Document:

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                                                                    Exhibit 4.11

                                                               Execution Version
                                                               -----------------

                                SEVENTH AMENDMENT

                                       TO

                                FINANCE AGREEMENT

     Seventh Amendment to Finance Agreement (the "Amendment") dated as of
January 16, 2002 by and among OPERADORA UNEFON, S.A. DE C.V., as borrower (the
"Borrower"), TORONTO DOMINION (TEXAS), INC. ("Toronto Dominion"), as collateral
agent (in such capacity, the "Collateral Agent"), and NORTEL NETWORKS LIMITED
(formerly known as Nortel Networks Corporation) ("Nortel Networks"), as
administrative agent (the "Administrative Agent") (pursuant to the Acceptance of
Appointment as Administrative Agent dated June 25, 2000) and lender ("Lender"
and together with the several lenders party to the Finance Agreement (as defined
below) from time to time, the "Lenders").

                                   WITNESSETH:

     WHEREAS, the Borrower, the Administrative Agent, the Collateral Agent and
the Lender have heretofore entered into a Finance Agreement dated as of
September 7, 1999, as amended by the First Amendment to Finance Agreement dated
as of November 15, 1999, the Second Amendment to Finance Agreement dated as of
March 1, 2000, the Third Amendment to Finance Agreement dated as of April 14,
2000, the Fourth Amendment and Waiver dated as of September 18, 2000, the Fifth
Amendment, Consent and Waiver to Finance Agreement dated as of December 13,
2000, and the Sixth Amendment to Finance Agreement dated as of September 20,
2001 (the "Finance Agreement");

     WHEREAS, the Borrower and the Collateral Agent have heretofore entered into
a Closing Memorandum of Understanding dated as of November 15, 1999 (as amended,
the "MOU"), pursuant to which the Borrower was required, among other conditions,
to replace the Stock Pledge Agreement (as defined in the Finance Agreement) for
the Stock Trust Agreement (as defined in the Finance Agreement);

     WHEREAS, all conditions under the MOU, other than the above-described
condition, have been satisfied or otherwise terminated;

     WHEREAS, the Administrative Agent, the Collateral Agent and the Lender have
agreed with the Borrower that the MOU and the above-described remaining
condition contained in the MOU shall be deemed terminated subject to and upon
the effectiveness of this Amendment;

     NOW, THEREFORE, in consideration of the premises, the parties hereto agree
as follows:

<PAGE>

     SECTION 1. Definitions, Ratification, References. Unless otherwise
specifically defined herein, each term used herein that is defined in the
Finance Agreement shall have the meaning assigned to such term in the Finance
Agreement. Each reference to "hereof", "hereunder", "herein" and "hereby" and
each other similar reference and each reference to "this Agreement" and each
other similar reference contained in the Finance Agreement shall from and after
the date of this Amendment refer to the Finance Agreement as amended by this
Amendment.

     SECTION 2. Amendment to Finance Agreement. The parties hereto hereby agree
that the Finance Agreement shall be amended as follows:

     2.1. Stock Trust Agreement.

     Section 6.1(b)(iii) of the Finance Agreement shall be amended by:

          (a) deleting from the sixth line thereof the word "Trust" and
     inserting in its place the word "Pledge".

          (b) inserting in the seventh line thereof, after the word "Agreement,"
     and before the word "and," the following:

               provided that, upon request of the Lenders at any time during the
               term of the Finance Agreement, Borrower shall execute a Stock
               Trust Agreement in substitution of such Stock Pledge Agreement.

     SECTION 3. Termination of MOU. The Borrower and the Collateral Agent hereby
agree that upon the effectiveness of this Amendment, the MOU shall be deemed
terminated and the Borrower shall have no further obligations thereunder.

     SECTION 4. Conditions to Effectiveness. This Amendment shall become
effective as of the date hereof upon the execution and delivery of this
Amendment by the parties hereto.

     SECTION 5. Expenses. The Borrower acknowledges and agrees that in
accordance with Section 4.1 of the Finance Agreement, any expenses incurred by
the Administrative Agent in connection with the preparation of this Amendment
and any other documents prepared in connection herewith and the transactions
contemplated hereby, including reasonable legal fees and out-of-pocket costs and
expenses of outside counsel, shall be fully reimbursed by the Borrower.

     SECTION 6. Representations and Warranties. Each party hereto represents and
warrants (i) that it has the right, power and capacity and is duly authorized
and empowered to enter into, execute, deliver and perform this Amendment and
(ii) that this Amendment and the Finance Agreement as amended by this Amendment
constitute its legal, valid and binding obligations, enforceable against it in
accordance with their respective terms.

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     SECTION 7. No Other Amendments Consents and Waivers. Except as expressly,
amended, modified and supplemented by this Amendment, the provisions of the
Finance Agreement are and shall remain in full force and effect. The
Administrative has not agreed to, and shall not be deemed to have agreed to, any
other amendment, modification, consent or waiver to any of the terms of the
Finance Agreement other than as expressly set forth and agreed upon herein.

     SECTION 8. Governing Law. This Amendment shall be governed by and
interpreted in accordance with the laws of the State of New York (not including
such state's conflict of law provisions).

     SECTION 9. Execution in Counterparts. This Amendment may be executed in any
number of counterparts and each such counterpart shall be deemed to be an
original, but all such counterparts together shall constitute only one
agreement.

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     IN WITNESS WHEREOF, the parties have caused this Amendment to be duly
executed by their duly authorized officers as of the date first above written.

                                         OPERADORA UNEFON, S.A. DE C.V.,
                                         as Borrower

                                         By:  /s/
                                              ----------------------------------
                                         Name:
                                         Title:

                                         By:  /s/
                                              ----------------------------------
                                         Name:
                                         Title:
                                         NORTEL NETWORKS LIMITED,
                                         as Administrative Agent and Lender

                                         By:  /s/ Jorge H. Suarez
                                              ----------------------------------
                                         Name:  Jorge H. Suarez
                                         Title: Attorney-in-Fact

                                         TORONTO DOMINION (TEXAS), INC.,
                                         as Collateral Agent

                                         By:  /s/
                                              ----------------------------------
                                         Name:
                                         Title:<PAGE>

                                                                    Exhibit 4.14

This Supply  Agreement  ("Agreement")  is between  Nortel  Networks  Limited,  a
Canadian  corporation,  and Nortel  Networks de Mexico,  S.A. de C.V., a Mexican
corporation  (collectively,  "Nortel  Networks"),  and Operadora Unefon, S.A. de
C.V., a Mexican corporation  ("Customer" and, together with Nortel Networks, the
"Parties"), and is dated as of June 16, 2003.

                                    RECITALS:

       WHEREAS, the Secretaria de Comunicaciones y Transportes of Mexico granted
to Customer a license to install, operate and exploit a public
telecommunications network authorizing Customer to provide, among other
telecommunications services, wireless PCS telephone services, together with
other licenses to use, develop and exploit radio spectrum frequencies to provide
such telephone service by means of a digital wireless PCS telephone network (the
"Network"), serving each of the nine telecommunication regions of Mexico; and

       WHEREAS, the Parties desire to provide for Nortel Networks to supply
Products and Services in connection with the Network, all on the terms and
conditions set forth herein.

NOW, THEREFORE, in consideration of the mutual promises and covenants set forth
in this Agreement, and for other good and valuable consideration, the receipt
and adequacy of which are hereby acknowledged, the Parties, intending to be
legally bound, hereby agree as follows:

1.     Definitions
       -----------

       1.1    "Provisional Acceptance Tests" means Nortel Networks' applicable
              standard test and verification procedures for the Products or the
              Services (or any portion thereof), as further described in Exhibit
              C hereto.

       1.2    "Business Day" means any day other than Saturday or Sunday or a
              day that is a public holiday in Mexico.

       1.3    "Affiliate" means, with respect to any Party, any corporation,
              partnership, joint venture or other entity of whatever nature that
              controls, is controlled by or is under common control with such
              Party, whether through ownership of voting securities or
              otherwise.

       1.4    "Force Majeure Event" means the occurrence of fire, casualty,
              explosion, lightning, accident, strike, lockout, labor unrest,
              labor dispute (whether or not, in respect of the foregoing
              labor-related matters, the affected Party is in a position to
              settle the matter), war (declared or undeclared), armed conflict,
              civil disturbance, riot, Act of God, delay of common carrier, the

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              enactment, issuance, or application of any law, local by-law,
              regulation, or executive, administrative, or judicial order, acts
              (including delay or failure to act) of any governmental authority,
              or any other similar occurrence beyond the reasonable control of
              the affected Party.

       1.5    "Furnish-only"  means Products  which Customer is responsible  for
              installing.

       1.6    "Hardware" means a Nortel Networks machine or component.

       1.7    "In-Service" means the date on which the earlier of the following
              conditions occurs: (i) the Products are providing communications
              services to Customer or its customers, (ii) Customer places the
              Products into commercial service notwithstanding that there are
              service affecting deficiencies, or (iii) all deficiencies, other
              than non-service affecting deficiencies, have been cured.

       1.8    "Local Nortel Networks Affiliate" means Nortel Networks de Mexico,
              S.A. de C.V.

       1.9    "Products"  means any  Hardware,  Software or Third  Party  Vendor
              Items provided under this Agreement.

