<PAGE>   1

                                                                   EXHIBIT 10.19

                        CONFIDENTIAL TREATMENT REQUESTED

                               PURCHASE AGREEMENT


THIS AGREEMENT is made as of July 23, 1999 by and between ADAPTIVE BROADBAND
CORPORATION ("Adaptive Broadband"), a Delaware corporation with a principal
office at 1143 Borregas Avenue, Sunnyvale, CA 94089, and I(3)S, INC. ("Buyer"),
a Texas corporation with a principal office at 1440 Corporate Drive, Irving, TX
75038.


                                    RECITALS:

A.   Adaptive Broadband is a developer, manufacturer and supplier of wireless
     telecommunications equipment.

B.   Buyer desires to provide wireless communications network services in
     the U.S. ("Territory") for residential non-commercial multiple dwelling
     unit ("MDU") markets ("Markets").

C.   Adaptive Broadband and Buyer each desire for Adaptive Broadband to sell and
     Buyer to purchase such products for use in connection with those services,
     all on the terms and conditions set forth in this Agreement.

                                   PROVISIONS:

NOW, THEREFORE, in consideration of the mutual representations, warranties and
covenants contained in this Agreement, the parties agree as follows:

1.   SCOPE OF AGREEMENT.

     a.   Equipment and Services. Buyer agrees to buy and Adaptive Broadband
          agrees to sell to Buyer the products described in Exhibit A attached
          to this Agreement ("Products") and the services described in Exhibit B
          attached to this Agreement ("Services").

     b.   Purchase Orders. Buyer may issue purchase orders for any Products or
          Services ("Purchase Orders") to Adaptive Broadband via mail or
          facsimile, in form and content acceptable to Adaptive Broadband.
          Purchase orders will be considered accepted by Adaptive Broadband when
          expressly acknowledged and accepted by Adaptive Broadband in writing
          within the term of this Agreement. Subject to the exception in the
          following sentence, the terms and conditions of this Agreement will
          govern the relationship between the parties and each Purchase Order.
          Therefore, each Purchase Order will automatically be deemed to include
          all the terms and provisions of this Agreement, and any contractual
          terms and conditions contained in a Purchase Order or its reverse side
          will not apply and will be null and void, except to the extent that
          Adaptive Broadband expressly and specifically accepts such other or
          additional terms and conditions in writing. Buyer shall provide to
          Adaptive Broadband firm purchase orders 120 days in advance of Buyer's
          intended delivery, which purchase orders will become effective only
          upon written acknowledgment and acceptance by Adaptive Broadband.
          Buyer may make one change in quantity under a given purchase order,
          +/- 20% of the dollar amount under that order, by written notice to
          Adaptive Broadband at least 30 days before the delivery date contained
          in Adaptive Broadband's order acceptance.

2.   PRICING AND PAYMENT.

     a.   Pricing. All prices are FOB Adaptive Broadband's relevant U.S.
          facility or its supplier's dock, as may be specified by Adaptive
          Broadband, and are valid for the term of this Agreement. The first
          quoted prices for Products and Services are set forth in Exhibit A and
          Exhibit B, respectively. For so

                                     Page 1


<PAGE>   2


          long as Buyer is in material compliance with its material obligations
          under this Agreement, the prices set forth in Exhibit A for Products
          will be at least as favorable as those offered by Adaptive Broadband
          to customers purchasing Products in substantially like quantities on
          substantially like delivery schedules.

     b.   Payment. All payments by Buyer will be made to Adaptive Broadband
          pursuant to the payment terms and conditions set forth in Adaptive
          Broadband's Standard Terms and Conditions of Sale, attached to this
          Agreement as Exhibit C.

3.   QUANTITY COMMITMENTS.

     a.   Firm Commitment. Buyer agrees to purchase a minimum of * AB-Access
          units (in any combination of access points and subscriber units)
          during the term of this Agreement in accordance with Exhibit A,
          provided (i) the field trial verification and Acceptance Test
          Procedure described in Section 8 and both Exhibit E and Exhibit F are
          completed and materially satisfied in accordance with their terms,
          (ii) Adaptive Broadband is in material compliance with the material
          provisions of this Agreement, and (iii) Adaptive Broadband receives
          FCC certification for the Products.

     b.   Initial Purchase Order. Buyer will issue a Purchase Order within 30
          days of the effective date of this Agreement for one access point and
          three subscriber units for use in the field trial verification of the
          Product outlined in Exhibit E in accordance with the Acceptance Test
          Procedure and parameters set forth in Exhibit F.


     c.   Forecasts. Each quarter (as specified by Adaptive Broadband from time
          to time), Buyer will provide Adaptive Broadband with a non-binding
          rolling quarterly forecast covering the period of 12 calendar months
          beginning with the quarter in which that forecast is provided. Each
          forecast will specify the number of units of Products (separating
          access points and subscriber units) which Buyer anticipates it will
          purchase during each quarter of that 12-month period.


4.   SOFTWARE LICENSE.

     a.   License. Adaptive Broadband grants to Buyer a royalty-free, perpetual,
          and non-exclusive license to use the Software (defined below) within
          the Territory and Market in connection with the Products and Buyer's
          wireless communications network services. Buyer's right to use the
          Software shall be subject to the terms and conditions set out in
          Exhibit D.

     b.   Sub-License. Adaptive Broadband grants to Buyer a royalty-free,
          perpetual, and non-exclusive license to sub-license the Software to
          Buyer's customers and other parties contracting with Buyer for the
          delivery, of broadband wireless data access, each of which utilizes
          Products in the Territory and Market in connection with Buyer's
          wireless communications network services. When granting to customers
          the right to use Software, Buyer shall incorporate in such
          sub-license terms that offer no less degree of protection to Adaptive
          Broadband's (or its licensor's) interest in the Software as those set
          out in Exhibit D.

     c.   "Software". As used in this Agreement, "Software" means any program in
          machine readable code (howsoever provided to Buyer), and intended to
          be loaded into the memory of a Product's processor unit(s) which
          provides operating instructions and user-related application
          instructions (as well as associated documentation used to describe,
          maintain and use such programs), incorporated in any of the Products
          by Adaptive Broadband or supplied to Buyer by Adaptive Broadband for
          use on or in connection with any of the Products; however, Software
          shall not mean any source code.


                                     Page 2
<PAGE>   3


     d.   Third Party Software. The Products and Software include software which
          is licensed by third parties to Adaptive Broadband ("Third-Party
          Software"). Adaptive Broadband will provide Buyer with a copy of the
          requirements and restrictions of all licenses which apply to existing
          and then future Third-Party Software. Each party ("Licensee") agrees
          to defend, indemnify and hold the other ("Other Party") harmless from
          and against any loss, damages, costs, fees (including reasonable
          attorneys' fees) and expenses awarded against or incurred by the Other
          Party as a result of the Licensee's failure to comply with the
          requirements and restrictions of Third-Party Software licenses and
          sub-licenses applicable to the Licensee pursuant to the terms of the
          relevant license or sublicense, or as a result of the Licensee's
          failure to comply with the reasonable requests of the Other Party in
          the Other Party's efforts to comply with the Third-Party Software
          license or sub-license requirements and restrictions imposed upon it.

5.   SOFTWARE MAINTENANCE.

     a.   Notification. Throughout the term of this Agreement and the first 12
          months thereafter, each party will promptly notify the other of any
          defect or error it becomes aware of in any Product or Software or
          documentation.

     b.   Maintenance. For the 12 months immediately following shipment of
          Product and Software ("Software Maintenance Period"), Adaptive
          Broadband will provide to Buyer, free of charge, an element management
          system and all Software bug fixes which are released by Adaptive
          Broadband and made available to the general public solely as a "bug
          fix." These will be provided to Buyer for Buyer to load into
          previously shipped Products and Adaptive Broadband will provide them
          with subsequently shipped Products. Those bug fixes will be governed
          by the provisions of this agreement as "Software."

     c.   Limitations. Adaptive Broadband has no obligation to correct any
          defect or error in the Software to the extent it arises from any
          improper or unauthorized use or operation of the Software by the Buyer
          or its employees or agents, or the adaptation, modification or
          alteration of any part of the Software without Adaptive Broadband's
          prior consent, or any failure by Buyer to install any corrected
          version or any update or improvement of the Software or documentation
          supplied by Adaptive Broadband.

     d.   Third Party Software. Adaptive Broadband will, during the relevant
          warranty period, be responsible for maintenance and support of any
          Third-Party Software which Buyer may use in conjunction with the
          Software or Products. Thereafter, Adaptive Broadband will quote the
          price and details for extended warranty coverage upon request.

     e.   Updates. Buyer acknowledges that updates may involve the use of new
          versions of Third-Party Software or operating systems. Adaptive
          Broadband shall not be responsible for the cost of any new Third-Party
          Software required by Buyer or any related charges if Buyer decides to
          utilize an update provided by Adaptive Broadband.

     f.   Replacements. Buyer shall upon written request by Adaptive Broadband
          return to Adaptive Broadband the replaced version of any updated
          Software and documentation.

     g.   Hardware Updates. Subject to Exhibit A's provisions regarding
          competitive technology, updated Product hardware may become available
          from time to time and will be supplied to Buyer upon Adaptive
          Broadband's terms.



