Document:

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                                                                    EXHIBIT 10.4

                                MASTER AGREEMENT

THIS Master Agreement (the "Agreement") is made as of the 1st day of August,
2001, between ITC DeltaCom Communications, Inc., a corporation organized and
existing under the laws of the state of Alabama with offices at 55 Marietta
Street, Atlanta, Georgia 30303 (hereinafter "ITCD"), and Weblink Wireless, Inc.
a corporation organized and existing under the laws of the state of Delaware
with offices at 3333 Lee Parkway, Suite 100, Dallas, Texas 75219 (hereinafter
the "Customer"). This Agreement shall become effective August 1, 2001 (the
"Effective Date").

WHEREAS, on May 23, 2001, Customer filed for protection under Chapter 11 of the
United States Bankruptcy Code, in the U.S. Bankruptcy Court, Northern District
of Texas, Dallas Division (Case No. 01-34275-SAP-11) ("Bankruptcy Case"); and

WHEREAS, the effectiveness of this Agreement is subject to the following
conditions precedent: (i) Customer shall have filed with the Bankruptcy Court a
motion to approve WebLink's assumption of the Agreement ("WebLink's Assumption
Motion") that is in form and substance satisfactory to the parties; and (ii) an
order shall have be entered by the Bankruptcy Court authorizing WebLink to enter
into this Agreement and approving WebLink's Assumption Motion ("Assumption
Order"); and

WHEREAS, the Amended and Restated Master Agreement expires by its terms on July
31, 2001 and the parties desire to enter into a new agreement with respect to
ITCD's provision of and Customer's purchase of satellite uplinking, equipment
and software maintenance and network management services as set forth herein and
as approved by the Bankruptcy Court order.

NOW THEREFORE, the Parties, intending to be legally bound, further agree that as
of the Effective Date, the Original Agreement, as amended by the Amendments, is
hereby amended and restated to read in its entirety as follows:

ARTICLE 1. CONTRACT DOCUMENTS

This Agreement is comprised of terms and conditions and related attachments that
define specific equipment and services to be provided. The following attachments
hereto, are made a part hereof and incorporated by reference herein:

   Appendix A   - Technical Specifications
   Appendix B   - Price and Rates
   Appendix C   - Equipment and Services Order
   Appendix D   - Network Management Service
   Appendix E   - Equipment Maintenance Service
   Appendix F   - Software Maintenance Services
   Appendix G   - Service Level Agreement

ARTICLE 2. DEFINITIONS

For the purpose of this Agreement, including the Appendices attached hereto,
the following words and expressions shall have the following meanings:

(a)  "Affiliates" means, with respect to any person, any other persons directly
     or indirectly controlling, controlled by or under common control (i.e., the
     power to direct affairs by reason of ownership of voting stock, by contract
     or otherwise) with such person and any director, officer or employee of
     such person.

(b)  "Alternate Hub" means the Customer site located at Spacecom Systems, 6723
     West Steger Road, Monee, Illinois 60449, which Customer may use to access
     its satellite capacity to run its network for load-sharing with (subject to
     the provisions of Article 11) or failure of the Primary Hub.

(c)  "Equipment" means equipment purchased by Customer hereunder, as listed in
     Appendix B hereto, including VSATs and associated hub hardware and remote
     site hardware including embedded Software licensed to Customer pursuant to
     this Agreement.

(d)  "NECAM" means NEC America, Inc.

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(e)  "POCSAG" means Post Office Code Standardization Advisory Group.

(f)  "Primary Hub" means ITCD's primary hub location in Atlanta, Georgia,
     through which Customer accesses satellite capacity for Customer's network.

(g)  "SAC" means Satellite Access Controller.

(h)  "Services" means any services to be provided by ITCD hereunder, including
     network management services, uplinking services, and Equipment and Software
     maintenance services.

(i)  "SNMS" means Satellite Network Management System.

(j)  "Software" means third party software provided by ITCD's vendors that is
     used in connection with the Equipment, or otherwise used by ITCD to provide
     Services pursuant to this Agreement.