       1.10   "Restructuring Agreement" means the Restructuring Agreement, dated
              as of June 16, 2003, entered into among the Parties hereto and
              Codisco Investments LLC.

       1.11   "Services" means the activities to be undertaken by Nortel
              Networks pursuant to an Order, including but not limited to,
              engineering, maintenance, installation, implementation, design,
              consulting, business planning, network planning and analysis.

       1.12   "Site" means a location designated by Customer at which the
              Products are to be installed and the Services are to be performed.

       1.13   "Software" means computer programs in object code form or firmware
              which is owned or licensed by Nortel Networks, its parent or one
              of its subsidiaries or affiliates, and is copyrighted and
              licensed, not sold. Software consists of machine-readable
              instructions, its components, data, audio-visual content (such as
              images, text, recordings or pictures) and related licensed
              materials including all whole or partial copies.

       1.14   "Specifications" means, with respect to Products and/or Services,
              the technical specifications set forth in Exhibit E which describe

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              or explain the standard functional capabilities, performance
              parameters and/or requirements for such Products and/or Services.

       1.15   "Statement of Work" is a document which describes the
              deliverables, estimated timelines, assumptions, responsibility
              matrix, and other relevant terms specific to a project and an
              Order. A Statement of Work shall be governed by the terms and
              conditions of, and constitute a part of, this Agreement. The
              guidelines for developing such Statements of Work are attached as
              Exhibit D hereto.

       1.16   "Taxes" means all federal, state, local, foreign, gross income,
              gross receipts, sales, use, value added, stamp, levies, customs
              duties, franchise, withholding, excise, real or personal property
              taxes, registration charges and all other similar taxes, except
              for any taxes computed upon the net income of Nortel Networks.

       1.17   "Term" means five (5) years, commencing on the Closing Date (as
              defined in the Restructuring Agreement). The Term may be extended
              by written agreement between the Parties.

       1.18   "Third Party Vendor Items" includes "Third Party Hardware" and
              "Third Party Software" and means any non-Nortel Networks hardware
              and/or software supplied to Customer under this Agreement.

       1.19   "Site Equipment List" means the complete list of Products and
              installation materials, if applicable, to be delivered by Nortel
              Networks to a Site to perform an Order with respect to that Site.

       1.20   "days" means calendar days, unless otherwise specified.

2.     Scope of Work; Orders; Change Orders
       ------------------------------------

       2.1    On the terms and subject to the conditions set forth herein, over
              the Term of this Agreement, the Operator agrees to purchase from
              the Vendor, and the Vendor agrees to sell, supply and deliver to
              the Operator, the Products and Services described in this
              Agreement. Each Party shall comply with its obligations as set
              forth in Exhibit H - Responsibility Matrix. All Services to be
              provided in Mexico, including but not limited to the installation
              and the supervision of the installation process, shall be the sole
              responsibility of the Local Nortel Networks Affiliate.

       2.2    Customer may acquire Products or Services by issuing a written
              purchase order, signed by an authorized representative ("Orders").
              All Orders shall reference this Agreement and specify the quantity

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              and price of Products requested, the Nortel Networks quotation or
              proposal number, billing instructions, installation location,
              requested delivery dates, identification of any Services being
              ordered, requested commencement date for Services, any Statement
              of Work, and any other special instructions. All Orders will be
              governed by and cannot alter the terms and conditions of this
              Agreement. In order to be valid, all Orders must be accepted by
              Nortel Networks through a written or electronic communication.
              Nortel Networks reserves the right to charge a fee for
              cancellations of Orders for Products in accordance with the
              following table:

              Days prior to shipment                   Cancellation Fee
              ---------------------                    ----------------
              51 days or more                          No cancellation fee
              36-50 days                               10% of price of the Order
              21-35 days                               15% of price of the Order
              20 days or less                          20% of price of the Order

              Customer shall not cancel an Order after shipment.

              A Statement of Work and any other items which may be necessary for
              the performance of Nortel Networks' obligations hereunder shall be
              mutually agreed upon between the Parties and included as exhibits
              to the Order. Such exhibits shall be deemed incorporated into this
              Agreement by this reference.

       2.3    Customer hereby irrevocably agrees to a US$100,000,000 (one
              hundred million United States dollars) purchase volume commitment
              of Nortel Networks' Products and Services during the Term hereof.
              Furthermore, during the Term hereof Customer shall have an annual
              target volume of US$40,000,000 (forty million United States
              dollars) of Nortel Networks' Products and Services with a minimum
              of US$20,000,000 (twenty million United States dollars), unless
              Customer has already met the purchase volume commitment of
              US$100,000,000 (one hundred million United States dollars).

       2.4    The prices reflected in each Order shall be determined in
              accordance with Exhibit A and are based on the delivery and
              performance schedules as outlined in the Statement of Work and
              specifications incorporated in such Order. Any changes to this
              Agreement or an Order initiated by Customer or Nortel Networks
              after the Closing Date resulting in adjustments to process, job
              schedule, contract price or other requirements thereof may be
              cause for adjustment by Nortel Networks to the prices and to the
              relevant delivery and performance schedules set forth therein, as
              further provided in Exhibit B hereto. Any such adjustment shall be
              detailed in a change order, a form of which is attached to Exhibit
              B ("Change Order"). If the Change Order affects any Products for

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              which Nortel Networks has commenced manufacturing or has shipped
              or any Services for which Nortel Networks has commenced
              performance, the adjustment of the price shall include reasonable,
              documented charges incurred by Nortel Networks related thereto. No
              such changes shall be performed until a Change Order has been
              executed by authorized representatives of the Parties. The Parties
              shall appoint their authorized representatives to execute such
              Change Order.

3. [Intentionally left blank]

4.     Licensed Use of Software
       ------------------------

       4.1.   Upon  delivery of the  Software but subject to payment by Customer
              of the annual  Software  subscription  fees set forth in Exhibit A
              (the "Annual Software  Subscription Fees"), Nortel Networks grants
              Customer a  non-exclusive  license  to use a copy of the  standard
              then-current  MTX Software  base load with all optional  features,
              NBSS  (BSC)   Software  base  load  with  all  optional   features
              (exclusive of any  regulatory  features made  generally  available
              after MTX-11), BTS features (including,  but not limited to, 1XRTT
              voice and data features),  any future capacity enhancements to the
              CDMA elements (including, but not limited to, SMV, EVDO, and EVDV)
              with the Hardware.

              Also, in consideration for, and conditional upon, the payment by
              Customer of the annual Software fee for the PDSN set forth in
              Exhibit A (based upon number of active SSC-II cards and including
              home agent and foreign agent), Nortel Networks grants Customer a
              non-exclusive license to use a copy of the standard then-current
              PDSN Software base load with all optional features (exclusive of
              the optional IP services described in Exhibit A).

              With respect to all current Nortel Networks Products in Customer's
              network as of the Closing Date and Products purchased by Customer
              hereunder and included in Exhibit A, excluding CDMA Products
              described above and Enterprise Products, the price of the Software
              upgrades and features will be no more than US$300,000 per year in
              the aggregate. For the avoidance of doubt, the Parties agree that
              Section 1.1.1, item 12 of Exhibit F (ESSP) provides for some
              Software upgrades at no additional charge.

              Prior to the expiration of the Term, the Parties shall mutually
              agree as to the applicable Annual Software Subscription Fees
              Customer shall pay for its right to use such Software after such
              expiration.

              To the extent Software is furnished for use with designated
              Products or Customer furnished Equipment ("CFE"), Customer is

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              granted a non-exclusive license to use Software only on such
              Products or CFE, as applicable. Software contains trade secrets
              and Customer agrees to treat Software as Information (as defined
              in Section 10).

              Nortel Networks shall upgrade Customer's existing network to
              MTX-10. The project plan for the MTX-10 upgrade will be reasonably
              agreed between the Parties within one week of the Closing Date.

       4.2    Customer will ensure that anyone who uses the Software does so
              only in compliance with the terms of this Agreement. Customer
              shall not: (a) use, copy, modify, transfer or distribute the
              Software except as expressly authorized; (b) reverse assemble,
              reverse compile, reverse engineer or otherwise translate the
              Software; (c) create derivative works or modifications unless
              expressly authorized; or (d) sublicense, rent or lease the
              Software. Licensors of intellectual property to Nortel Networks
              are beneficiaries of this provision. Upon termination or breach of
              the license by Customer or in the event the designated Product or
              CFE is no longer in use in Customer's network, this license
              terminates and Customer will promptly return the Software to
              Nortel Networks or certify its destruction. Nortel Networks may
              audit by remote polling or other reasonable means to determine
              Customer's Software activation or usage levels.

       4.3    With respect to Third Party Software, Customer agrees to abide by
              the terms provided by Nortel Networks with respect to any such
              software. Customer further agrees that the terms contained in any
              Nortel Networks or third party "shrink wrap" or "click" licenses
              shall govern the use of such software. If Nortel Networks and
              Customer agree that delivery of Software is to be made
              electronically via File Transfer Protocol, then delivery of such
              Software by Nortel Networks shall be deemed to have taken place at
              such time as the Software is loaded onto a network server, as
              designated by Nortel Networks, and Customer has been provided with
              appropriate instructions and passwords to enable Customer to begin
              use of such Software.