                                     Page 3


<PAGE>   4


6.   GENERAL TERMS AND CONDITIONS.

     Adaptive Broadband's Standard Terms and Conditions of Sale is attached to
     this Agreement as Exhibit C and is hereby incorporated by reference into
     this Agreement and made a part hereof.

7.   CHANGES, MODIFICATIONS AND ENHANCEMENTS.

     Adaptive Broadband will provide the Product enhancements as and how
     described in Exhibit E attached to this Agreement and, with those
     enhancements, the Products will be covered under the product warranty set
     forth in Exhibit C. Throughout the term of this Agreement, Adaptive
     Broadband will maintain the availability of those enhancements in its
     then current generally available Product (except as otherwise agreed to by
     Adaptive Broadband and Buyer in writing), subject only to materials and
     technology availability. Except as otherwise specifically provided in
     Exhibit E, any changes, modifications, or enhancements of the Products
     requested by Buyer which affects either software or hardware modules
     contained therein will be quoted by Adaptive Broadband separately; no
     change order will be implemented until the parties mutually agree in
     writing to the price for this change. Any changes, modifications, or
     enhancements of the Products made by Adaptive Broadband at its own
     initiative and made a part of its then standard Product will become part
     of the Product without additional charge to Buyer. Any changes,
     modifications, or enhancements of the Products made by Adaptive Broadband
     at its own initiative which are not made a part of its then Standard
     Product but are instead offered as an optional feature or upgrade will be
     available to Buyer at an additional agreed upon price.

8.   ACCEPTANCE TESTING AND FIELD TRIALS.

     a.   Exhibit E contains the details of the field trials procedures and
          parameters applicable to the Products purchased by Buyer, which tests
          will be performed at a Buyer location within the continental United
          States. Exhibit F contains the details of the acceptance test
          procedures, specifications, and parameters applicable to Products
          purchased by Buyer. Adaptive Broadband will give Buyer reasonable
          notice of the date of the test and Buyer will make available all
          staff, materials and facilities which Adaptive Broadband reasonably
          requires for the performance of the test. Buyer may not reject any
          Product which has successfully completed all acceptance tests in
          accordance with Exhibit F and field trials in accordance with Exhibit
          E. If an acceptance test is not successfully completed in accordance
          with Exhibit F, and/or if a field trial is not successfully completed
          in accordance with Exhibit E, then Adaptive Broadband and Buyer will
          mutually agree within the ensuing 10 days on a later date when the
          relevant test shall be repeated and the provisions of the relevant
          exhibit will apply to each repeat test conducted. The date on which
          the field trials are successfully completed in accordance with Exhibit
          E is referred to as the "Trial Completion Date."

     b.   All acceptance tests will be at Buyer's location in Irving, Texas. Any
          inspections or testing beyond that those set forth in Exhibit F
          (including any secondary or follow-up inspections or tests) or which
          otherwise exceed, in scope or duration, those normally provided by
          Adaptive Broadband in like circumstances, will be subject to approval
          by Adaptive Broadband, be at additional cost to Buyer, may be deemed
          by Adaptive Broadband to be an event of force majeure for Adaptive
          Broadband's benefit to the extent they affect Adaptive Broadband's
          and/or Buyer's other obligations hereunder, and Adaptive Broadband may
          impose cancellation or rescheduling charges accordingly.

     c.   Buyer agrees that it will initiate the acceptance tests sets forth in
          Exhibit F within 10 business days after delivery of Adaptive
          Broadband's designated final version of the Product enhancements with
          appropriate network management support, and Buyer will complete those
          acceptance tests within 5 business days thereafter. Buyer agrees that
          it will initiate the field trials set forth in Exhibit E within 10
          business days after the successful completion of the Exhibit F
          acceptance tests, and Buyer will complete those field trials within 90
          days thereafter. Those tests and trials which are not completed




                                     Page 4
<PAGE>   5

          successfully will be repeated as necessary in accordance with the
          provisions of this Agreement including without limitation Section
          8(a). Subject to the foregoing, Buyer will use commercially reasonable
          efforts to promptly, successfully and satisfactorily complete all
          tests and trials, and any and all repeat tests and trials.

9.   DOCUMENTATION.

     Adaptive Broadband will provide to Buyer its standard documentation in
     Adaptive Broadband's standard forms, formats, and quantities based on the
     size and scope of the relevant order. Additional copies, and any changes in
     this documentation required by customization of the Products or software
     changes made in response to Buyer requests will be at an additional charge.

10.  PRE-APPROVAL SHIPMENTS.

     Buyer may desire to have Adaptive Broadband build and ship Products for
     actual use in the Territory and Market without Adaptive Broadband having
     FCC Product certification and/or without Buyer having a license required
     by it as a Product operator, whether from the FCC or other or additional
     licensing and approval authorities.

     a.   In order to induce Adaptive Broadband to do build and ship Products
          for actual use in the Territory and Market without Adaptive Broadband
          having FCC Product certification, Buyer agrees as follows: (i) Buyer
          will assist Adaptive Broadband in any labeling requirements, (ii) If
          the Product does not get all requisite approvals, licensing and
          certification on the first round and without additional input from
          Adaptive Broadband, Buyer will honor Adaptive Broadband's reasonable
          requests regarding the scope of the use of those Products until that
          requisite approval, licensing and certification is secured, (iii) If
          Adaptive Broadband deems it necessary or appropriate by reason of the
          approval and/or licensing process for Products to be returned to
          Adaptive Broadband, whether for modification or replacement, then all
          costs and expenses associated with shipping to Adaptive Broadband and
          back to Buyer, as well as all costs and expenses associated with that
          modification or replacement, will be borne by Buyer, (iv) These and
          any other terms for the premature building and shipping of Products
          are binding upon Buyer but are subject to the prior approval,
          requirements, and business judgment of Adaptive Broadband in each
          instance.

     b.   In order to induce Adaptive Broadband to do build and ship Products
          for actual use in the Territory and Market without Buyer having a
          license required by it as a Product operator, whether from the FCC or
          other or additional licensing and approval authorities, Buyer agrees
          as follows: (i) If Adaptive Broadband deems it necessary or
          appropriate by reason of the approval and/or licensing process for
          Products to be returned to Adaptive Broadband, whether for
          modification or replacement, then all costs and expenses associated
          with shipping to Adaptive Broadband and back to Buyer, as well as all
          costs and expenses associated with that modification or replacement,
          will be borne by Buyer, (ii) If Adaptive Broadband deems it necessary
          or appropriate for Adaptive Broadband to send someone on-site to
          facilitate the licensing and/or approval process, then all costs and
          expenses associate therewith will be borne by Buyer, (iii) Buyer will
          defend, indemnify and hold Adaptive Broadband harmless from and
          against any and all judgments, fines, amounts paid in settlement,
          damages, claims, costs, expenses (including attorneys' fees) and
          liabilities incurred and arising out of or related to the premature
          shipping and use of Products.

11.  CONFIDENTIALITY.

     a.   Definition of Confidential Information: Each party ("Disclosing
          Party") may, either orally, in written form, or otherwise disclose to
          the other party ("Recipient") or the Recipient may otherwise obtain
          the Disclosing Party's confidential information ("Confidential
          Information"). If any of the following




                                     Page 5
<PAGE>   6

          apply to any information, such information shall not be considered as
          Confidential Information: (i) it is or becomes available to the public
          through no wrongful act of the Recipient, (ii) it is already in the
          possession of the Recipient as evidenced by documentation in the
          Recipient's possession, and not subject to any agreement of confidence
          between the parties, (iii) it is received from a third party without
          any restriction known to the Recipient for the benefit of the
          Disclosing Party, or (iv) it is independently developed by the
          Recipient without regard to that Confidential Information disclosed by
          the Disclosing Party.

     b.   Use and Care of Confidential Information: Confidential Information
          disclosed or obtained hereunder during the term of this Agreement
          shall only be used by the Recipient only in the performance of its
          obligations or exercise of its rights under this Agreement, and it
          shall not be disclosed by the Recipient for a period of three (3)
          years from the date of disclosure, except to those employees,
          affiliates, advisors, and consultants of the Recipient who have a need
          to know and an obligation to treat Confidential Information in
          accordance with the provisions of this Agreement. The Recipient may
          disclose the Disclosing Party's Confidential Information pursuant to a
          requirement of a duly empowered government agency or a court of
          competent jurisdiction after due notice and an adequate opportunity to
          intervene is given to the Disclosing Party unless such notice is
          legally prohibited. Notwithstanding the expiration or early
          termination or cancellation of this Agreement, the obligations under
          this Section 12(b) shall survive until they expire in accordance with
          their terms.

     c.   Return of Confidential Information: Upon receipt of a written request
          from the Disclosing Party, the Recipient shall, at the Disclosing
          Party's direction, either return to the Disclosing Party or destroy
          all of the Disclosing Party's Confidential Information and so
          certify in writing.