(k)  "VNI" means VSAT Network Infrastructure comprised of equipment, software
     and technologies of ITCD used to transmit and receive data to the connected
     equipment of Customer as described in Appendix A.

(l)  "VSAT" means Very Small Aperture satellite Terminal and includes an outdoor
     unit ("ODU"), an indoor unit ("IDU"), an antenna and associated
     interfacility ("IFL") cabling.

ARTICLE 3. PRICES

3.1  For all Equipment, Software and Services provided within the continental
     United States, prices listed in Appendix B are firm for the Term of this
     Agreement.

3.2  The charges specified herein do not include any amounts for occupation,
     sales, use, property, privilege, license, excise or similar taxes, fees or
     assessments which may be levied by any governmental or regulatory agency on
     this Agreement, the Equipment, Software, or Services provided or the
     payments made hereunder. Any such taxes or charges shall be paid directly
     by Customer to the taxing authority, if legally permitted. Otherwise, if
     required to be paid by ITCD, the amount shall be reimbursed to ITCD by the
     Customer promptly upon demand therefor. Upon request, the Customer shall
     provide ITCD with tax exemption certificates, if applicable, or evidence of
     tax payments, if made by Customer.

3.3  The charges specified herein do not include any amounts for freight,
     shipping, handling or insurance, all of which shall be invoiced to Customer
     and paid pursuant to Article 6 hereof.

ARTICLE 4. ORDERING METHOD

4.1  The Software licenses and Services itemized on Appendix C represent
     Customer's current requirements, which may change from time to time to
     reflect Customer's needs. The quantity of services and licenses listed in
     Appendix C are hereby ordered by Customer in accordance with the terms set
     forth herein. Customer may add, relocate, or remove VSATs from its network,
     however, Customer agrees to maintain and to pay for the Services described
     on Appendix C for a minimum of 2000 activated VSATs ("Minimum Commitment")
     during each month of the Term of this Agreement. Customer agrees to pay for
     such Equipment, Software and Services in accordance with the terms of this
     Agreement. Customer must give written notice to ITCD of its intent to
     delete any VSAT no later than thirty (30) days prior to the Customer's
     deletion of such VSAT. Software license fees are non-refundable.

4.2  Purchase requests (hereinafter "Order(s)") placed by Customer shall be
     issued in writing by an authorized representative of Customer.

4.3  All Orders placed by Customer shall be delivered to the attention of ITCD's
     Vice President of Project Services. In any event, all Orders must include
     the following information:

     (a)  Quantity of Equipment, Software or Services being ordered;

     (b)  Description of Equipment, Software or Services being ordered;

     (c)  Requested delivery date;

     (d)  Prices applicable to such Equipment, Software or Services;

     (e)  Customer's purchase order number;

     (f)  Shipping destination/location (including address) of sites for which
          Services or Equipment will be provided;

     (g)  Invoice address.

     (h)  Shall include payment of fifty percent (50%) of total price for all
          Equipment and Software ordered.

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4.4  ITCD will review and acknowledge in writing Customer's Order and requested
     delivery schedule within ten (10) days from date of receipt thereof. The
     actual delivery schedule shall be in accordance with ITCD's acknowledgment
     letter. ITCD will use its reasonable best efforts to meet Customer's
     delivery schedule, but ITCD cannot warrant or guarantee that any item will
     be delivered prior to the Delivery ARO date for such item, unless, as to
     Equipment, such date is otherwise agreed to in writing between the parties.
     However, without Customer's consent, ITCD will not deliver prior to
     Customer's requested delivery schedule nor extend the delivery schedule
     beyond the Delivery ARO date set forth in Appendix B. As and when ITCD
     receives notice from its vendors that they cannot achieve the ARO date and
     offering a new ARO date, ITCD shall promptly notify Customer of the same.
     Within three (3) business days after Customer's receipt of such notice,
     Customer shall notify ITCD in writing whether Customer accepts or rejects
     the new ARO date. In the event that Customer does not receive notice from
     ITCD stating that a delivery will be delayed, but a shipment does not
     arrive on the ARO date, Customer will be deemed to have rejected a new ARO
     date, unless that parties agree otherwise in writing. In the event Customer
     rejects the new ARO date, then the Order shall be deemed cancelled and
     Customer shall have no further obligation therefor and ITCD shall refund
     the deposit paid by Customer. In the event that Customer accepts the new
     ARO date or if Customer fails to notify ITCD of its rejection within the
     time required, the Order shall deemed revised with such new ARO date and
     Customer shall remain liable for payment for the Ordered Equipment and
     Software.