5.     Charges, Payment and Taxes
       --------------------------

       5.1    (a)    The contract  price for the  Products and Services  will be
                     set forth in Exhibit A hereto.  For  Products  and Services
                     not included in Exhibit A, the Parties will mutually  agree
                     on a customary and  reasonable  price for such Products and
                     Services.  Unless  otherwise  agreed by the  Parties  in an
                     Order,  all  prices  are in  U.S.  dollars,  DDP  (VAT  not
                     included)  Site or Customer  warehouse  (as the case may be
                     based upon  Customer's  designation),  Incoterms  2000. All
                     prices are applicable  solely in Mexico. In the event there
                     is a  change  in the  applicable  importation  taxes,  such
                     change will be reflected as a price adjustment.

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              (b)    With  respect  to Orders  for  Products  for  which  Nortel
                     Networks  is  providing   installation  and   commissioning
                     Services,  such Orders  shall be  invoiced as follows:  (i)
                     fifteen  percent (15%) upon  acceptance of the Order;  (ii)
                     fifty  five  percent  (55%)  upon  shipment;  (iii)  twenty
                     percent  (20%) upon  Provisional  Acceptance;  and (iv) ten
                     percent  (10%) upon Final  Acceptance.  With respect to the
                     payment milestones described in (ii), (iii) and (iv) above,
                     Nortel Networks shall submit pro-forma invoices to Customer
                     ten  (10)  days  prior  to each of the  payment  milestones
                     described above.  Customer will have three Business Days to
                     accept  or  reject  the  pro-forma  invoice.  Invoices  for
                     Products  shall  be  paid  by  Customer  within  three  (3)
                     Business Days of receiving the definitive invoice. Invoices
                     may not be issued  with  respect  to more than one Order or
                     for more than one payment milestone.

              (c)    With respect to Orders for Furnish-Only Products, such
                     Orders shall be invoiced one hundred percent (100%) five
                     (5) days before shipment. Invoices for Products shall be
                     paid by Customer within thirty (30) days of shipment.
                     Nortel Networks shall deliver to Customer a copy of the
                     bill of lading or airway bill within ten (10) days of
                     shipment.

              (d)    Nortel Networks shall invoice Customer thirty percent (30%)
                     of the price of Services other than the extended warranty
                     and support Services described in Exhibit F (ESSP) in
                     advance, and seventy percent (70%) upon completion.
                     Invoices for Services shall be paid by Customer within
                     three (3) Business Days of the invoice receipt.

              (e)    No  later  than  June 30 of every  year  during  the  Term,
                     Customer  shall  issue an  Order  for the  Annual  Software
                     Subscription  Fees and the  Extended  Services  and Support
                     Services  as set forth in Exhibit A, based on the number of
                     Active  Subscribers  in the  network  as of June 20 of that
                     year.  Such  Software  and  Services  shall be  invoiced by
                     Nortel  Networks  in advance as  follows:  five (5) monthly
                     installments  of  US$175,000  starting  July 1,  2003,  one
                     monthly  installment of  US$2,702,000  in December 1, 2003,
                     and  semi-annually   thereafter   starting  June  1,  2004.
                     Invoices  shall  be  paid  by  Customer  within  three  (3)
                     Business  Days  from date of  receipt  of  invoice.  Nortel
                     Networks shall have the right to audit the number of Active
                     Subscribers and Customer shall give reasonable  cooperation
                     to Nortel Networks to carry out such audit.

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                     As used in this Sub-Section (e), "Active Subscribers" means
                     those subscribers listed in the HLR, minus those that have
                     zero balance and cannot make outbound calls.

              (f)    Customer shall pay interest on any late payments at the
                     rate of twelve percent (12%) per annum (1 % per month) or
                     the lesser rate permitted by law. Any such interest shall
                     be invoiced to Customer by the Nortel Networks entity to
                     which such interest is owed.

              (g)    Charges for Software not included in the Annual Software
                     Subscription Fees may be based on extent of use authorized
                     as specified in this Agreement. Customer agrees to pay the
                     charges applicable for any activation or usage beyond the
                     authorized level.

              (h)    Invoices  for Products  shall be issued by Nortel  Networks
                     Limited and invoices  for  Services  shall be issued by the
                     Local Nortel  Networks  Affiliate.  All  invoices  shall be
                     denominated in United States  dollars.  Invoices  issued by
                     the Local Nortel Networks Affiliate may be paid by Customer
                     in United States dollars or in Mexican pesos, at Customer's
                     option,  at the  exchange  rate  published  by the  Bank of
                     Mexico on the date of actual payment.

       5.2    Customer shall be the importer of record and shall promptly pay
              directly to the applicable government authority the Mexican Value
              Added Tax so as to enable Nortel Networks to carry out the
              importation of the Products into Mexico on Customer's behalf.
              Within two weeks of the Closing Date, the Parties shall mutually
              agree on a process for achieving on time customs clearance. Nortel
              Networks shall be responsible for obtaining all export licenses
              and/or complying with other laws applicable to the exportation
              from the country of origin, transshipment if required and
              importation into Mexico of all Products. Nortel Networks shall
              also be responsible for obtaining any import licenses and/or other
              governmental approvals for the importation of the Products into
              Mexico.

       5.3    If withholding of any Tax is required in respect of any payment by
              Customer to Nortel Networks hereunder, Customer shall (i) withhold
              the appropriate amount from such payment, (ii) pay such amount to
              the relevant authorities in accordance with applicable law, and
              (iii) pay Nortel Networks an additional amount such that the net
              amount received by Nortel Networks is the amount Nortel Networks
              would have received in the absence of such withholding.

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       5.4    Customer consents without qualification to the sale and/or
              assignment of account receivables, in whole or in part, including
              all or any part of any associated rights, remedies, and
              obligations, by Nortel Networks without further notice, and
              authorizes the disclosure of this Agreement as necessary to
              facilitate such sale.

       5.5    Nortel Networks reserves the right to reject an Order at Nortel
              Networks' sole discretion, or to withhold shipment of the Products
              or performance of the Services, or any portion thereof, if: (i)
              Customer is in default of its payment obligations hereunder, (ii)
              if Customer is in material breach of its obligations under this
              Agreement; or (iii) if Customer falls under any of the situations
              described in Sub-Sections 16.1(i) through (iv) hereof, and all
              relevant dates for completion shall be adjusted accordingly.

       5.6    Customer hereby irrevocably waives, to the fullest extent
              permitted by law, the right to dispute any invoice submitted by
              Nortel Networks hereunder, if such invoice is not disputed within
              thirty (30) days from invoice receipt. Such dispute must be
              resolved within ninety (90) days from the invoice date. Payment of
              any disputed amounts is due and payable within three (3) Business
              Days of the date of resolution. If the Parties discover that
              Customer has overpaid Nortel Networks, Nortel Networks shall
              return such excess amounts to Customer within three (3) Business
              Days. All other amounts remain due as provided herein.

6. Warranty
   --------

       6.1    Nortel Networks warrants that the Hardware: (i) is free from
              defects in materials and workmanship, and (ii) conforms in all
              material respects to its Specifications. If Hardware does not
              function as warranted during the warranty period, Nortel Networks
              will determine to either: (i) make it do so, or (ii) replace it
              with substantially equivalent Hardware which functions and is as
              warranted. Nortel Networks warrants further that Nortel Networks
              is conveying good title to the Hardware to Customer and such
              transfer is rightful and the Hardware is being delivered to
              Customer free and clear of any lien, claim, charge, security
              interest or other encumbrance.

       6.2    (a) Nortel Networks warrants that when Software is used in the
              specified operating environment it will substantially conform to
              its Specifications. If Software does not function as warranted
              during the warranty period, Nortel Networks will provide a
              suitable fix or workaround or will replace the Software in order
              to permit its continued use and operation, provided the Software
              is within two (2) software release levels of the then current
              Software for CDMA products, or one (1) software release levels of
              the then current Software for other products.

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              (b) The Annual Software Subscription Fees referred to in Section
              4.1 include any new Software releases that become available during
              the Term. In the event that such new Software releases require the
              installation of additional or modified Hardware in order to
              support such Software, it shall be Customer's responsibility to
              acquire and install such additional Hardware, and Nortel Networks
              shall offer to sell to Customer such Hardware and related
              installation Services at reasonable commercial rates consistent
              with this Agreement.

       6.3    Nortel Networks warrants that Services will be performed in a
              professional and workmanlike manner. If Services are not performed
              as warranted and Nortel Networks is notified in writing by
              Customer within thirty (30) days of the date of the non-conforming
              Services, Nortel Networks will re-perform the non-conforming
              Services.

       6.4    The warranty period for Hardware and Software that Nortel Networks
              is installing shall be two (2) years from the earlier of
              Provisional Acceptance or the date such Hardware or Software is
              placed In-Service. The warranty period for Furnish-Only Hardware
              and Software shall be two (2) years from delivery in accordance
              with Section 8.2.

       6.5    No warranty is provided for: (i) supply items normally consumed
              during Product operation; (ii) failures caused by non-Nortel
              Networks products; (iii) failures caused by a Product's inability
              to operate in conjunction with other Customer hardware or
              software; (iv) performance failures resulting from improperly
              performed services not performed by Nortel Networks or one of its
              subcontractors or Affiliates, or Customer's use of unauthorized
              parts or components; or (v) interference or disruption of service
              caused by operation of other radio systems, lightning, motor
              ignition or other similar interferences. In the cases above,
              Nortel Networks will use reasonable efforts to provide without
              delay the recovery service, and then the Parties will agree within
              sixty (60) days on the cause of the problem. Customer shall pay
              for such Service if it is determined that the failure was not
              attributable to Nortel Networks. Warranty will be voided by
              misuse, accident, damage, alteration or modification, failure to
              maintain proper physical or operating environment, or improper
              Customer maintenance.

