
                     Separately Filed Under an Application for Confidential
                     Treatment];

               (iv)  the Monthly Subscriber Line Aggregate is greater than or
                     equal [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] but less than
                     [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] then the Monthly
                     Subscriber Per Line Charge shall be [*Material Omitted and
                     Separately Filed Under an Application for Confidential
                     Treatment];

--------------------------------------------------------------------------------
Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Exhibit C-2                     Exhibit C-2 - Page 1
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

               (v)  the Monthly Subscriber Line Aggregate is greater than or
                    equal to [*Material Omitted and Separately Filed Under an
                    Application for Confidential Treatment] but less than
                    [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment] then the Monthly Per Subscriber
                    Line Charge shall be [*Material Omitted and Separately Filed
                    Under an Application for Confidential Treatment].

               (vi) the Monthly Subscriber Line Aggregate is greater than
                    [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment]. then the Monthly Per Subscriber
                    Line Charge shall be [*Material Omitted and Separately Filed
                    Under an Application for Confidential Treatment].

          (b)  If a Vendor Broadband Subscriber Line is not a Covered Subscriber
               Line, and

               (i)   the Monthly Subscriber Line Aggregate is equal to or
                     greater than [*Material Omitted and Separately Filed Under
                     an Application for Confidential Treatment] but less than
                     [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] then the Monthly
                     Per Subscriber Line Charge shall be [*Material Omitted and
                     Separately Filed Under an Application for Confidential
                     Treatment].

               (ii)  the Monthly Subscriber Line Aggregate is greater than or
                     equal to [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] but less than
                     [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] then the Monthly
                     Per Subscriber Line Charge shall be [*Material Omitted and
                     Separately Filed Under an Application for Confidential
                     Treatment];

               (iii) the Monthly Subscriber Line Aggregate is greater than or
                     equal [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] but less than
                     [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] then the Monthly
                     Per Subscriber Line Charge shall be [*Material Omitted and
                     Separately Filed Under an Application for Confidential
                     Treatment];

               (iv)  the Monthly Subscriber Line Aggregate is greater than or
                     equal to [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] but less than
                     [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] then the Monthly
                     Per Subscriber Line Charge shall be [*Material Omitted and
                     Separately Filed Under an Application for Confidential
                     Treatment].

               (v)   the Monthly Subscriber Line Aggregate is greater than or
                     equal [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] but less than
                     [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment] then the Monthly
                     Per Subscriber Line Charge shall be [*Material Omitted and
                     Separately Filed Under an Application for Confidential
                     Treatment].

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Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Exhibit C-2                    Exhibit C-2 - Page 2
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

               (vi) the Monthly Subscriber Line Aggregate is greater than
                    [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment] then the Monthly Per Subscriber
                    Line Charge shall be [*Material Omitted and Separately Filed
                    Under an Application for Confidential Treatment].

          Notwithstanding the foregoing, each of the foregoing Monthly Per
          Subscriber Line Charges may be [*Material Omitted and Separately Filed
          Under an Application for Confidential Treatment] pursuant to Section
          [*Material Omitted and Separately Filed Under an Application for
          Confidential Treatment]. As used herein, [*Material Omitted and
          Separately Filed Under an Application for Confidential
          Treatment] means a [*Material Omitted and Separately Filed Under an
          Application for Confidential Treatment] that is provided by (A)
          [*Material Omitted and Separately Filed Under an Application for
          Confidential Treatment], (B) [*Material Omitted and Separately Filed
          Under an Application for Confidential Treatment], (C) [*Material
          Omitted and Separately Filed Under an Application for Confidential
          Treatment] (D) [*Material Omitted and Separately Filed Under an
          Application for Confidential Treatment] of any such [*Material Omitted
          and Separately Filed Under an Application for Confidential Treatment].

     2.2. Proration of Monthly Per Subscriber Line Charge.
          -----------------------------------------------

          If Customer is able to provide Vendor with information [*Material
          Omitted and Separately Filed Under an Application for Confidential
          Treatment] then Vendor shall [*Material Omitted and Separately Filed
          Under an Application for Confidential Treatment] of the applicable
          Monthly Per Subscriber Line Charge with respect to such [*Material
          Omitted and Separately Filed Under an Application for Confidential
          Treatment] The applicable Monthly Per Subscriber Line Charge with
          respect to [*Material Omitted and Separately Filed Under an
          Application for Confidential Treatment] If Customer is not able to
          provide Vendor with such information, then