12.  REPRESENTATIONS, WARRANTIES, AND COVENANTS.

     a.   By Adaptive Broadband. Adaptive Broadband represents and warrants to
          Buyer, and covenants that:

          i.   Adaptive Broadband has all corporate power and authority to enter
               into this Agreement and consummate the transactions contemplated
               hereby; and

          ii.  Adaptive Broadband has all the rights necessary to license the
               rights and to supply the Products to Buyer as provided in this
               Agreement.

          iii. Adaptive Broadband covenants that, for the two year period
               beginning the Trial Completion Date and during that two year
               period for so long as Buyer is and remains in material compliance
               with the material provisions of this Agreement, Adaptive
               Broadband will not sell "AB-Access Product With Data Envelope
               Interface Enhancements" (defined below) with the Functionalities
               (defined below) enabled to either: (A) any company which competes
               with Buyer by providing broadband wireless data access to MDUs
               and which Adaptive Broadband Knows, at the time it accepts the
               relevant purchase order, intends for those Products to be used in
               connection with broadband wireless data access services in MDUs
               in the United States; or (B) any company which Adaptive
               Broadband Knows, at the time it accepts the relevant purchase
               order, will re-sell those Products to companies described in
               subsection 12(a)(iii)(A) immediately above.

               Notwithstanding the foregoing in this Section 12(a)(iii), that
               covenant shall not apply to the sale of AB-Access Product With
               Data Envelope Interface Enhancements with the Functionalities
               enabled to either: (X) any telecommunications service provider
               which at the time it seeks to purchase AB-Access Product With
               Data Envelope Interface Enhancements Products provides
               telecommunications services other than Product services, or (Y)
               any other company not specifically included within the class of
               companies covered by Section 12(a)(iii)(A) or (B).

               As used in this Section 12(a)(iii), Adaptive Broadband "Knows" of
               a fact only if one of its corporate officers has timely evidence
               of the fact, without any duty to investigate. "AB-Access




                                     Page 6
<PAGE>   7

               Product with Data Envelope Interface Enhancements" means a
               Product configured with the following functionalities
               ("Functionalities"):

               For subscriber unit Products:

               o    Pass-through forwarding of all upstream traffic

               o    Isolation of layer 2 data streams for upstream traffic

               For access point Products:

               o    Pass-thru upstream forwarding of all upstream traffic

               o    Layer two learning bridge functionality applied to all
                    downstream traffic

               o    Layer two learning bridge implementation using the
                    multiplexing of a single 1483 bridge mapping multiple ATM
                    PVCs among all learned addresses contained in the layer two
                    bridge table.

          iv.  Adaptive Broadband shall not utilize, in any manner whatsoever
               the corporate names or any trademark or trade name or copyright
               rights belonging to Buyer in connection with any equipment or
               service without the prior written approval of Buyer. This
               requirement of consent will survive the expiration or early
               termination of this Agreement.

          v.   Except as otherwise specifically provided in this Agreement, all
               approvals, permits, and authorizations from all applicable
               parties which are necessary for the performance by Adaptive
               Broadband of its obligations under this Agreement, and in
               furtherance of its purposes set forth in the recitals above, will
               be timely obtained and maintained by Adaptive Broadband at its
               own expense.

          vi.  Adaptive Broadband is free to make this Agreement and the making
               hereof and/or performance hereunder by it or any of its officers,
               directors, employees, contractors, consultants, and agents will
               not violate the legal and/or equitable rights or interests of
               any third party.

     b.   By Buyer. Buyer represents and warrants to Adaptive Broadband and
          covenants that:

          i.   Buyer has all corporate power and authority to enter into this
               Agreement and consummate the transactions contemplated hereby;

          ii.  Buyer shall not utilize, in any manner whatsoever the corporate
               names or any trademark or trade name or copyright rights
               belonging to Adaptive Broadband or other Product manufacturers in
               connection with any equipment or service without the prior
               written approval of Adaptive Broadband or the relevant
               manufacturer. This requirement of consent will survive the
               expiration or early termination of this Agreement. Buyer will
               not contest the validity of any of Adaptive Broadband's or other
               Product manufacturer's patents, trademarks, trade names or
               copyrights used in connection with Products; and

          iii. All approvals, permits, and authorizations from all applicable
               parties which are necessary for the performance by Buyer of its
               obligations under this Agreement, and in furtherance of its
               purposes set forth in the recitals above, will be timely obtained
               and maintained by Buyer at its own expense.

          iv.  Buyer is free to make this Agreement and the making hereof and/or
               performance hereunder by it or any of its officers, directors,
               employees, contractors, consultants, and agents will not violate
               the legal and/or equitable rights or interests of any third
               party.

13.  TERM AND TERMINATION.

     a.   Term. This Agreement will be effective as of the date first written
          above and will continue for the period ending sixty months after the
          Trial Completion Date, subject to earlier termination in accordance
          with this Agreement.





                                     Page 7
<PAGE>   8

     b.   Termination. Adaptive Broadband and Buyer each may by written notice
          to the other terminate this Agreement:

          i.   If a receiver is appointed for either party or its property:

          ii.  If either party becomes insolvent or unable to pay its debts as
               they mature in the ordinary course of business or makes an
               assignment for the benefit of its creditors:

          iii. If any proceedings are commenced by or for either party under
               bankruptcy, insolvency, or debtor's relief law, and those
               proceedings will not be vacated or set aside or stayed within
               ninety (90) days from the date of the commencement thereof:

          iv.  If either party is sequestered by any government authority:

          v.   If either party is liquidated, dissolved, or sells all or
               substantially all of its assets:

          vi.  If either party defaults in the performance of any material term
               or condition of this Agreement and that default continues
               unremedied to the non-defaulting party's satisfaction for a
               period of thirty (30) days after notice of default; provided any
               deviation from the terms of this Agreement which is required in
               order to be in compliance with the applicable laws, rules, or
               regulations of any government or subdivision thereof will not be
               considered a default hereunder:

     c.   Upon Expiration or Termination. Upon expiration or early termination
          of this Agreement for any reason, and notwithstanding that expiration
          or termination:

          i.   All provisions of this Agreement will survive with respect to
               each order accepted by Adaptive Broadband prior to the effective
               date of the expiration or termination until each party's
               obligations with respect to that order is either satisfied or
               waived:

          ii.  Termination of this Agreement shall be without prejudice to the
               rights and remedies of the party which may have accrued to
               either party as at the date of termination.

          iii. Notwithstanding the expiration or early termination of this
               Agreement, Section 11 ("Term and Termination") and the provisions
               of Exhibits C ("Terms and Conditions"), D ("Software License and
               Sub-Licensing"), and F ("Acceptance Testing") as they apply to
               any outstanding Purchase Orders shall remain in full force and
               effect and Adaptive Broadband shall still make available in
               accordance with the terms hereof Services to which Buyer is
               otherwise entitled in respect of Products supplied to Buyer prior
               to the date of termination.

          iv.  Notwithstanding the expiration or early termination of this
               Agreement, Section 12 ("Confidential Information") will survive
               for a period of 3 years after the date of disclosure.


          v.   Buyer will within 30 days after expiration or termination return
               to Adaptive Broadband in (at Buyer's sole cost and expense) (or
               at Adaptive Broadband's request eradicate or destroy): all
               literature, manuals and materials supplied to it by Adaptive
               Broadband and which are in Buyer's possession; all equipment
               provided to it by Adaptive Broadband and which Buyer did not
               purchase, in the condition in which it was sent by Adaptive
               Broadband; all tangible and intangible embodiments of Adaptive
               Broadband intellectual property, including software (except that
               which is in Products purchased by Buyer); all Information covered
               under Section 3.3; and any other items which Adaptive Broadband
               may reasonably request.


14.  MISCELLANEOUS.

     a.  Sole Agreement; Amendment; Waivers. This Agreement (together with its
         Exhibits and their attachments which are hereby incorporated into this
         Agreement by reference and made a part hereof) contains the entire
         understanding between Adaptive Broadband and Buyer with respect to its
         subject matter and supersedes all prior discussions, agreements and
         understandings between them with respect to that subject matter. All
         amendments hereto and all agreements between the parties supplemental
         to this Agreement must be in writing and signed by the parties hereto.
         The waiver by either party of a breach or violation of any provision of
         this Agreement must be in writing and will not operate or be construed
         as a waiver of any subsequent breach or violation.