       6.6    Third Party Vendor Items may carry their own warranties and Nortel
              Networks shall pass through and assign to Customer any such
              warranties to the extent authorized.

       6.7    THESE   WARRANTIES  AND  LIMITATIONS   ARE  CUSTOMER'S   EXCLUSIVE
              WARRANTIES AND SOLE REMEDIES,  AND REPLACE ALL OTHER WARRANTIES OR

                                       10

<PAGE>

              CONDITIONS, EXPRESS OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE
              IMPLIED WARRANTIES OR CONDITIONS OF MERCHANTABILITY AND FITNESS
              FOR A PARTICULAR PURPOSE.

7. Services
   --------

       7.1    Warranty  Services:  During the warranty  period,  Nortel Networks
              ------------------
              provides certain types of warranty Services without charge for
              specified Products to correct Product defects or to bring them up
              to conformance with Nortel Networks published Specifications.
              Customer will obtain Nortel Networks' concurrence prior to
              returning any Product and must reference a return material
              authorization number issued by Nortel Networks on documentation
              accompanying such returned Product. When Customer is required to
              return Hardware to Nortel Networks for warranty service, Customer
              agrees to ship it prepaid and suitably packaged to a location
              Nortel Networks designates. Nortel Networks will return the
              Hardware to Customer at Nortel Networks' expense. Nortel Networks
              is responsible for loss of, or damage to, Hardware while it is (i)
              in Nortel Networks' possession, or (ii) in transit back to
              Customer. Any exchanged Hardware becomes Nortel Networks' property
              and, subject to Section 8 - Title and Risk of Loss, its
              replacement becomes the Customer's property. The replacement
              Hardware may not be new but will be in working order and
              equivalent to the item exchanged. The warranty period for the
              repaired or exchanged Hardware shall be one (1) year from the date
              of repair or replacement. Customer agrees to ensure that exchanged
              Hardware is free of any legal obligations or restrictions that
              prevent its exchange and represents that all returned items are
              genuine and unaltered. Where applicable, before Nortel Networks
              provides warranty services, Customer agrees to: (i) follow the
              problem determination, problem analysis, and warranty services
              request procedures that Nortel Networks provides; (ii) secure all
              program and data contained in Hardware; and (iii) inform Nortel
              Networks of changes in the Hardware's location.

              In addition to the warranty Services described above, Customer may
              purchase post-warranty and other Services to supplement the
              warranty Services, including advanced shipment of replacement
              parts, as further described in Exhibit F - Extended Services and
              Support Plan (ESSP) and pursuant to the terms and conditions set
              forth therein. The warranty service terms and exclusions in
              Section 6 above shall apply to post- and supplemental warranty
              Services.

                                       11

<PAGE>

       7.2    Services  in General:  Customer  agrees to  cooperate  with Nortel
              --------------------
              Networks in the performance by Nortel Networks of the Services,
              including, without limitation, providing Nortel Networks with
              sufficient, free and timely access to facilities, data,
              information and personnel of Customer, and a suitable physical
              environment meeting Nortel Networks' specified requirements to
              permit the timely delivery and installation of Products and/or
              performance of Services, including the recovery by Nortel Networks
              of any tools, diagnostic or test equipment, documentation or other
              items used by Nortel Networks in the performance of the Services.
              In addition, Customer shall be responsible for the accuracy and
              completeness of all data and any other information, including but
              not limited to microwave path studies, RF propagation studies and
              tower location and loading requirements, that it provides or
              causes to be provided to Nortel Networks. Nortel Networks shall
              have no liability for performance degradations resulting from or
              attributable to Customer-provided designs. In the event that there
              are any delays by Customer in fulfilling its responsibilities as
              stated above, or there are errors or inaccuracies in the
              information provided, Nortel Networks shall be entitled to
              appropriate schedule and pricing adjustments, including storage
              fees, subject to the limitations in Section 8.2.

       7.3    Service Personnel: Nortel Networks and Customer are each
              -------------------
              responsible for the supervision, direction, compensation and
              control of their own employees and subcontractors. Nortel Networks
              may subcontract any portion or all of the Services to
              subcontractors selected by Nortel Networks. Neither Party shall
              knowingly solicit to hire employees of the other Party with whom
              it had contact as a result of the performance of the Services for
              a period ending six (6) months after completion of the Services.
              Neither Party shall be precluded from conducting generalized
              searches for employees (and hiring those employees who respond to
              generalized searches) either through the use of search firms or
              advertisements in the media, provided that searches are not
              specifically targeted to employees providing Services.

       7.4    Intellectual Property Rights: Nortel Networks, on behalf of itself
              ----------------------------
              and its subcontractors, reserves all proprietary rights in and to:
              (i) all methodologies, designs, engineering details, and other
              data pertaining to the Services and designs, documentation and
              other work product prepared by Nortel Networks and delivered to
              Customer, (ii) all original works, computer programs and updates
              developed in the course of providing the Services (except
              Customer's developed programs), (iii) discoveries, inventions,
              patents, know-how and techniques arising out of the Services, and
              (iv) any and all products (including software and equipment)
              developed as a result of the Services. The performance by Nortel
              Networks of Services shall not be deemed work for hire. Nortel
              Networks grants to Customer a perpetual, non-exclusive,
              world-wide, paid up license to use, copy and

                                       12

<PAGE>

              modify the designs, documentation and other work product prepared
              by Nortel Networks and delivered to Customer in the performance of
              Services solely for Customer's internal business purposes. It is
              understood between the Parties that Nortel Networks will employ
              its know-how, techniques, concepts, experience and expertise, as
              well as all other intellectual property, including that to which
              it reserves its rights hereunder, to perform services for others
              which are the same as or similar to the Services.

8.     Title and Risk of Loss; Delivery
       --------------------------------

       8.1    Title to Hardware shall pass from Nortel Networks to Customer
              immediately upon arrival to customs broker in Mexico. Risk of loss
              for ordered Hardware shall pass from Nortel Networks to Customer
              upon delivery as described in Section 8.2.

       8.2    (a) Nortel Networks shall deliver the Products to Site in
              accordance with DDP, Incoterms 2000; provided, however, that if
              Customer is not ready to receive such Products, Nortel Networks
              shall keep the Products in its warehouse in Mexico for a maximum
              of three (3) months from the date that the Products are received
              in such warehouse. After such three-month period, Customer shall
              either: (i) accept delivery of such Products on Site; (ii) pay
              Nortel Networks for the warehousing costs of such Products at a
              rate of US$12 per square meter per month; or (iii) accept delivery
              of such Products to Customer's warehouse. In the case of (i) and
              (iii) above, Customer shall have a representative at the Site to
              accept delivery and inventory the Products. If Customer fails to
              do so, Customer shall pay Nortel Networks for the costs associated
              with the subsequent delivery.

              (b) Customer shall accept partial deliveries, except in the cases
              where Customer is performing the installation and commissioning.
              In such case, and notwithstanding the provisions of paragraph (a)
              above, if Nortel Networks does not deliver the Products in full in
              accordance with the Site Inventory List (except for
              installation-related materials), Nortel Networks shall bear the
              costs associated with the subsequent delivery. In the cases where
              special delivery services are required (e.g., cranes, special
              maneuvers, etc.), these will be identified prior to delivery and
              the associated costs shall be borne by Customer.

9.     Installation and Commissioning
       ------------------------------

       9.1    Nortel Networks shall provide Customer a written general
              chronological schedule of the Provisional Acceptance Tests to be
              carried out with respect to the Products and the Services. Nortel
              Networks will notify Customer at least fifteen (15) days in
              advance of the date on which each portion of the

                                       13

<PAGE>

              Products and the Services will be ready for the commencement of
              the Provisional Acceptance Tests to be performed with respect
              thereto. Customer and its representatives shall have the option to
              witness and have unrestricted access to the Provisional Acceptance
              Tests. In the case that Customer chooses not to witness the
              Provisional Acceptance Tests, Nortel Networks will perform said
              tests in Customer's absence. Customer's failure to appear at the
              appointed time and place of performance of the Provisional
              Acceptance Tests pursuant to this Section 9.1 shall not preclude
              Nortel Networks from performing such Provisional Acceptance Tests
              and issuing the applicable Provisional Acceptance Certificate (as
              defined below), upon successful completion thereof. Customer may
              request additional tests, or a repetition of the tests, at its
              sole cost and expense. Customer is responsible for: (i)
              integration and interconnection with and configuration of
              Customer's hardware and/or third party hardware and/or systems;
              and (ii) installation of Furnish-only Products.

       9.2    For purposes of this Agreement, a "Punch List" shall mean each
              list signed by the Parties prepared in conjunction with the
              Provisional Acceptance Tests for the Products and included in the
              related acceptance certificate ("Provisional Acceptance
              Certificate"), which sets forth one or more non service-affecting
              items which have not been fully completed or performed by Nortel
              Networks as of the date of completion of the related Provisional
              Acceptance Test or, subject to Customer's reasonable approval in
              each case, service-affecting items that may require detailed
              analysis as to the appropriate remedy.