          (a)  no later than [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment] days after the end of
               each calendar month, Customer will provide Vendor [*Material
               Omitted and Separately Filed Under an Application for
               Confidential Treatment] the Monthly Per Subscriber Line Charge.
               [*Material Omitted and Separately Filed Under an Application for
               Confidential Treatment] and

          (b)  for each [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment], Customer shall pay the
               applicable Monthly Per Subscriber Line Charge; provided, however,
               that for [*Material Omitted and Separately Filed Under an
               Application for Confidential Treatment] of the applicable Monthly
               Per Subscriber Line Charge,

     2.3. Monthly Aggregate Subscriber Line Charge.
          ----------------------------------------

          (a)  "Monthly Aggregate Subscriber Line Charge" for a calendar month
               shall mean the greater of:

               (i)  [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment] of the applicable Monthly Per
                    Subscriber Line Charge [*Material Omitted and Separately
                    Filed Under an Application for Confidential Treatment] and

               (ii) [*Material Omitted and Separately Filed Under an Application
                    for Confidential Treatment] (A) [*Material Omitted and
                    Separately Filed Under an Application for Confidential
                    Treatment] Monthly Per Subscriber Line Charge set forth in
                    Section [*Material Omitted and Separately Filed Under an
                    Application for Confidential Treatment] (B) [*Material
                    Omitted and Separately Filed Under an Application for
                    Confidential Treatment].

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Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Exhibit C-2                    Exhibit C-2 - Page 3
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

          For example, if (A) [*Material Omitted and Separately Filed Under an
          Application for Confidential Treatment] (B) [*Material Omitted and
          Separately Filed Under an Application for Confidential Treatment]:

               (iii) [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment].

               (iv)  [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment].

               Accordingly, the Monthly Per Subscriber Line Charge [*Material
               Omitted and Separately Filed Under an Application for
               Confidential Treatment].

          (b)  Except with respect to the [*Material Omitted and Separately
               Filed Under an Application for Confidential Treatment]:

               (i)   [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment];

               (ii)  [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment];

               (iii) [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment];

               (iv)  [*Material Omitted and Separately Filed Under an
                     Application for Confidential Treatment].

          (c)  Notwithstanding the foregoing, Vendor will [*Material Omitted and
               Separately Filed Under an Application for Confidential Treatment]
               the Monthly Per Subscriber Line Charge applicable to [*Material
               Omitted and Separately Filed Under an Application for
               Confidential Treatment] Monthly Per Subscriber Line Charge
               [*Material Omitted and Separately Filed Under an Application for
               Confidential Treatment].

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Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Exhibit C-2                    Exhibit C-2 - Page 4
<PAGE>

                       CONFIDENTIAL TREATMENT REQUESTED

                                  SCHEDULE D

                                Other Services

During the Term, Customer will order from Vendor services (excluding Dial-Up
Access Services, Broadband Backhaul Services and Dial-Up Access Services
provided outside of the United States) (such services to be ordered the "Other
Services") such that the aggregate charges paid to Vendor and Vendor's
Affiliates for such Other Services are equal to or greater than [*Material
Omitted and Separately Filed Under an Application for Confidential
Treatment].dollars ($[*Material Omitted and Separately Filed Under an
Application for Confidential Treatment].) (such commitment the "Other Services
Purchase Commitment"); provided, however, that charges payable for such Other
Services ordered or purchased by Customer or a Special Affiliate of Customer
during December 1999 (collectively, the "Pre-Term Private Line Agreements")
shall contribute toward Customer's satisfaction of the Other Services Purchase
Commitment. Any orders or purchases of Other Services shall be subject to terms
and conditions mutually agreed upon by the Parties, which may include terms and
conditions similar to those set forth in the Master Agreement. Any agreement for
Vendor to provide Other Services to Customer that are private line services
(such services collectively the "Private Line Services") shall contain a
most-favored customer provision substantially similar to the one set forth in
Section 8.3(b) of Schedule B. In the event that (i) Customer is offered by a
third party services similar to the Private Line Services at prices and terms
more competitive that those offered by Vendor or Vendor's Affiliates to
Customer, (ii) Customer, in its sole discretion, requests Vendor to provide
Private Line Services at prices and terms at least as favorable to Customer as
such prices and terms offered by such third party, and (iii) Vendor or Vendor's
Affiliates declines to provide Private Line Services at such prices and terms,
then the Other Services Purchase Commitment shall be reduced by the aggregate
charges paid to such third party for such services.

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Network Services Agreement     America Online, Inc./BBN Corporation CONFIDENTIAL
Schedule D                     Schedule D - Page 1