4.5  The terms and conditions of this Agreement are hereby deemed incorporated
     into and made a part of each Order. Any terms and conditions added to an
     Order for Equipment, Software or Services that are in addition to,
     inconsistent with or different from the terms and conditions of this
     Agreement, shall be void and of no effect unless expressly agreed to by in
     writing by both parties.

ARTICLE 5. TERM

The term of this Agreement shall continue in effect until July 31, 2002.
Thereafter, all Services shall cease unless prior to the last day of the Term,
the Parties have executed a new agreement or have executed a written agreement
to extend the terms of this Agreement.

ARTICLE 6. PAYMENT TERMS AND PENALTIES

6.1  During the term of the Agreement, the parties agree that Customer will pay
     ITCD for all Network Management Fees, Software Maintenance Fees, Equipment
     Maintenance Fees and Software License Fees and all other fees set forth on
     Appendix B related to Services and Equipment ordered hereunder as set forth
     below:

     A)   Baseline Charges. Customer agrees to pay ITCD $161,600.00 (the
          "Baseline Amount"), for Network Management, Software Maintenance,
          Uplinking Fees, Equipment Cabinet Space Fees, and Equipment
          Maintenance Fees ("Monthly Recurring Charges"), via electronic wire
          transfer on the seventh (7th) business day of each month (the
          "Baseline Due Date"). This Baseline Amount represents the estimated
          recurring monthly amount due to ITCD for Services to be rendered by
          ITCD during the month in which the payment is made. Customer agrees to
          pay interest charges of one and one half percent (1.5%) per month on
          any Baseline Amount not received by the appropriate Baseline Due Date.
          ITCD shall invoice Customer for actual monthly recurring charges. In
          the event that in a given month Customer's actual Monthly Recurring
          Charges are less than the Baseline Amount, Customer shall have the
          right to deduct the overpaid amount from the next Baseline Amount
          payment due.

     B)   Additional Charges. In the event that Customer's actual Monthly
          Recurring Charges (or other nonrecurring charges invoiced) exceed the
          Baseline Amount (the "Additional Amounts"), then Customer agrees to
          pay all undisputed Additional Amounts within thirty (30) days after
          receipt of the invoice for the same ("Additional Due Date"). Customer
          agrees to pay interest charges of one and one half percent (1.5%) per
          month on any Additional Amounts not received by appropriate Additional
          Due Date. In the event Customer disputes any Additional Charges,
          Customer shall notify ITCD in writing prior to the Additional Due Date
          for such amount.

     C)   Software License Fees. ITCD shall invoice Customer in advance for all
          annual software license fees described in Appendix C (the "License
          Fees"). Customer agrees to pay all such annual License Fees in

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          conjunction with its next regularly scheduled Baseline Due Date
          occurring after its receipt of the invoice. Customer agrees to pay
          interest charges of one and one half percent (1.5%) per month on any
          License Fee not received by appropriate Baseline Due Date.

     D)   Equipment Purchases. For each Order of Equipment and Software,
          Customer shall submit with such Order payment of fifty percent (50%)
          of the purchase price for the Equipment and Software. Upon shipment of
          the Order, ITCD shall invoice Customer for the remaining fifty percent
          (50%) of the purchase price, together with all freight, taxes and
          other applicable charges. Customer agrees to pay all such charges
          within thirty (30) days after Customer's receipt of the invoice
          ("Purchase Due Date"). Customer agrees to pay interest charges of one
          and one half percent (1.5%) per month on any Equipment or Software
          Fee not received by the Purchase Due Date.