       9.3    Upon successful completion of the Provisional Acceptance Tests,
              Nortel Networks shall submit to Customer an acceptance report
              ("Acceptance Report") comprising:

              (i) a certification by Nortel Networks that such Provisional
              Acceptance Tests have been successfully completed, (ii) a Punch
              List with respect to such Provisional Acceptance Test, and (iii)
              copies of all Provisional Acceptance Test results as recorded
              during the execution of such Provisional Acceptance Test.

              Customer will acknowledge such certification by delivering to
              Nortel Networks the Provisional Acceptance Certificate with
              respect to such Products and/or Services within ten (10) business
              days after receipt of the respective Acceptance Report.

       9.4    Provisional Acceptance by Customer shall occur upon the earlier
              of: (i) the date on which the  Customer issues  the  Provisional
              Acceptance Certificate; (ii) if  Customer does not issue the
              Provisional Acceptance Certificate, on

                                       14

<PAGE>

              the eleventh (11th) day after Customer's receipt of the respective
              Acceptance Report; or (iii) one hundred and twenty (120) days from
              shipment of the Products. Notwithstanding (iii) above, Nortel
              Networks shall be obligated to carry out the Provisional
              Acceptance tests.

       9.5    Final Acceptance by Customer shall occur upon the earlier of
              either: (i) the completion of the Punch List; or (ii) one hundred
              and eighty (180) days from shipment of the Products.
              Notwithstanding (ii) above, Nortel Networks shall be obligated to
              correct the Punch List Items.

       9.6    Customer shall not unreasonably withhold provisional acceptance of
              any Product or Service and acceptance shall not be withheld or
              postponed due to: (i) deficiencies or nonconformities of a Product
              or Service resulting from causes not attributable to Nortel
              Networks such as, but not limited to, a material change or
              inaccuracy of information provided by Customer, inadequacy or
              deficiencies of any materials, facilities, or services provided
              directly or indirectly by Customer, or other conditions external
              to the Products or Services that are beyond the limits specified
              in the Specifications; or (ii) deficiencies or shortages with
              respect to the Products or Services that are attributable to
              Nortel Networks but are of a nature that do not prevent operation
              of the Products in a live, commercial environment ("Punch List
              Items"); provided that Nortel Networks, at its expense, agrees to
              correct such Punch List Items within thirty (30) days (or other
              mutually agreed upon time period) after Customer has provisionally
              accepted such Products or Services. Once Nortel Networks has
              corrected the Punch List Items Customer shall not unreasonably
              withhold final acceptance of such Product or Service.

10.    Confidential Information
       ------------------------

       10.1   Confidential information ("Information") means: (i) Software and
              Third Party Software; and (ii) all business, technical, marketing
              and financial information and data that is clearly marked with a
              restrictive legend of the disclosing Party ("Discloser").

       10.2   The Party receiving Information ("Recipient") will use the same
              care and discretion to avoid disclosure, publication or
              dissemination of Information as it uses with its own similar
              information that it does not wish to disclose, publish or
              disseminate. The Recipient may disclose Information only to: (i)
              its employees, attorneys, accountants and agents, and employees,
              attorneys, accountants and agents of its parent, subsidiary and
              affiliated companies or subcontractors who have a need to know for
              purposes of carrying out this Agreement; and (ii) any other party
              with the Discloser's prior written consent. Before disclosure to
              any of the above parties, the Recipient will

                                       15

<PAGE>

              have a written agreement with such party sufficient to require
              that party to treat Information in accordance with this Agreement.

       10.3   The Recipient may disclose Information to the extent required by
              law. However, the Recipient must give the Discloser prompt notice
              and, to the extent reasonably practical, make a reasonable effort
              to obtain a protective order.

       10.4   No obligation of confidentiality applies to any Information that
              the Recipient: (i) already possesses without obligation of
              confidentiality; (ii) develops independently; or (iii) rightfully
              receives without obligations of confidentiality from a third
              party. No obligation of confidentiality applies to any Information
              that is, or becomes, publicly available without breach of this
              Agreement.

       10.5   Each Party's obligations hereunder shall survive for a period of
              five (5) years after receipt of Information from the Discloser,
              except as otherwise mutually agreed upon by the Parties.

       10.6   The Discloser makes no representations or warranties of any nature
              whatsoever with respect to any Information furnished to the
              recipient, including, without limitation, any warranties of
              merchantability or fitness for a particular purpose or against
              infringement.

       10.7   The release of any advertising or other publicity relating to this
              Agreement requires the prior approval of both Parties.

       10.8   Without prejudice to any rights of either Party, upon expiration
              or termination hereof, each Party shall, upon request by the other
              Party, return to the other Party all Information of the other
              Party, including all copies thereof, under its possession or
              control or under the possession or control of its affiliates, or
              destroy or purge its own, and cause the purging of its affiliates'
              systems and files of any such Information and deliver to the other
              Party a written confirmation that such destruction and purging
              have been carried out.

       10.9   The obligations imposed by this Section 10 shall remain in full
              force and effect notwithstanding any expiration or termination of
              this Agreement.

       10.10  Each Party acknowledges that in the event of any breach of this
              Section 10 by a Party, the non-breaching Party (the "Affected
              Party") will suffer irreparable injury not compensable by money
              damages and for which such

                                       16

<PAGE>

              Affected Party will not have an adequate remedy available at law.
              The Affected Party shall be entitled to obtain, without the
              posting of any bond or security, such injunctive or other
              equitable relief to prevent or curtail any such breach, threatened
              or actual. The foregoing shall be in addition to and without
              prejudice to such other rights as the Affected Party may have
              hereunder or under applicable law.

       10.11  Each Party shall promptly notify the other Party if it becomes
              aware of any breach by any person to whom it divulges any
              Information of the other Party and shall give the other Party all
              reasonable assistance in connection with any proceedings which
              such Party may institute against any such person for breach of
              confidentiality.

11.    Patents and Copyrights; Infringement
       ------------------------------------

       11.1   If a third party claims that Nortel Networks Hardware or Software
              provided to Customer under this Agreement infringes such third
              party's patent or copyright, Nortel Networks will defend Customer
              against that claim at Nortel Networks' expense and pay all costs
              and damages that a court finally awards or are agreed in
              settlement, provided that Customer: (a) promptly notifies Nortel
              Networks in writing of the claim, and (b) allows Nortel Networks
              to control, and cooperates with Nortel Networks in, the defense
              and any related settlement negotiations.

       11.2   If such a claim is made or appears likely to be made, Nortel
              Networks agrees to secure the right for Customer to continue to
              use the Hardware or Software, or to modify it, or to replace it
              with equivalent Hardware or Software. If Nortel Networks
              determines that none of these options is reasonably available,
              Customer agrees to return the Hardware or Software to Nortel
              Networks at Nortel Networks' written request. Nortel Networks will
              then give Customer a credit equal to the net purchase price paid
              by Customer. Any such claims against the Customer or liability for
              infringement arising from use of the Hardware or Software
              following a request for return by Nortel Networks are the sole
              responsibility of Customer. This represents Customer's sole and
              exclusive remedy regarding any claim of infringement.

       11.3   Nortel Networks has no obligation regarding any claim based on any
              of the following: (a) anything Customer provides which is
              incorporated into the Hardware or Software; (b) compliance by
              Nortel Networks with the Customer's specifications, designs or
              instructions; (c) the amount of revenues or profits earned or
              other value obtained by the use of a Product by Customer; (d)
              Customer's modification of the Hardware or Software; (e) the
              combination, operation, or use of the Hardware or Software with
              other

                                       17

<PAGE>

              products not provided by Nortel Networks as a system, or the
              combination, operation, or use of the Hardware or Software with
              any product, data, or apparatus that Nortel Networks did not
              provide; (f) the Customer's failure to install or have installed
              changes, revisions or updates as instructed by Nortel Networks; or
              (g) infringement by a Third Party Vendor Item alone, as opposed to
              its combination with Products Nortel Networks provides to Customer
              as a system.

12.    Limitation of Liability
       -----------------------

       12.1   In no event shall Nortel Networks or its agents or suppliers be
              liable to Customer for more than the amount of any actual direct
              damages up to the sum of all amounts paid by Customer hereunder,
              regardless of the cause and whether arising in contract, tort or
              otherwise. This limitation will not apply to claims for damages
              for bodily injury (including death) and damages to real property
              and tangible personal property and fraud for which Nortel Networks
              is legally liable, and payments as set forth in Section 11 -
              Patents and Copyrights.

       12.2   IN NO EVENT SHALL NORTEL NETWORKS OR ITS AGENTS OR SUPPLIERS BE
              LIABLE FOR ANY OF THE FOLLOWING: A) DAMAGES BASED ON ANY THIRD
              PARTY CLAIM, EXCEPT AS EXPRESSLY PROVIDED FOR HEREIN; B) LOSS OF,
              OR DAMAGE TO, CUSTOMER'S RECORDS, FILES OR DATA; OR C) INDIRECT,
              SPECIAL, INCIDENTAL, PUNITIVE, OR CONSEQUENTIAL DAMAGES (INCLUDING
              LOST PROFITS OR LOST SAVINGS), EVEN IF NORTEL NETWORKS IS INFORMED
              OF THEIR POSSIBILITY.