                                     Page 8


<PAGE>   9


     b.   Independent Contractor. Each party acknowledges and agrees that this
          Agreement establishes an independent contractor relationship and each
          disclaims the existence of any employer/employee relationship or
          partnership or joint venture relationship between them. Neither party
          has authority to act for, represent, or bind the other and neither
          will take or fail to take any action inconsistent with this
          paragraph.

     c.   Liability and Indemnification. (i) Subject to the provisions of
          Sections 5, 7, and 12 of Exhibit C, each party ("Indemnifying Party")
          agrees to indemnify and hold the other party and its successors and
          assigns ("Indemnified Party") harmless from and against any and all
          judgments, fines, amounts paid in settlement, damages, claims, costs,
          expenses (including reasonable attorneys' fees) and liabilities
          actually incurred and arising out of or related to the Indemnifying
          Party's breach or threatened breach of this Agreement or any act or
          omission by any of the Indemnifying Party and its agents, employees,
          successors and assigns. (ii) The extent of Adaptive Broadband's
          liabilities to Buyer are solely and exclusively set forth in
          sections 5, 7, and 12 of Exhibit C. (iii) Neither Adaptive Broadband
          nor Buyer will be liable under this Agreement for any consequential
          damage including loss of clientele, loss of business, loss of data, or
          loss of profits. Neither party will be entitled to an indemnity for
          goodwill or other compensation upon termination of this Agreement at
          any time for any reason.

     d.   Buyer Affiliates. Notwithstanding the provisions of Section 14(d), if
          (i) Buyer is or becomes a party to a definitive written agreement
          with a third party for the delivery of broadband wireless data access
          and that third party can use Products in connection with that
          agreement and the delivery of that access, and (ii) Adaptive Broadband
          and that third party enter into a separate definitive written
          agreement for that third party's purchase of Products for that planned
          use, then each Product purchased by that third party under that
          separate Adaptive Broadband agreement will be credited towards the
          satisfaction of Buyer's quantity purchase obligations under this
          Agreement.

     e.   Severability. If any provision of this Agreement is determined by a
          court of competent jurisdiction to be unenforceable or illegal, then
          it will be deemed removed from the other provisions of this Agreement
          which will remain in effect.

     f.   Headings. Headings in this Agreement are included for convenience only
          and themselves have no force or effect.

     g.   Publicity. Neither party shall issue any press release or make any
          public announcement relating to this Agreement or its subject matter
          without the prior written approval of the other; provided that either
          party may make any public disclosure it believes in good faith is
          required by applicable law or any listing or trading agreement
          concerning its publicly-traded securities (in which case the
          disclosing party will use its best efforts to advise the other party
          prior to making the disclosure).

     h.   Order of Precedence. In the event of conflict between any of the
          provisions of this Agreement, the terms set forth above shall govern
          over Adaptive Broadband's Standard Terms and Conditions.

     i.   Governing Law and Related Matters. Any dispute or controversy between
          the parties regarding or arising out of this Agreement, an Exhibit or
          a purchase order which a party wants to resolve in litigation shall be
          brought by that party as follows:

          i.   If the plaintiff is Adaptive Broadband, then (i) it shall
               adjudicate its claim, and Buyer shall adjudicate any related
               cross-claims and counter-claims, in Dallas County, Texas, the
               jurisdiction, venue, and personal jurisdiction to which, for such
               claim or claims, the parties irrevocably consent; and (ii) for
               those claims, cross-claims and counter-claims, this Agreement,
               the Exhibits




                                     Page 9
<PAGE>   10

               and related purchase orders shall be construed in accordance with
               and governed by the internal laws of the State of Texas without
               reference to conflict of laws principles.

          ii.  If the plaintiff is Buyer, then (i) it shall adjudicate its
               claim, and Adaptive Broadband shall adjudicate any related
               cross-claims and counter-claims, in Santa Clara County,
               California, the jurisdiction, venue, and personal jurisdiction to
               which, for such claim or claims, the parties irrevocably consent;
               and (ii) for those claims, cross-claims and counter-claims, this
               Agreement, the Exhibits and related purchase orders shall be
               construed in accordance with and governed by the internal laws of
               the State of California without reference to conflict of laws
               principles.

          Buyer will observe and comply with all applicable governmental laws,
          rules and regulations. Buyer will promptly indemnify Adaptive
          Broadband for all damages, fines, and related expenses (including
          attorneys' fees) resulting from or arising out of Buyer's violation
          of any such law, rule or regulation or breach of this paragraph.

     j.   Notices. Except as otherwise provided in this Agreement, all notices,
          requests, and other communications under this Agreement will be in
          writing and sent by registered post or facsimile addressed to:

            If to Adaptive Broadband, to:              If to Buyer, to:

               Adaptive Broadband Corporation            I(3)S, Inc.
               1143 Borregas Avenue                      1400 Corporate Drive
               Sunnyvale, CA 94089                       Irving, TX 75038
               Attn: Sr. VP Broadband Systems            Attn: President
               Fax: (408) 732-4244                       Fax: (972) 650-7972


            With a copy to:                            With a copy to:

               Adaptive Broadband Corporation            I(3)S, Inc.
               1143 Borregas Avenue                      1440 Corporate Drive
               Sunnyvale, CA 94089                       Irving, TX 75038
               Attn: General Counsel                     Attn: General Counsel
               Fax: (408)732-4244                        Fax: (972) 650-7972

          Any notice sent by fax shall be deemed to be delivered the next
          working day following confirmed transmission, and any notice sent by
          post shall be deemed to be delivered five working days following the
          date of posting. Either party may change the address under this
          section by giving the other party proper notice.






              [The rest of this page is intentionally left blank.]




                                    Page 10
<PAGE>   11


IN WITNESS WHEREOF, Adaptive Broadband and Buyer each executed and deliver this
Agreement as of the date first written above.

I(3)S, INC.                                  ADAPTIVE BROADBAND CORPORATION


/s/ J. R. PRICE                              /s/ FRED LAWRENCE
------------------------------               ------------------------------
Signature                                    Signature

J. R. Price                                  Fred Lawrence
------------------------------               ------------------------------
Print Name                                   Print Name

CEO/CHAIRMAN                                 CHAIRMAN/CEO
------------------------------               ------------------------------
Title                                        Title

7/23/99                                      7/23/99
------------------------------               ------------------------------
Date                                         Date


                                             Legal Approval:
                                                            --------------------
                                                    Date:
                                                         -----------------------

                                             Finance Approval:
                                                              ------------------
                                                    Date:
                                                         -----------------------


                                TABLE OF EXHIBITS

                    Exhibit A - Products, Pricing, and Commitments

                    Exhibit B - Services and Related Pricing

                    Exhibit C - Adaptive Broadband's Standard Terms and
                                   Conditions of Sale

                    Exhibit D - Software License and Sub-License

                    Exhibit E - Enhancements and Field Trial Verification

                    Exhibit F - Acceptance Test, Procedures and Parameters


                                    Page 11
<PAGE>   12

                                    EXHIBIT A


                       PRODUCTS, PRICING, AND COMMITMENTS


PRODUCTS:    AB-Access UNII point to multi-point radio system (access points and
             subscriber units).
             AB-Access UNII point-to-point radio system (access points and
             subscriber units).

<TABLE>
<CAPTION>
PRICING AND COMMITMENTS:                                   Unit price
------------------------                              --------------------
                                                      subscriber    access
     Time frame               Quantity Commitment*       units      points
     ----------               --------------------    ----------    ------

<S>                           <C>                     <C>           <C>
     0-36 months after              * units                *           *
     Trial Completion Date

     0-60 months after            additional * units       *           *
     Trial Completion Date
</TABLE>


     *Buyer may purchase any combination of Product subscriber units and access
     points so long as in the aggregate it has purchased at least that number of
     total units required of it by the end of the relevant period.


     *Buyer may purchase and Adaptive Broadband will ship up to * units (in any
     combination of subscriber units and access points) through March 31, 2000.
     Buyer may purchase and Adaptive Broadband will ship additional units during
     that time period only upon Adaptive Broadband's prior consent. Subject to
     Buyer's * -unit and cumulative * -unit quantity obligations, there is no
     restriction on the number of units Buyer may purchase after March 31.
     2000."



1.   Notwithstanding anything to the contrary:

     (a)  If Buyer fails to satisfy its *-unit purchase obligation by the end of
          the relevant 36-month period, then with respect to its purchase
          deficiency from * units, Buyer shall pay to Adaptive Broadband a
          non-refundable amount equal to * of the agreed upon purchase price of
          the units it was obligated to but failed to purchase.

     (b)  If buyer fails to satisfy its * -unit purchase obligation by the end
          of the relevant 60-month period, then with respect to its purchase
          deficiency from * . Buyer shall pay to Adaptive Broadband a
          non-refundable amount equal to the difference between (i) * of the
          agreed upon purchase price of the units it was obligated to but failed
          to purchase by the end of that 60-month period, less (ii) the amount
          Buyer paid (if any) pursuant to Section 1(a) of this Exhibit A.

     (c)  If Buyer terminates or cancels this Agreement for any reason prior to
          purchasing * units, then with respect to its purchase deficiency from
          * . Buyer shall pay to Adaptive Broadband a non-refundable amount
          equal to * of the agreed upon purchase price of the units it was
          obligated to but failed to purchase.

     Buyer shall pay these obligations net 30 days after the end of that 36th
     month, net 30 days after the end of that 60th month, and net 30 days after
     that cancellation or termination date, as appropriate.

2.   In any subsequent Product purchase agreement(s) entered into between
     Adaptive Broadband and Buyer, Adaptive Broadband will give Buyer credit for
     the Products purchased by it under this Agreement in



                                    Page 12
<PAGE>   13

     determining the quantity discounts applicable to Buyer for Products
     purchased by it under that other agreement(s).


3.   Throughout the term of this Agreement, Adaptive Broadband agrees to
     maintain current Product technology which is competitive in the wireless
     broadband data access markets as measured on a bit-per-Hz basis,
     dollars-per-bit basis, and the general commercial availability of general
     features and functions in the wireless broadband data access markets. To
     define and satisfy that obligation, every six months throughout the term
     of this Agreement Adaptive Broadband and Buyer shall meet to review Buyer's
     upcoming Product technology preferences and Adaptive Broadband's Product
     development plans.


     If Buyer requests that Adaptive Broadband develop a general Product feature
     or function that is generally commercially available in the wireless
     broadband data access markets, then Adaptive Broadband will adjust its
     Product development schedule accordingly. If Adaptive Broadband at its own
     initiative develops a Product feature or function that is not so generally
     commercially available, then it will be available to Buyer at an
     additional agreed upon price.