     E)   Payment of Pre-petition Amounts. Pursuant to an Order entered by the
          Bankruptcy Court on July 20, 2001, Customer agrees that it will cure
          the $232,296.32 ($224,423.19 for NMS and $7,883.13 for Internet)
          pre-petition debt it owes to ITCD by paying ITCD such pre-petition
          arrearage in six equal payments over a six month period beginning on
          the first Baseline Due Date occurring after the Order affirming such
          payment is entered by the Court. Each of the six monthly payments will
          be made via wire transfer on the same day that Customer remits the
          Baseline Amount each month until the pre-petition arrearage is cured.
          Customer agrees to pay interest charges of one and one half percent
          (1.5%) per month on any such payment not received by the appropriate
          Baseline Due Date.

ARTICLE 7. WARRANTY

7.1  With respect to Equipment purchased after the Effective Date, ITCD warrants
     the materials manufactured by NECAM to be free from defects in material and
     workmanship, and to conform with NECAM's design specifications. ITCD's
     liability under this warranty shall terminate within twelve (12) months
     from date of shipment. ITCD shall repair or replace any equipment
     (hereinafter "Item") which is defective as to workmanship or materials,
     provided that: a) written notice of any defect is given to ITCD promptly
     upon discovery of the claimed defect, and such notice is given within the
     warranty period specified above; b) the defective Item(s) is returned to
     ITCD with freight prepaid to be paid by Customer; and c) an inspection of
     the returned Item(s) by ITCD indicates that the defect was not caused by
     abuse or improper use, maintenance, repair, storage, negligent handling or
     alteration by other than ITCD, NECAM or its authorized service center. Also
     excluded from the terms of the warranty are Items of characteristically
     indeterminate life, such as bulbs, fuses, etc. The decision to repair or
     replace shall be at ITCD's sole option. Any Item(s) repaired or replaced by
     ITCD pursuant to the terms of this warranty, shall continue to be warranted
     for the remainder of the original warranty period or for a period of ninety
     (90) days from the date of shipment or the repair or replacement, whichever
     occurs last. Item(s) which are replaced hereunder shall automatically
     become the property of ITCD and their replacement shall become the property
     of Customer. ITCD warrants Equipment not manufactured by NECAM's design
     only to the extent of the warranty obtained from the supplier thereof. ITCD
     will notify Customer in writing of any Equipment Ordered by Customer which
     is not manufactured by NECAM and will specify the length of the warranty on
     such Equipment, if any, prior to Customer's purchase of the same. In no
     event shall ITCD's aggregate liability under this warranty exceed the cost
     of repair or replacement of such defective Item.

7.2  EXCEPT AS PROVIDED IN SECTION 7.1 OR SECTION 18.4, ITCD MAKES NO
     REPRESENTATION OR WARRANTY REGARDING THE EQUIPMENT, SOFTWARE OR SERVICES,
     EXPRESSED, IMPLIED OR STATUTORY (INCLUDING, WITHOUT LIMITATION, THE
     WARRANTIES OF NON-INFRINGEMENT, MERCHANTABILITY OR FITNESS FOR A PARTICULAR
     PURPOSE) ALL OF WHICH ARE HEREBY DISCLAIMED.

7.3  ITCD's liability for any and all claims of any kind (except intellectual
     property infringement) regarding the Equipment, Software and Services,
     including negligence, breach of warranty, or otherwise, shall, in the
     aggregate, not exceed Customer's purchase price for the particular item of
     Equipment, Software, or Service which is the subject of such claim. ITCD's
     liability for any and claims of any kind regarding intellectual property
     infringement shall be limited to the greater of Customer's purchase price
     for the particular item of Equipment, Software or Service or the maximum
     amount of any indemnity that ITCD is entitled to from the manufacturer or
     third party provider of the Equipment Software or Service; provided,
     however, such indemnity from the manufacturer or third party provider shall
     be prorated among Customer and all ITCD's other customers having similar
     claims relating to the same Alleged Infringing Apparatus (as defined
     herein).