13. [Intentionally left blank]

14. Changes or Substitution of Products; Discontinuance of Products

       14.1   At any time, Nortel Networks may implement changes to the
              Products, modify the Products' designs and Specifications or
              substitute the Products with ones of similar or more recent
              design. The Parties shall mutually agree on the price of such
              changed or substituted Products. Such a change to or substitution
              of the Products provided under this Agreement shall be subject to
              the following requirements: (i) it shall not adversely affect the
              physical or functional interchangeability or the performance
              Specifications of the Products, except as otherwise agreed in
              writing by Customer; (ii) the price for equivalent performance or
              capacity shall not be higher than the price agreed hereunder,
              except as otherwise agreed in writing by Customer; (iii) any
              change or substitution of the Products shall be functionally
              equivalent and compatible with the changed or substituted Product,
              without the need

                                       18

<PAGE>

              for any other adaptations; and (iv) it shall under no
              circumstances either reduce or decrease Nortel Networks' warranty
              obligations set forth in this Agreement.

       14.2   Nortel Networks shall give Customer nine (9) months prior written
              notice in the event that Nortel Networks discontinues the
              manufacturing of any Products sold hereunder. For such
              discontinued Products, Nortel Networks undertakes to continue
              providing spare parts and technical support, including repair of
              any Products (or part thereof) which is sent to Nortel Networks
              for that purpose, for a period of three (3) years after such
              discontinuance. The Parties acknowledge that TN-16X has been
              manufactured discontinued and the last time buy opportunity is
              October 31, 2003.

15. Delayed Shipment of the Products or the Performance of the Services
    -------------------------------------------------------------------

       15.1   Except as provided in Section 8.2, if Customer notifies Nortel
              Networks less than thirty (30) days prior to the scheduled
              delivery date of the Products (or if the Products have been
              manufactured per the agreed upon schedule) that Customer does not
              wish to take delivery thereof at the scheduled time or that a Site
              is not available to receive such Products, or if Customer fails to
              take delivery of such Products upon their arrival at the
              applicable Site, Nortel Networks shall have the right to place the
              Products in storage and Customer shall bear all costs of
              demurrage, restocking, warehousing, reloading, transporting,
              off-loading, and other associated costs incurred by Nortel
              Networks. All such costs shall be paid in full within thirty (30)
              days of Customer's receipt of Nortel Networks' commercial invoice
              therefor.

       15.2   If Customer notifies Nortel Networks less than twenty one (21)
              days prior to the scheduled performance date of the Services that
              Customer does not wish Nortel Networks to perform such Services at
              the scheduled time or that the Site is not available for the
              performance of such Services, Nortel Networks shall have the right
              to delay the performance of the Services and Customer shall bear
              all associated out of pocket travel and other costs incurred by
              Nortel Networks. All such costs shall be paid in full within
              thirty (30) days of Customer's receipt of Nortel Networks'
              commercial invoice therefor.

       15.3   Site facilities and physical specifications of equipment
              (including shelters, fiber cabling, power, etc.) provided by
              Customer for use with the Products sold hereunder must meet Nortel
              Networks' installation and environmental Specifications. Any
              required upgrades will be at Customer's expense.

                                       19

<PAGE>

16.    Term; Termination; Survival
       ---------------------------

       16.1   This Agreement is effective from the Closing Date and shall
              continue in effect thereafter during the Term, unless otherwise
              terminated in accordance herewith.

       16.2   Without prejudice to any rights and remedies provided for
              hereunder, either Party hereto may terminate this Agreement,
              effective immediately, upon written notice to any other Party,
              upon the occurrence of any of the following events or conditions:
              (i) the other Party applies for or consents to the appointment of,
              or the taking of possession by a receiver, custodian, trustee or
              liquidator of itself or of all or a substantial part of its
              property, (ii) the other Party makes a general assignment for the
              benefit of its creditors, (iii) the other Party commences a
              voluntary proceeding under the bankruptcy, insolvency or similar
              laws relating to relief from creditors generally, (iv) the other
              Party fails to contest in a timely or appropriate manner, or
              acquiesces in writing to, any petition filed against it in an
              involuntary proceeding under the bankruptcy, insolvency or similar
              laws relating to relief from creditors generally, or any
              application for the appointment of a receiver, custodian, trustee,
              or liquidator of itself or of all or a substantial part of its
              property or its liquidation, reorganization, dissolution or
              winding-up, or (v) the other Party is in material breach of this
              Agreement. In addition, and without prejudice to any rights and
              remedies provided for hereunder, Nortel Networks may terminate
              this Agreement, effective immediately, upon written notice to
              Customer, if Customer fails to make payment in accordance with the
              terms and conditions hereof, which failure continues for a period
              of ninety (90) days after written notice to Customer.

       16.3   The respective obligations of each Party pursuant to this
              Agreement that by their nature would continue beyond the
              termination, cancellation, or expiration hereof shall survive
              termination, cancellation, or expiration hereof. The warranty
              obligations in Section 6 shall survive with respect to Products
              which Customer has paid in full. Furthermore, the provisions of
              Exhibit F hereto (ESSP) shall survive as long as Customer is
              paying all applicable Annual Software Subscription Fees referred
              to in Section 4.1 hereof.

                                       20

<PAGE>

17.    Manuals and Documentation
       -------------------------

       17.1   "Manuals and Documentation" consist of documents which describe in
              detail the engineering, installation, maintenance, repair and
              operation of Products. Manuals and Documentation shall be provided
              in the English language. Nortel Networks shall ship electronic
              documentation containing the applicable Manuals and Documentation
              to Customer with the initial delivery of a system of Products to
              Customer. Customer may order additional copies of available
              Documentation at Nortel Networks' then applicable prices.

       17.2   Customer may use and reproduce the Manuals and Documentation in
              paper format for purposes of engineering, installing, maintaining,
              repairing and operating the Products, subject to the limitations
              regarding Information set forth in Section 10. Reproduction shall
              include the copyright or similar proprietary notices. Customer is
              responsible for ensuring proper versions of documentation are
              printed and distributed. During the Term, Nortel Networks shall,
              at no additional charge to Customer, make available to Customer
              upon request, electronic files with updates, revisions and
              corrections of such Manuals and Documentation.

18.    Assignment
       ----------

       18.1   Each Party agrees not to assign or otherwise transfer this
              Agreement or its rights under it, or delegate its obligations,
              without the other Party's prior written consent, and any attempt
              to do so is void. Notwithstanding the foregoing, each Party may
              assign or otherwise transfer this Agreement or its rights under
              it, or delegate its obligations, in whole or in part, to any of
              its Affiliates by providing written notice to the other Party, it
              being understood that such assigning Party shall remain fully
              liable hereunder notwithstanding such assignment.

19.    Export; Compliance with Laws
       ----------------------------

       19.1   Customer agrees that it will not export Products procured
              hereunder from Mexico without Nortel Networks' prior written
              consent. Customer represents and warrants that it is buying
              Products and/or Services for its own internal use and not for
              resale. Customer agrees to comply with all applicable laws
              relating to this Agreement, including all applicable export and
              import laws and regulations.

20.    Severability
       ------------

       20.1   In the event that any provision of this Agreement or portions
              thereof are held to be invalid or unenforceable, the remainder of
              this Agreement will remain in full force and effect.

                                       21

<PAGE>

21.    Complete Agreement; Statement of Work
       -------------------------------------

       21.1   The terms and conditions of this Agreement form the complete and
              exclusive agreement between Customer and Nortel Networks and
              replaces any prior oral or written proposals, Statements of Work
              or communications regarding the subject matter thereof. In the
              event of a conflict between this Agreement and a Statement of
              Work, the terms of the Agreement shall prevail. Any changes to
              this Agreement must be made by mutual agreement in writing. All of
              Customer's rights and all of Nortel Networks' obligations are
              valid only in Mexico.

22.    Governing Law
       -------------

       22.1   The laws of the State of New York, including its provisions of the
              Uniform Commercial Code, govern this Agreement, exclusive of their
              conflict of laws provisions, and this Agreement shall be construed
              in accordance with such laws of the State of New York; and nothing
              in this Agreement affects any statutory rights of consumers that
              cannot be waived or limited by contract. The United Nations
              Convention on the International Sale of Goods shall not apply to
              or govern this Agreement.

23.    Informal Dispute Resolution
       ---------------------------

       23.1   Prior to the initiation of any arbitration proceeding pursuant to
              Section 24, but without prejudice to the immediate application of
              the provisions of Section 16.1, in the event any controversy,
              claim, dispute, difference or misunderstanding arises out of or
              relates to this Agreement, any term or condition hereof, any of
              the work to be performed hereunder or in connection herewith, the
              Customer's Project Manager and the Nortel Networks Project Manager
              shall meet and negotiate in good faith in an attempt to amicably
              resolve such controversy, claim, dispute, difference or
              misunderstanding in writing.