                                     Page 13


<PAGE>   14


                                    EXHIBIT B


                          SERVICES AND RELATED PRICING


ENGINEERING SERVICES AND PRICING:

          Adaptive Broadband will provide up to * man-days of engineering and
          integration services to I(3)S, free of charge, during the field trial
          and acceptance test phases contemplated by this Agreement and Exhibit
          E. Thereafter, Adaptive Broadband will provide engineering and
          integration services at the rate of */day/man, plus materials and
          travel, lodging and subsistence expenses.


NON-ENGINEERING, INSTALLATION SUPPORT SERVICES:

          *  /day/man plus materials and travel, lodging and subsistence
             expenses.




                                     Page 14


<PAGE>   15


                                    EXHIBIT C


           ADAPTIVE BROADBAND'S STANDARD TERMS AND CONDITIONS OF SALE


The following are the terms and conditions under which Adaptive Broadband
Corporation ("ADAP") sells products, except as otherwise agreed to by ADAP in
writing:


1.   PRICES AND TAXES. The prices will be those set forth in ADAP's quotation or
     bid valid at the time of order. If a quotation has expired, ADAP reserves
     the right to extend the validity of the quotation or issue a new quotation
     at its discretion. Prices are F.O.B. shipping point (North American orders)
     / EX-WORKS (Incoterms, 1990) ADAP's relevant shipping facility
     (International orders), in U.S. dollars and are exclusive of all taxes,
     tariffs, duties and fees. In addition to all charges and fees due under any
     agreement or order between ADAP and Buyer, Buyer is solely responsible for
     and agrees to pay amounts equal to any taxes, tariffs, duties and fees
     (however designated) and any interest, fines and penalties (collectively,
     "Tax") resulting from or arising out of that agreement or order, exclusive
     of taxes based on ADAP's net income. Without limiting the generality of the
     foregoing, Buyer is solely responsible for and agrees to pay, either
     through the relevant product invoice or a separately issued invoice, all
     sales taxes resulting from or arising out of that agreement or order
     unless, within 30 days after shipment, ADAP receives export documentation
     satisfactory to ADAP evidencing the export of the relevant products out of
     the United States. If a Buyer within the United States wishes to have the
     agreement or order treated as sales tax exempt, ADAP must receive a resale
     or exemption certificate satisfactory to ADAP prior to shipment. Buyer will
     pay on ADAP's behalf any Tax levied upon ADAP or reimburse ADAP for any
     such Tax paid by ADAP. This Section will apply during and after termination
     of any agreement between the parties.

2.   ORDERS. No order submitted by Buyer will be deemed accepted by ADAP unless
     and until confirmed in writing by ADAP's authorized representative. No
     order which has been accepted by ADAP may be canceled by the Buyer except
     with the agreement in writing of ADAP and on terms that the Buyer
     will indemnify ADAP in full against all loss (including loss of profit),
     costs (including the cost of all labor and materials used), damages,
     charges and expenses incurred by ADAP as a result of cancellation
     including, at a minimum, the terms set forth in Section 10 below.

3.   PAYMENT. All payments by Buyer will be made in U.S. dollars in the U.S.
     pursuant to one of the following terms, without offset:

     Option 1: Confirmed. Irrevocable Letter of Credit acceptable to ADAP and
     payable in U.S. dollars at sight upon presentation of documents confirming
     shipment (i.e. Invoice, Packing List, Air Waybill) through any major
     United States state or national bank. Validity must be at least 120 days
     for shipment and 150 days for negotiation of documents: partial shipments
     must be allowed: the Letter of Credit value must state F.O.B. shipping
     point (North American orders) or EX-WORKS (Incoterms, 1990) ADAP's relevant
     shipping facility (International orders). Estimated freight and handling
     charges can be provided upon request. All banking charges are to Buyer's
     account.


     Option 2: 25% down-payment in U.S. dollars at the time of order with the
     balance due two weeks prior to shipment. Wire transfer information: Bank of
     America, 1850 Gateway Blvd., Concord, CA 93420, ABA# 121000358, Acct Name
     Adaptive Broadband Corporation, Acct Number 1233727981. Reference Invoice #
     and PO # and Contract #. By Order Of [Buyer's Name]: or such other wire
     transfer information as ADAP may indicate.


     Option 3: If Buyer continually satisfies ADAP's credit approval process and
     requirements and if ADAP provides Buyer with prior written approval of
     credit terms, then net 3O days after the relevant invoice date.

     If ADAP agrees in writing to Option 3 above or if ADAP agrees in writing to
     different or additional payment terms, then:

     a.   If during the period of performance of an order the financial
          condition of the Buyer is determined by ADAP not to justify the terms
          of payment specified, ADAP may demand that payment be made in
          accordance with one of the two options above.

     b.   ADAP reserves the right to make deliveries in installments, all
          installments to be separately invoiced and paid for by Buyer when due
          per invoice without regard to other scheduled deliveries. If shipments
          are delayed by the Buyer for any reason, payment will become due from
          the date on which ADAP is prepared to make shipment and storage will
          be at Buyer's risk and expense.

     c.   In the event of default in payment by Buyer: (i) ADAP may suspend
          performance of its obligations; (ii) Buyer agrees to pay ADAP's
          standard late charges plus interest on the delinquent payment from the
          due date thereof until such payment and all interest thereon is
          received at the rate of 1 1/2% per month, but not in excess of the
          lawful maximum (which charges and interest are not in lieu of any
          other right ADAP may have for Buyer's breach); and (iii) in the event
          of litigation or collection activity arising out of Buyer's
          non-payment, Buyer will promptly pay the reasonable costs and
          expenses incurred by ADAP, including attorney's fees.

4.   DELIVERY, SECURITY INTEREST, DELAYS. Delivery will be F.O.B. shipping
     point (North American orders)/ EX-WORKS (Incoterms, 1990) ADAP's relevant
     shipping facility (International orders). Freight and handling charges are
     to be either remitted in advance or collected under a confirmed,
     irrevocable Letter of Credit as outlined above. All shipments are subject
     to availability and




                                    Page 15
<PAGE>   16
     all references to dates are references to delivery F.O.B. shipping point
     (North American orders) / EX-WORKS (Incoterms l99O) ADAP's relevant
     shipping facility (International orders). Any dates for delivery quoted by
     ADAP or provided in an accepted order are approximations only and ADAP will
     not liable for delay in shipment for any reason. Title to product transfers
     and Buyer assumes all risk of loss upon delivery of product by ADAP to the
     initial carrier. Insurance will be provided by ADAP upon request and
     collected with freight and handling charges. In the absence of instructions
     to the contrary, ADAP on behalf of Buyer, will select the carrier but will
     not be deemed thereby to assume any liability in connection with the
     shipment nor will the carrier be construed to be an agent of ADAP. Claims
     for loss or damage to products in transit must be made to the carrier and
     not to ADAP. Buyer will be responsible for all storage, nagging, drayage
     and other charges to and at Buyer's site. Buyer hereby grants ADAP a
     security interest in the products and all cash and non-cash proceeds
     thereof as security for all of Buyer's obligations hereunder. Upon request
     by ADAP, Buyer will promptly execute any instrument required to perfect
     such security interest, provided that in any event ADAP is hereby appointed
     Buyer's attorney-in-fact to do all acts which ADAP deems reasonably
     necessary or desirable to perfect and continue to perfect such security
     interest and to protect the collateral. ADAP will not be liable for any
     damages or penalty for delay in delivery or for failure to give notice of
     delay when such delay is due to the elements, acts of God, delays in
     transportation, delay in delivery by ADAP's vendors or any other causes
     beyond the reasonable control of ADAP. The delivery schedule will be
     extended by a period of time equal to the time lost because of such delay.


5. INTELLECTUAL PROPERTY.

     If notified promptly in writing of any action (and all prior claims
     relating thereto) brought against Buyer alleging that Buyer's use or other
     disposition of product infringes a United States patent or copyright or
     trade secret, ADAP will defend such action at its expense and will pay the
     costs and damages awarded against Buyer in such action, provided that ADAP
     will have sole control of and authority with respect to the defense of any
     such action and all negotiations for is settlement or compromise. If a
     final injunction is obtained in such action against Buyer's use of the
     product or if in ADAP's opinion the product is likely to become the subject
     of claim or infringement, ADAP will, at its option and at its expense:
     procure for Buyer the right to continue using the product: or replace or
     modify the same so that they become non-infringing: or accept return of the
     product and refund or credit the amount of the original net purchase price,
     less a reasonable charge for depreciation and damage. ADAP will not have
     any liability to Buyer if the alleged infringement is based upon: (a) use
     or sale of the product in combination with other products or devices which
     are not made by ADAP; (b) use of the product in practicing any process: or
     (c) the furnishing to Buyer of any information, service or other
     assistance. No costs nor expenses will be incurred for the account of ADAP
     without the prior written consent of ADAP. In no event will ADAP's total
     liability to Buyer under or as a result of compliance with the provisions
     of this clause exceed the sum paid to ADAP by Buyer for the allegedly
     infringing product. The foregoing states the entire liability of ADAP with
     respect to alleged infringement of patents and copyrights by the product or
     any part thereof or by its operation. This Section states the entire
     liability of ADAP for any infringement of patent, copyright, trademark,
     trade secret, or other intellectual property rights.