       23.2   The Project Managers shall meet for this purpose within ten (10)
              Business Days, or such other time period mutually agreed to by the
              Parties, after such controversy, claim, dispute, difference or
              misunderstanding arises. If the Parties are unable to resolve the
              controversy, claim, dispute, difference or misunderstanding
              through good faith negotiations within such ten (10) Business Day
              period (or such other agreed-to time period), each Party shall,
              within five (5) Business Days after the expiration of such period,
              prepare a written position statement which summarizes the
              unresolved issues and such Party's proposed resolution. Such
              position statement shall be delivered by Nortel Networks to the
              Customer's Chief Technical Officer

                                       22

<PAGE>

              and by the Customer to the Nortel Networks' corresponding officer
              or representative for resolution within (5) Business Days, or such
              other time period mutually agreed to by the Parties.

24. Agreement to Resolve Disputes by Arbitration
    --------------------------------------------

       24.1   Any dispute, controversy or claim arising out of or relating to
              this Agreement, or breach, termination or invalidity thereof,
              shall be settled by arbitration, to be initiated by either Party
              by notifying the other Party in writing, and conducted in the
              English language (provided, however, that documents originally
              prepared in the Spanish language may be admitted in evidence
              without the need for translation) and in accordance with the
              International Arbitration Rules of the American Arbitration
              Association (the "AAA"). At the request of either Party, a
              stenographic transcript of the testimony and proceedings will be
              taken and the arbitrators will base their decision upon the record
              and briefs (including, at the option of the Parties, post-hearing
              briefs) of the Parties.

       24.2   The arbitration shall be conducted by a panel composed of three
              (3) arbitrators. One arbitrator shall be appointed by Nortel
              Networks, and one arbitrator shall be appointed by the Customer,
              in each case within thirty (30) Business Days after the date of
              delivery of the notice requesting arbitration by the Party
              initiating the arbitration to the other Party. The third
              arbitrator shall be appointed by the first two arbitrators within
              fifteen (15) Business Days after the later of the dates of
              appointment of the first two arbitrators. If any Party fails to
              appoint an arbitrator within the thirty Business Day period, or if
              the first two arbitrators fail to agree on the appointment of a
              third arbitrator within the fifteen Business Day period, then the
              arbitrator to be appointed shall be appointed by the AAA. The
              third arbitrator shall not be a citizen or resident of Mexico or
              Canada but may be a citizen or resident of the United States of
              America. Each arbitrator shall be fluent in English.

       24.3   The arbitration proceeding, including the making of the award,
              shall take place in the Borough of Manhattan, City and State of
              New York, United States of America, and the award or the
              arbitrator shall be final and binding upon the parties and may be
              entered in any court of competent jurisdiction.

       24.4   All aspects relating to the Parties' agreement to resolve disputes
              by arbitration set forth in this Section 24, including without
              limitation the validity and enforceability of such agreement to
              arbitrate, the conduct of the arbitration proceeding and the
              recognition and enforcement of any arbitral award in the United
              States of America, shall be governed by the United States Federal
              Arbitration Act, Title 9, United States Code ss.ss. 1 et seq., as

                                       23

<PAGE>

              amended from time to time, to the exclusion of any state or
              municipal laws. The Parties shall consent to the jurisdiction of
              the United States District Court for the Southern District of New
              York for purposes of the foregoing sentence; provided, however,
              that if for any reason said court shall lack subject matter
              jurisdiction, the Parties shall consent to the jurisdiction of the
              Supreme Court of the State of New York, County of New York, for
              such purposes. The Federal Rules of Evidence shall be used as
              non-binding guidelines for the admission of evidence, and
              reasonable discovery, including depositions, shall be permitted,
              only in the event that the International Arbitration Rules of the
              American Arbitration Association are insufficient in this respect.
              Discovery and evidentiary issues shall be decided by the
              arbitrators.

       24.5   Each Party shall pay for the services and expenses of the
              arbitrator appointed by it, its witnesses and attorneys. All other
              fees and expenses incurred in connection with the arbitration
              (including the fees and expenses of the AAA and the cost of the
              services and expenses of the arbitrator appointed by the two
              arbitrators appointed by the Parties or by the AAA) shall be paid
              in equal part by the Parties, unless the award shall specify a
              different division of said fees and expenses.

25.    Waiver of Jury Trial
       --------------------

       25.1   EACH PARTY IRREVOCABLY WAIVES ANY AND ALL RIGHT TO TRIAL BY JURY
              IN ANY LEGAL PROCEEDING ARISING OUT OF, OR RELATING TO, THIS
              AGREEMENT OR THE TRANSACTIONS CONTEMPLATED HEREIN, INCLUDING ANY
              ORDER ISSUED AND ACCEPTED HEREUNDER.

26.    Exhibits; Order of Precedence
       -----------------------------

       26.1   The following Exhibits are part of this Agreement:

              Exhibit A - Prices

              Exhibit B - Change Order Procedures and Form of Change Order
              Exhibit C - Acceptance Testing Exhibit D - Guidelines for
              Statement of Work Exhibit E - Specifications Exhibit F - Extended
              Services and Support Plan (ESSP) Exhibit G - Other Deliverables
              Exhibit H - Responsibility Matrix Exhibit I - IS-41P Description
              Exhibit J - Authorized Third Party Vendors

                                       24

<PAGE>

       26.2   In the event of a conflict between the body of this Agreement and
              one of its Exhibits, the former shall prevail.

27.    Force Majeure
       -------------

       27.1   Notwithstanding anything in this Agreement to the contrary, if the
              supply of the Products or the performance of the Services by
              Nortel Networks, or any portion thereof, or the performance of any
              other obligation hereunder by any Party is prevented, delayed,
              interfered with, or interrupted by reason of a Force Majeure
              Event, such prevention, delay, interference, or interruption shall
              be deemed not to be a default pursuant to this Agreement and the
              time or times for such performance or supply hereunder shall be
              extended by the period or periods same is so prevented, delayed,
              interfered with, or interrupted. The foregoing shall apply even
              though any such cause exists or is foreseeable as of the date
              hereof. Neither Party shall be required to change its usual
              business practices or methods or to assume or incur other than its
              usual costs or expenses in order to mitigate, avoid, or eliminate
              any Force Majeure Event or to reduce the period of any resulting
              delay. Each Party shall notify the other Parties of any delay or
              failure excused by this Section 26 and shall specify the revised
              performance date as soon as practicable. Nothing contained in this
              Section 26 shall affect any obligation of Customer to make any
              payment when due in accordance with this Agreement.

28.    Notices
       -------

       28.1   All notices pursuant to this Agreement will be in writing and
              deemed given when delivered in person, by certified mail or
              courier service, or by facsimile. Notices to Customer shall be
              sent to:

              Operadora Unefon, S.A. de C.V.
              Periferico Sur 4119
              Col. Fuentes del Pedregal
              14141 Mexico, D.F.
              Attention: Chief Operations Officer
              Fax: (+5255) 8582-5097

              With a copy to:

              Operadora Unefon, S.A. de C.V.
              Periferico Sur 4119
              Col. Fuentes del Pedregal
              14141 Mexico, D.F.
              Attention: Chief Executive Officer
              Fax: (+5255) 8582-5079

                                       25

<PAGE>

              Notices to Nortel Networks shall be sent to:

              Nortel Networks (CALA) Inc.
              1500 Concord Terrace
              Sunrise, Florida 33323-2815
              Attention: Senior Counsel
              Fax: (+1-954) 851-8900

              With a copy to:

              Nortel Networks de Mexico, S.A. de C.V.
              Insurgentes Sur 1605, Piso 30
              Col. San Jose Insurgentes
              03900 Mexico, D.F.
              Attention: President
              Fax: (+5255) 5480-2195

29.    Backwards Compatibility

       29.1   "Backwards Compatibility" or "Backwards Compatible" means that any
              referenced prior Software revision level or levels of the
              applicable Software or any referenced prior Hardware revision
              level or levels of the applicable Hardware, as the case may be,
              remains fully functional in accordance with and up to the
              performance and capacity levels to which it was performing
              immediately prior to any such enhancement and/or revision after
              the integration with the succeeding Software revision level or
              Hardware revision level, as the case may be, and that after such
              integration such prior Software revision level or Hardware
              revision level loses no functionality and such succeeding Software
              revision level or Hardware revision level fully works and operates
              with all such functionalities of such prior Software revision
              level or Hardware revision level.

       29.2   In addition to the warranties contained in Section 6 of this
              Agreement, Nortel Networks represents and warrants that each
              Software revision level during the Term of this Agreement will be
              Backwards Compatible with all existing in-service Products and
              with the last two (2) Software revision levels made available to
              the Customer by Nortel Networks. So long as the Customer has opted
              to deploy any one of the last two (2) consecutive Software
              revision levels prior to the current Software revision level, the
              Customer will not be required to purchase more than one Software
              revision level of the Software to achieve and have its then
              in-service Hardware and Software perform all of the functionality
              and features of the most current

                                       26

<PAGE>

              Software revision level of the Software and to maintain Backwards
              Compatibility; provided that the Customer shall deploy each major
              Software release. In the event that Software supplied by Nortel
              Networks at any time does not provide Backwards Compatibility as
              required by this Section 29.2, then Nortel Networks shall provide,
              without charge to Customer, the Software upgrades of the Software
              and otherwise take such steps as may be necessary to achieve
              Backwards Compatibility.

30.    Expenses
       --------

       30.1   Each Party shall bear its own expenses incurred in connection with
              the preparation and negotiation of this Agreement and any other
              documents required to effect the transactions contemplated hereby.