     If notified promptly in writing of any action (and all prior claims
     relating thereto) brought against ADAP alleging that ADAP's use of or
     compliance with Buyer's designs, specifications, or instructions infringes
     a United States patent or copyright or trade secret. Buyer will defend such
     action at its expense and will pay the costs and damages awarded against
     ADAP in such action, provided that Buyer will have sole control of and
     authority with respect to the defense of any such action and all
     negotiations for its settlement or compromise. No costs nor expenses will
     be incurred for the account of Buyer without the prior written consent of
     Buyer. The foregoing states the entire liability of Buyer with respect to
     alleged infringement of patents and copyrights and trade secrets by the
     product or any part thereof or by its operation by reason of ADAP's use of
     or compliance with Buyer's designs, specifications or instructions.

6.   PRODUCT CHANGES. ADAP reserves the right, without prior approval from but
     with notice to Buyer, to make changes to products or their specifications
     (a) which do not materially adversely affect the performance of the product
     or reduce performance below any contract specification: (b) when required
     for purposes of safety: (c) to meet product specifications, or (d) when
     required to conform with any applicable statutory or regulatory
     requirements. ADAP reserves the right to make product improvements without
     incurring any obligation or liability to make the same changes in products
     previously manufactured or purchased. ADAP also reserves the right to
     modify the availability of models in its product lines based on market
     conditions, component availability, and other business considerations: and
     to require that Buyer implement and utilize software upgrades as a
     condition of maintenance contracts and warranty.

7.   WARRANTY

     PRODUCT MANUFACTURED BY ADAP:

     a.   Products manufactured by ADAP are warranted against defects in
          material and workmanship for a period of one (1) year from date of
          delivery as evidenced by ADAP's packing slip or other transportation
          receipt.

     b.   ADAP's sole responsibility under this warranty will be to either
          repair or replace, at its option, any component which fails during the
          applicable warranty period because of a defect in material or
          workmanship, provided Buyer has promptly reported same to ADAP in
          writing. All replaced products and parts will become ADAP's
          property.


     c.   ADAP will honor the warranty at the repair facility designated by
          ADAP. It is Buyer's responsibility to return, at its expense, the
          allegedly defective product to ADAP. Buyer must obtain a Return
          Material Authorization (RMA) number and shipping instructions from
          ADAP prior to returning any product under warranty. Transportation
          charges for the return of the product to Buyer will be paid by ADAP
          within the United States. For all other locations, the warranty
          excludes all costs of shipping,





                                    Page 16
<PAGE>   17

          customs clearance and other related charges. If ADAP determines in
          good faith that the product is not defective within the terms of this
          warranty, Buyer will pay ADAP all costs of handling, transportation
          and repairs at the then prevailing repair rates.

     d.   All the above warranties are contingent upon proper use of the
          product. These warranties will not apply (i) if adjustment, repair, or
          product or parts replacement is required because of accident, unusual
          physical, electrical or electromagnetic stress, neglect, misuse,
          failure of electric power, environmental controls, transportation,
          failure to maintained properly or otherwise in accordance with ADAP
          specifications, or abuses other than ordinary use, (ii) if the
          product has been modified by Buyer or has been repaired or altered
          outside ADAP's repair facility unless ADAP specifically authorizes
          such repairs or alterations in each instance; or (iii) where ADAP
          serial numbers, warranty data or quality assurance decals have been
          removed or altered.

     e.   No person, including any dealer, agent or representative of ADAP is
          authorized to assume for ADAP any other liability on its behalf except
          as set forth herein. If any payment is due ADAP for services performed
          hereunder, it will be subject to the same payment terms as the
          original purchase.

     PRODUCTS MANUFACTURED BY OTHERS:

     For products not manufactured by ADAP, the original manufacturer's or
     licensor's warranty will be assigned to Buyer to the extent permitted by
     the manufacturer or licensor and is in lieu of any other warranty,
     expressed or implied. For warranty information on a specific product, a
     written request should be made to ADAP.

     ALL PRODUCTS:

     THE FOREGOING WARRANTIES AND REMEDIES ARE EXCLUSIVE AND ARE IN LIEU OF ALL
     OTHER EXPRESS OR IMPLIED WARRANTIES, OBLIGATIONS, AND LIABILITIES ON THE
     PART OF ADAP. EXCEPT FOR THE EXPRESS WARRANTIES STATED HEREIN, ADAP
     DISCLAIMS ALL WARRANTIES ON PRODUCTS FURNISHED HEREUNDER. INCLUDING,
     WITHOUT LIMITATION, ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
     FOR A PARTICULAR PURPOSE. ADAP WILL HAVE NO RESPONSIBILITY FOR ANY
     PARTICULAR APPLICATION MADE OF ANY EQUIPMENT. Any description of equipment,
     whether in writing or made orally by ADAP or its agents, specification
     sheets, models, bulletins, drawings, or similar materials used in
     connection with Buyer's order are for the sole purpose of identifying the
     equipment and will not be construed as an express warranty. Any
     suggestions by ADAP or its agents regarding use, application or
     suitability of the equipment will not be construed as an express
     warranty. No warranties may be implied from any course of dealing
     or usage of trade. Buyer agrees that the exclusion of all warranties,
     other than those expressly provided herein, is reasonable.

8.   ACCEPTANCE OF PRODUCTS. Unqualified acceptance of products will occur
     upon delivery, unless ADAP is notified in writing within ten days from
     Buyer's receipt that the products do not meet ADAP's specifications or
     that Buyer is making a claim for shortages or other errors in delivery.
     Failure to give such timely notice constitutes a waiver of all such
     claims by Buyer. ADAP's sole obligation for any non-conforming products
     will be limited to repair or replacement, at ADAP's option, pursuant to
     the provisions of the foregoing warranty clause.

9.   INSTALLATION. In the event ADAP agrees with Buyer to install or perform
     maintenance on any product(s) to be supplied. Buyer will pay ADAP'S then
     current standard charges for such installation or maintenance.

10.  CANCELLATION AND RESCHEDULE CHARGES. In the event Buyer defaults, ADAP may
     decline to make further shipments and/or may terminate Buyer's order
     without affecting ADAP's rights and remedies including, but not limited
     to, any right to cancellation charges and quantity price adjustments. If
     ADAP continues to make shipments after Buyer's default, ADAP's action
     will not constitute a waiver nor affect ADAPs legal remedies. In the
     event Buyer (a) cancels any order or portion thereof with the requisite
     ADAP consent; or (b) fails to meet any obligation hereunder, causing
     cancellation or rescheduling of any order or portion thereof; or (c)
     requests a rescheduling of scheduled product and such request is accepted
     by ADAP. Buyer agrees to pay ADAP cancellation/reschedule charges as a
     percentage of the list price of the canceled/rescheduled product, said
     charges having been agreed upon not as a penalty, but as a result of the
     difficulty of computing actual damages. Such cancellation/rescheduling
     charges may be set by ADAP in its business judgment in each instance. Buyer
     may not cancel or reschedule any order or portion thereof after shipment.


11.  EXPORT. Regardless of any disclosure made by Buyer to ADAP of an ultimate
     destination of the product(s). Buyer will not export, either directly or
     indirectly, any product(s) or non-ADAP equipment incorporating such
     product(s) without first obtaining a license from the U.S. Department
     of Commerce or any other agency or department of the United States
     Government, as required. Buyer will use its best efforts to insure that
     none of the products will reach any country where U.S. laws would forbid
     ADAP to market or distribute the products.


12.  DISCLAIMER AND LIMITATION OF LIABILITY.

     A.   ADAP'S TOTAL LIABILITY IS LIMITED TO THE NET PRICE OF THE PRODUCTS
          SOLD HEREUNDER, EXCLUDING ANY CHARGES STATED SEPARATELY FROM THE
          PRODUCT PRICE ON THE INVOICE. BUYER'S SOLE REMEDY FOR LIABILITY OF ANY
          KIND, INCLUDING NEGLIGENCE, WITH RESPECT TO THE PRODUCTS, SOFTWARE,
          AND DOCUMENTATION FURNISHED HEREUNDER IS LIMITED TO THE REQUEST FOR
          ADAP, AT ADAP'S OPTION, TO REFUND THAT NET PRICE FOR THE ITEMS AND
          MATTERS INVOLVED, EXCEPT THAT IN THE CASE OF A BREACH OF WARRANTY,
          BUYER'S SOLE REMEDY IS TO RETURN THE PRODUCT TO ADAP FOR REPAIR OR
          REPLACEMENT IN ACCORDANCE WITH THE "WARRANTY" SECTION OF THESE TERMS
          AND CONDITIONS.



                                    Page 17
<PAGE>   18

     B.   WITH RESPECT TO SERVICES, ADAP'S LIABILITY FOR ANY SERVICE IS
          LIMITED TO THE RE-PERFORMANCE OF THE SERVICE. ADAP DOES NOT WARRANTY
          PROPOGATION OR PATH PERFORMANCE. ALL SURVEYS ARE ACCURATE AS OF THE
          DATE THE SURVEY WAS CONDUCTED.

     C.   IN NO EVENT WILL ADAP BE LIABLE TO BUYER, OR WILL BUYER BE LIABLE
          TO ADAP, FOR (I) REPROCUREMENT COSTS; (II) INDIRECT, INCIDENTAL,
          SPECIAL, OR CONSEQUENTIAL DAMAGES; (III) ANY DAMAGES WHATSOEVER
          RESULTING FROM LOSS OF USE, DATA OR PROFITS ARISING OUT OF OR IN
          CONNECTION WITH THIS AGREEMENT OR THE USE OR PERFORMANCE OF ADAP
          PRODUCTS, WHETHER IN AN ACTION OF CONTRACT OR TORT, INCLUDING
          NEGLIGENCE AND STRICT LIABILITY, EVEN IF THE OTHER PARTY HAS BEEN
          ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

     D.   NO ACTION, WHETHER IN CONTRACT OR TORT, INCLUDING NEGLIGENCE, ARISING
          OUT OF OR IN CONNECTION WITH THIS AGREEMENT MAY BE BROUGHT BY EITHER
          PARTY MORE THAN EIGHTEEN (18) MONTHS AFTER THE CAUSE OF ACTION HAS
          ACCRUED, EXCEPT THAT AN ACTION FOR NON-PAYMENT MAY BE BROUGHT
          WITHIN EIGHTEEN (18) MONTHS OF THE DATE OF LAST PAYMENT.

13.  GENERAL PROVISIONS.

     a.   The rights and obligations under these terms and conditions may not be
          assigned without ADAP's prior written consent and any attempt to
          do so without such consent will be void.

     b.   Buyer will pay to ADAP all costs, fees and expenses (including
          attorneys' fee) incurred by ADAP in enforcing, or attempting to
          enforce, any of its rights under these terms and conditions or any
          contract of sale between them.

     c.   All rights and remedies, whether conferred hereby or by any other
          instrument or law will be cumulative and may be exercised singularly
          or concurrently. Failure by either party to enforce any contract
          terms will not be deemed a waiver of future enforcement of that nor
          of any other term. If any provisions of this contract are held invalid
          under any applicable law, rule, regulation or treaty, such invalidity
          will not affect other provisions of this contract which can be given
          effect without the invalid provisions and to this end, the
          provisions of this contract are declared to be severable.
          Notwithstanding the above, such invalid provision or clause will be
          construed, to the extent possible, in accordance with the original
          intent of the parties.

     d.   Any typographical, clerical or other error or omission in any sales
          literature, quotation, price list, acceptance of offer, invoice or
          other document or information issued by ADAP will be subject to
          correction without any liability on the part of ADAP.

     e.   Where products include radio frequency communications equipment,
          certain regulations of telecommunications regulatory authorities
          apply. It is the sole responsibility of the Buyer to ensure
          compliance with all such regulations and all other applicable
          laws and rules and to procure and maintain at its own expense any
          relevant license from such regulatory authority to install, operate
          and maintain the equipment.



                                     Page 18


<PAGE>   19


                                    EXHIBIT D


                        SOFTWARE LICENSE AND SUB-LICENSE


Set out below are the terms and conditions of the software license granted by
Adaptive Broadband to Buyer. In sub-licensing software to its customers, Buyer
shall incorporate in such sub-licenses terms which offer no less degree of
protection than those set out below:

1.   The Software and the documentation are unpublished copyright works and may
     be used on any installation with a configuration mentioned in the
     Agreement, provided the Software is in use on only one installation at any
     one time.

2.   Neither the Software nor the documentation may be copied in whole or in
     part, except for backup and archival purposes.

3.   The copyright notices and trademarks contained in the Software, on the data
     medium, and in the documentation as supplied to Buyer must appear on all
     copies made by Buyer.

4.   Save for Buyer's right to grant sub-licenses to its customers in the
     Territory and Market to use the Software in object code form, Buyer may not
     transfer part, download, or in other way make available to others the
     Software and the documentation delivered to it.

5.   Buyer shall not have the right to modify the Software or to create
     derivative works based on the Software, save as provided under applicable
     laws.

6.   No warranty applies if failure of the Software has resulted from misuse or
     misappropriation.

If a new release of the Software contains new functions, and Buyer wants to use
these new functions, the new release shall be subject to a supplementary charge.
No license is granted for any new release until Buyer pays associated
additional fees. Buyer will be responsible for costs of software/hardware
upgrades of equipment supplied by third parties to support such new releases.

Any replacement of the Software will be guaranteed for the remainder of the
original warranty period or 3 months, whichever is longer.




                                    Page 19
<PAGE>   20

                                    EXHIBIT E

                    ENHANCEMENTS AND FIELD TRIAL VERIFICATION
                                   APPENDIX E


            USE OF ADAPTIVE BROADBAND WITHIN I(3)S DATA ENVELOPE(TM)

This attachment is an analysis of how I(3)S can use the Adaptive Broadband
equipment as part of the I(3)S Data Envelope(TM) product architecture for
delivering broadband access to the Internet over forward deployed Ethernet
switches and other in-unit technologies. Below is a link-by-link and
device-by-device description of a property network architecture, detailing what
operations are required and what operations must not be performed along the
path. At the end is a detailed list of required changes to the Adaptive
Broadband product to satisfy the architectural model as well as other security,
configuration and management items.

                                  [FLOW CHART]



                                    Page 20
<PAGE>   21

WORKING FROM THE PC TO THE CPE ROUTER


F    10 Mbps Ethernet
     PCs are attached to the Edge Ethernet Switch via 10 Mb Ethernet.

Edge Ethernet Switch
     Conforming to the requirements of the Data Envelope(TM), the switch does
     not perform any subscriber port (S) to subscriber port (S) switching. All
     traffic (broadcast and unicasts) which enters a subscriber port (S) must be
     switched out the trunk port (T). The Edge Ethernet Switch will function as
     a learning bridge and create a MAC table to identify all MAC addresses out
     each port. Multiple PCs (and MAC addresses) may be attached to a hub on a
     single switch port.

E    10/100 Mbps Ethernet
     The aggregation of traffic from multiple 10 Mbps sources requires a higher
     bandwidth trunk.

Adaptive Broadband Subscriber Unit
     This device must provide a 10/100 Mbps Ethernet interface at the subscriber
     port (S). Any bit presented to S must be sent out T. There is no need to
     perform any MAC layer or IP layer analysis. All traffic must be presented
     to the router, even IP layer peer to peer traffic.

D    25 Mbps Pt-Mpt Wireless

Adaptive Broadband Access Point
     This device must provide a 10/100 Mbps Ethernet interface at the trunk port
     (T). Any bit presented to S must be sent out T. All traffic must be
     presented to the router, even IP layer peer to peer traffic.

C    10/100 Mbps Ethernet

Hub Ethernet Switch
     Conforming to the requirements of the Data Envelope(TM), the switch does
     not perform any subscriber port (S) to subscriber port (S) switching. All
     traffic (broadcast and unicasts) which enters a subscriber port (S) must be
     switched out the trunk port (T). The Hub Ethernet Switch will function as a
     learning bridge and create a MAC table to identify all MAC addresses out
     each port.

B    10/100 Mbps Ethernet



                                    Page 21
<PAGE>   22

Router

     The main element in the Data Envelope(TM), all packets transmitted on the
     property enter the router for processing, accounting, and forwarding. The
     router sees all PCs on the property on the same IP subnet and in the same
     broadcast domain. The router can communicate with all PCs via broadcasts or
     multicasts, which will be replicated as necessary by the Ethernet switches.

A    T1 or greater to POP

WORKING FROM THE CPE ROUTER TO THE PC

A    T1 or greater from POP

Router
     The main element in the Data Envelope(TM), all packets transmitted on the
     property enter the router for processing, accounting, and forwarding. The
     router sees all PCs on the property on the same IP subnet and in the same
     broadcast domain. The router can communicate with all PCs via broadcasts or
     multicasts, which will be replicated as necessary by the Ethernet switches.
     The router can ARP for all PCs by sending a Layer 2 broadcast. The ARP
     reply is only seen by the router.

B    10/100 Mbps Ethernet

Hub Ethernet Switch
     Functioning as a standard Ethernet switch, the switch will flood broadcast
     frames and search its MAC table for the correct port to send an outbound
     unicast packet. At this layer, the switch will have the MAC address of all
     the PCs attached to a downstream switch.

C    10/100 Mbps Ethernet


Adaptive Broadband Access Point
     This device must provide a 10/100 Mbps Ethernet interface at the trunk port
     (T). Any frame presented to t must be sent out s and vice-versa.


D    25 Mbps Pt-Mpt Wireless
     All downstream traffic shares the 25 Mbps data rate.


Adaptive Broadband Subscriber Unit
     This device must provide a 10/100 Mbps Ethernet interface at the subscriber
     port (S). Any frame presented to T must be sent out S.


E    10/100 Mbps Ethernet

Edge Ethernet Switch
     This Ethernet switch will receive all traffic transmitted from the Access
     Point on the Pt-Pt PVC to which its Subscriber Unit is attached. The switch
     will drop all traffic with a




                                    Page 22
<PAGE>   23


     destination MAC address which has not been learned on a subscriber
     port (S). Any traffic with a destination MAC address learned on a
     subscriber port (S) will be forwarded out the appropriate port only.


F    10 Mbps Ethernet
     PCs are attached to the Edge Ethernet Switch via 10 Mb Ethernet.