31. Relationship of the Parties
    ---------------------------

       31.1   All performance by either Party under this Agreement shall be
              performed as an independent contractor or client (as the case may
              be) and not as an agent of the other Party, and neither Party
              shall be, nor represent itself to be, the employee, agent,
              representative, partner or joint venturer of the other. Neither
              Party shall have the right or authority to incur or assume an
              obligation on behalf of or in the name of the other Party or to
              otherwise act on behalf of the other. The performing Party shall
              be responsible for its employees' compliance with all applicable
              laws while performing under this Agreement. This Agreement shall
              not be construed to create any relationship, contractual or
              otherwise, between Customer and any of Nortel Networks'
              subcontractors.

       31.2   The liability of Nortel Networks Limited and of Nortel Networks de
              Mexico, S.A. de C.V. hereunder shall be joint and several.

32     Headings
       --------

       32.1   The headings given to the Sections and Exhibits herein are
              inserted only for convenience and are in no way to be construed as
              part of this Agreement or as a limitation of the scope of the
              particular Section or Exhibit to which the title refers.

33. Waiver
    ------

       33.1   Unless otherwise specifically provided by the terms of this
              Agreement, no delay or failure to exercise a right resulting from
              any breach of this Agreement shall impair such right or shall be
              construed to be a waiver thereof, but such right may be exercised
              from time to time as may be

                                       27

<PAGE>

              deemed expedient. If any representation, warranty or covenant
              contained in this Agreement is breached by either Party and
              thereafter waived by the other Party, such waiver shall be limited
              to the particular breach so waived and not be deemed to waive any
              other breach under this Agreement.

34. [Intentionally left blank]

35.    Counterparts
       ------------

35.1   This Agreement may be executed by the Parties on any number of separate
       counterparts, and all such counterparts taken together shall be deemed to
       constitute one and the same instrument. Execution of this Agreement may
       be made by facsimile signature which, for all purposes, shall be deemed
       to be an original signature.

36.    Project Managers
       ----------------

       36.1   The Customer shall appoint a project manager (the "Customer's
              Project Manager") with overall authority and responsibility for
              representing the Customer in overseeing the Nortel Networks'
              Products and Services hereunder. With respect to all matters
              related to the Products, the Customer's Project Manager shall be
              authorized to act as the primary point of contact for Nortel
              Networks in dealing with the Customer on all aspects of the
              Products and Services and to issue all consents or approvals and
              make all requests related thereto on behalf of the Customer. The
              Customer's Project Manager shall be responsible for managing the
              performance of the activities for which the Customer is
              responsible, and of reporting the status thereof and the problems
              relating thereto (together with recommended solutions thereto, if
              any) to the Vendor Project Manager, in order for the Vendor
              Project Manager to track the status of such activities with
              respect to the Statement of Work.

       36.2   The Vendor shall appoint a project manager (the "Vendor Project
              Manager") to coordinate Nortel Networks' overall delivery of the
              Products and Services and liaise with the Customer's Project
              Manager. With respect to all matters related to the Products and
              Services, the Vendor Project Manager shall be authorized to act as
              the primary point of contact for the Customer in dealing with
              Nortel Networks on all aspects of the Products and Services and to
              issue all consents or approvals and make all requests on behalf of
              Nortel Networks.

                                       28

<PAGE>

37.    Insurance
       ---------

       37.1   During the Term of this Agreement each Party shall maintain
              all-risk insurance policies covering its own acts against the
              personal liability to, and property damage or loss sustained by,
              any third parties. Such insurance shall be maintained with
              reputable insurance companies.

       37.2   Each Party shall obtain and maintain, or require each of its
              Subcontractors to obtain and maintain, during the time any such
              Subcontractors are engaged in providing Products and Services
              hereunder, adequate insurance coverage consistent with the
              requirements of Section 37.1 (provided that the maintenance of any
              such Subcontractor insurance will not relieve the Party of its
              other obligations pursuant to Section 37.1).

38.    Use of Subcontractors
       ---------------------

       38.1   Unless the parties agree otherwise, in the event any portion of
              the Services are subcontracted or assigned, Nortel Networks shall
              be solely and personally responsible, as between Customer and
              Nortel Networks, for the due performance by, and the liabilities
              to Customer of, such authorized subcontractors of all the
              applicable terms and conditions of this Agreement. Regardless of
              whether or not Nortel Networks obtains approval from Customer of a
              subcontractor or whether Nortel Networks uses a subcontractor
              recommended by Customer, such approval, use or recommendation will
              in no way increase Nortel Networks' rights or diminish Nortel
              Networks' liabilities to Customer with respect to this Agreement,
              and shall not, under any circumstances: (i) give rise to any claim
              by such subcontractor against Customer; (ii) create any
              contractual obligation by Customer to the subcontractor; (iii)
              give rise to a waiver by Customer of its rights to reject any
              Service; or (iv) in any way release Nortel Networks from being
              responsible to Customer for the due performance by Nortel
              Networks, whether directly or through such subcontractor, of all
              the applicable terms and conditions of this Agreement.

       38.2   In selecting subcontractors as permitted hereunder, Nortel
              Networks shall ensure that all Services provided by any such
              subcontractors meet the specifications and standards agreed to in
              this Agreement.

       38.3   The terms of this Agreement shall in all events be binding upon
              Nortel Networks regardless of and without regard to the existence
              of any inconsistent terms in any agreement between Nortel Networks
              and any subcontractor, and without regard to the fact that
              Customer may have had notice, directly or indirectly, of any such
              inconsistent term.

       38.4   Customer shall have the right to reasonably object to the use of a
              certain subcontractor by Nortel Networks, in which case Nortel
              Networks shall

                                       29

<PAGE>

              refrain from using such subcontractor and the project
              implementation schedule shall be adjusted day for day.

39. IS-41P
    ------

       39.1   Nortel Networks hereby grants to Customer (and shall grant to
              Authorized Third Party Vendors) a non-exclusive and fully-paid
              license to use the IS-41P Software (the "Software License") for as
              long as this Agreement (or any replacement agreement, extension or
              renewal thereof) is in full force and effect and in Customer's
              Network only; provided, however, that in the case of any such
              Authorized Third Party Vendor, such license shall be subject to
              terms and conditions to be agreed upon between the Vendor and such
              Authorized Third Party Vendor. The Software License includes the
              full present and future IS-41P feature set, triggers and messages,
              not limited to pre-paid, deployed within Nortel Networks'
              portfolio (MTX and MSC), e.g., multiple SMS functionality, as more
              fully described in Exhibit I hereto. If in the future any of such
              features, triggers or messages is no longer part of IS-41P, the
              Software License shall nevertheless continue to be in effect with
              respect to such feature, trigger or message. The Software License
              shall otherwise be governed by the provisions of Section 4 hereof,
              except that it shall not be limited by number of devices and/or
              subscribers. Customer shall pay for any enhancement or
              modification of the IS-41P Software which may be requested by
              Customer such amounts as may be mutually agreed.

       39.2   As used in this Section, "Authorized Third Party Vendors" means,
              without limitation, vendors of telecommunications equipment which
              do not design, develop or supply access network elements that
              enable cellular telephony service based on IS-41 or ANSI 41
              protocols, such as cellular switches, BTSs and BSCs. A list of
              agreed upon Authorized Third Party Vendors is attached as Exhibit
              J hereto. Any Authorized Third Party Vendors which are not listed
              in Exhibit J hereto must be agreed between the Parties in
              accordance with the criteria contained in this definition. Nortel
              Networks shall have the right to withdraw its approval of any
              Authorized Third Party Vendor, whether or not included in Exhibit
              J hereto, if such Authorized Third Party Vendor is acquired by a
              vendor of telecommunications equipment which designs, develops or
              supplies access network elements that enable cellular telephony
              service based on IS-41 or ANSI 41 protocols, such as cellular
              switches, BTSs and BSCs; provided, however, that Nortel Networks'
              exercise of such right shall not affect any hardware or software
              which has already been purchased by Customer from any third party
              vendor or which has been integrated into the Network.

                                       30

<PAGE>

40.    Other Deliverables
       ------------------

       40.1   Nortel Networks shall perform the activities described in Exhibit
              G hereto at no cost to Customer.

41. Extended Services and Support Plan (ESSP)
    -----------------------------------------

       41.1   With respect to the Nortel Networks' Products purchased from
              Nortel Networks by Customer and whose warranty has expired or
              terminated, regardless of whether purchased under this Agreement
              or another agreement with Nortel Networks or an Affiliate thereof,
              Nortel Networks shall provide technical assistance support
              services as further described in Exhibit F.

              [The remainder of this page intentionally left blank]

                                       31

<PAGE>

IN WITNESS WHEREOF, the Parties have executed this Agreement as of the date
first above written.

OPERADORA UNEFON, S.A. DE C.V.

By:     /s/ Adrian Steckel

        -----------------------
Name:   Adrian Steckel

        -----------------------
Title:  Chief Operating Officer

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

NORTEL NETWORKS LIMITED

By:     /s/ James Kinney

        -----------------------
Name:   James Kinney
Title:  Attorney-in-Fact

NORTEL NETWORKS DE MEXICO, S.A. DE C.V.

By:     /s/ Gerardo Bravo

        -----------------------
Name:   Gerardo Bravo

        -----------------------
Title: Attorney-in-Fact

                                       32

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