REQUIRED CHANGES TO ADAPTIVE BROADBAND EQUIPMENT TO MEET I(3)S DATA ENVELOPE(TM)
REQUIREMENTS

Access Point

o    The Access Point (AP) must function at layer 1 and layer 2 only.

o    The AP will support a secure handshake with Subscriber Unit (SU) and/or
     encryption of data to SU

o    The AP will only connect to an SU with the properly configured PVC to
     establish a PVC connection.


o    The AP will function as a Layer 2 MAC Learning Bridge. The AB Access Point
     equipment will function as a Layer 2 MAC learning bridge, providing Pt-Pt
     PVCs to each Subscriber Terminal. The Access Point will correctly implement
     the S to T isolated data flow model correctly, ensuring no S to S
     communication of broadcast or unicast packets. The Access Point will place
     the downstream packet on the correct PVC to be received by only a single
     Subscriber Terminal and forwarded to the correct Ethernet switch.


Subscriber Unit

o    The SU will not function at Layer 3 for subscriber traffic flow.

o    The SU will not learn IP addresses.

o    The SU will not require an IP Subnet per SU.

o    The SU will function at layer 1 and layer 2 only for subscriber traffic
     flow.

o    The SU will support a secure handshake with AP and/or encryption of data to
     the AP.

o    The SU will only connect to an AP with the properly configured PVC to
     establish a PVC connection.



                                    Page 23
<PAGE>   24

                                    EXHIBIT F

                   ACCEPTANCE TEST, PROCEDURES AND PARAMETERS


                                   APPENDIX F

                         ACCEPTANCE TESTING REQUIREMENTS
                                   Revision E

                              General System tests

Item      Description
Number

GS-01     Configuration data is stored locally on each SU and AP device and may
          be power cycled, reboot, and begin forwarding traffic appropriately
          without communication with the network server or network management
          station.

GS-02     Configuration files may be downloaded to an SU or AP device remotely
          via secure RUPEE over TCP/IP (Specifically: PVC configuration, IP
          address assignments, wireless interface configuration, all firmware
          and software).

                               SU - General tests

Item      Description
Number

SU-G-01   The SU builds a bridge table based on Ethernet MAC address only as it
          receives packets in the S and T interface of the SU.

SU-G-02   The bridge table may be viewed via network management, direct SNMP to
          the SU or through a management station proxy.

SU-G-03   The SU maintains counters for received and transmitted MAC layer
          frames and cells.


SU-G-04   The SU will accept all input ethernet traffic on the S interface of
          the device on a standard RJ-45 - 10 Mb half-duplex Ethernet
          connection.


                           SU - Upstream from PC tests

Item      Description
Number

SU-U-01   Valid upstream unicast packets received on an S interface of the SU
          are always forwarded out the T interface of the SU.

SU-U-02   Valid upstream broadcast packets received on an S interface of the SU
          are always forwarded out the T interface of the SU.

SU-U-03   Valid upstream multicast packets received on an S interface of the SU
          are always forwarded out the T interface of the SU.

SU-U-04   The SU does forward packets with source and destination MAC addresses
          on the S interface of the SU out the T interface, and the T interface
          only.

SU-U-05   All packets arriving at the S interface of the SU are forwarded out
          the T interface of the SU.

SU-U-06   No packets arriving at the S interface of the SU are forwarded back
          out the S interface of the SU.



                                    Page 24
<PAGE>   25


                          SU - Downstream to PC tests

Item      Description
Number

SU-D-01   Valid downstream unicast packets received on a T interface of the SU
          are either:
               -Always forwarded out the S interface of the SU (With the
               exception of datagrams terminated within the SU itself)

SU-D-02   Valid downstream broadcast packets received on a T interface of the SU
          are always forwarded out the S interface of the SU.

SU-D-03   Valid downstream multicast packets received on a T interface of the
          SU are always forwarded out the S interface of the SU with the
          exception of some management packets addressed to the SU which are not
          passed on

SU-D-04   The SU does not forward packets with source and destination MAC
          addresses on the T interface of the SU out the S interface; the
          packets are discarded.

SU-D-05   No packets arriving at the T interface of the SU are forwarded back
          out the T interface of the SU.

                               AP - General tests

Item      Description
Number

AP-G-01   The AP builds a bridge table based on Ethernet MAC address only as it
          receives packets in the S and T interface of the SU.

AP-G-02   The bridge table may be viewed via network management, direct SNMP to
          the AP or through a management station proxy.

AP-G-03   The AP maintains counters for received and transmitted MAC layer
          frames and cells.

AP-G-04   The AP will accept all input ethernet traffic on the T interface of
          the device on a standard RJ-45-10 Mb half-duplex Ethernet
          connection.

                           AP - Upstream from PC tests

Item      Description
Number

AP-U-01   Upstream unicast packets received on an S interface of the AP are
          always forwarded out the T interface of the AP with the exception of
          some SU management information packets.

AP-U-02   Upstream broadcast packets received on an S interface of the AP are
          always forwarded out the T interface of the AP.

AP-U-03   Upstream multicast packets received on an S interface of the AP are
          always forwarded out the T interface of the AP with the exception of
          some SU management information packets.

AP-U-04   The AP does forward packets with source and destination MAC addresses
          on the S interface of the AP out the T interface, and the T interface
          only.

AP-U-05   All packets arriving at the S interface of the AP are forwarded out
          the T interface of the AP with the exception of some SU management
          information packets.

AP-U-06   No packets arriving at the S interface of the SU are forwarded back
          out the S interface of the SU.

AP-U-07   All packets forwarded out the T interface of the AP will be forwarded
          out the 10 Mb Ethernet interface identical to the packets received on
          the S interface of the SU; no additional headers from the original PC
          authored Ethernet packet will be presented.



                                    Page 25
<PAGE>   26

                           AP - Downstream to PC tests

Item      Description
Number

AP-D-01   Downstream unicast packets received on a T interface of the AP are
          only forwarded out the S interface of the AP if the destination MAC
          address is located in the bridge table and designates the S interface
          as the interface on which the address was learned

AP-D-02   Downstream broadcast packets received on a T interface of the AP are
          always forwarded out the S interface of the AP.

AP-D-03   Downstream multicast packets received on a T interface of the AP are
          always forwarded out the S interface of the AP with the exception of
          some AP management information packets.

AP-D-04   The AP does not forward packets with source and destination MAC
          addresses on the T interface of the AP out the S interface; the
          packets are discarded.

AP-D-05   No packets arriving at the T interface of the AP are forwarded back
          out the T interface of the AP.

                              AP 1483 bridge tests

Item      Description
Number

AP-BR-01  The 1483 bridge table in any AP must support a minimum of 250
          simultaneous bridge entries.

AP-BR-02  As packets are learned from upstream traffic, the MAC address is
          placed into a bridge table associated with the PVC on which the packet
          was received.

AP-BR-03  Learned MAC addressed must time-out every hour.

AP-BR-04  Entries in an instance of the 1483 bridge tables must capable or being
          cleared via network management interaction

AP-BR-05  Downstream packets will consult the bridge table and forward the
          packet out the S interface on the appropriate PVC.

AP-BR-06  If a PVC to a SU goes down, the bridge table must be cleared.




                                    Page 26
<PAGE>   27

                            Network Management tests

Item      Description
Number

NM-01     A single ADAP NMS will be located in the Irving, TX NOC and can
          support up to 100 ADAP Control Servers.

NM-02     The ADAP NMS will communicate with the ADAP Control Servers via a TCP
          over IP connection.

NM-03     The ADAP Control Server may be configured to only accept network
          management IP connections from a designated subnet and from a discrete
          set of IP addresses. All other network management connections are
          refused and logged.

NM-04     The ADAP Control Server and ADAP NMS connection must be validated
          through a security mechanism, such as shared key.


NM-05     The ADAP Control Server will be located in I3S POPs and communicated
          with on-property APs via a TCP over IP connection.


NM-06     The ADAP Control Server will support up to 1000 simultaneous TCP
          connections to the APs and maintain a response time of less than 2
          seconds.

NM-07     The AP may be configured to only accept network management IP
          connections from a designated subnet and from a discrete set of IP
          addresses. All other network management connections are refused and
          logged.

NM-08     The ADAP Control Server and ADAP NMS connection must be validated
          through a security mechanism, such as shared key.

NM-09     The information exchanged, gathered, etc... between the AP and ADAP
          Control Server can be controlled, minimized, and tailored.

NM-10     The ADAP Control Server will initiate and establish a session based
          UDP over IP connection with each configured AP or SU. UDP packets
          which arrive and violate the session flow will be discarded and
          logged.

NM-11     An AP will forward network management traffic between the ADAP Control
          Server and the designated SU over the specified and designated network
          management PVC configured between the AP and SU.

NM-12     The AP and SU connection must be validated through a security
          mechanism, such as shared key.

NM-13     An AP can be configured to connect to a primary and a secondary ADAP
          Control Server. If the primary is not available after a reasonable
          effort, the AP will connect to the secondary.

NM-14     The IP addresses assigned to AP and SU devices for network management
          may be changed dynamically and through network management.

NM-15     AP and SU devices are assigned a single IP address for network
          management. The IP address may be from the globally non-routable
          ranges. An AP and all subordinate SU devices must share a common IP
          subnet for network management. All devices must support variable
          length subnet masks.



                                    Page 27