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7.4  In no event shall either party be liable for indirect, special, incidental
     or consequential damages resulting from or arising out of its performance
     or failure to perform any of its obligations under this Agreement, for any
     warranty made hereunder, or for any other claim or loss arising out of,
     based upon or relating in any manner to the Equipment, Software, Services
     or this Agreement, whether or not such party has been advised, or should
     have known of the possibility of such damages, including, but not limited
     to, lost profits, loss of use of equipment, cost of capital, cost of
     substitute facilities, equipment downtime costs or claims of the Customer's
     customers.

7.5  Each party hereby represents and warrants to the other that:

     (a)  It is a corporation duly organized, validly existing and in good
          standing under the laws of the State of Delaware, and has full and
          unrestricted power and authority, corporate or otherwise, to execute
          and deliver this Agreement and to carry out the transactions
          contemplated hereby;

     (b)  The execution, delivery and performance of this Agreement has been
          duly and validly authorized by all necessary corporate actions (none
          of which actions have been modified or rescinded, and all of which
          actions are in full force and effect) and that this Agreement
          constitutes a valid and binding obligation enforceable in accordance
          with its terms; and

     (c)  Neither the execution and delivery of this Agreement or any document,
          agreement or instrument contemplated hereby nor the consummation of
          the transactions contemplated hereby or thereby will constitute a
          violation of, or default under, or conflict with, any term or
          provision of any contract, commitment, indenture, lease or other
          agreement to which such party is a party or by which such party is
          bound.

ARTICLE 8. TITLE AND DELIVERY

Title to each item of Equipment shall pass to Customer upon final payment to
ITCD. Risk of loss shall pass to Customer upon shipment of each item of
Equipment or Software from the manufacturer.

ARTICLE 9. ACCEPTANCE

          The Equipment and Software ordered after the Effective Date shall be
          deemed accepted by Customer twenty (20) days after receipt unless
          Customer gives ITCD written notice of rejection within such time. The
          notice of rejection shall specify the manner in which the Equipment or
          Software fails to conform to the Order and/or the specifications set
          forth on Appendix A. Acceptance of the Equipment and Software shall
          relieve ITCD of all further responsibility relative to the Equipment
          or Software except as expressly provided in Appendix E (Equipment
          Maintenance Service) and Appendix F (Software Maintenance Service) of
          this Agreement, Section 18.4 (Indemnification) and the warranty set
          forth in Section 7.1, which may survive acceptance.

ARTICLE 10. DESIGN CHANGES

          The design of the Equipment or Software may be altered or changed from
          time to time by the Equipment manufacturer or Software developer,
          provided however, that no change or alteration shall be made which
          deviates from the specifications as detailed in Appendix A unless
          consented to in writing by Customer, which consent shall not be
          unreasonably withheld, conditioned or delayed. Notwithstanding the
          foregoing, the Equipment manufacturer and Software owner shall have
          the right to change or alter the design or specifications for the
          Equipment or Software in order to comply with the statutes, laws,
          rules, regulations, orders or decrees of any government or regulatory
          authority, without the consent of Customer. To the extent ITCD
          receives notice of such change from the manufacturer or developer,
          ITCD shall provide Customer with prompt written notice of all such
          changes required in accordance with the preceding sentence.

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ARTICLE 11. SOFTWARE LICENSE AND RIGHTS IN DATA

Customer acknowledges that all Software associated with the operation of each
VSAT or other Equipment is owned by NECAM or other third parties and licensed to
Customer in connection with Customer's purchase of such Equipment or Software.
Nothing in this Agreement is intended to transfer to Customer any rights to
proprietary data including, but not limited to, design, engineering and
technical information, whether or not patentable, and trade secret information
related to either Equipment or Software contained therein. Any and all Software
purchased hereunder or to be serviced by ITCD pursuant to this Agreement,
including Software utilized or embedded in any Equipment, shall be used
exclusively with such Equipment, shall be maintained by ITCD or NECAM according
to Appendix F and shall remain confidential, and, except as provided below in
this Article 11, shall not be copied, disclosed, reverse engineered or
disseminated in any fashion by Customer or to any third party without the
express written consent of ITCD and NECAM. The sole exception to the prohibition
on copying Software shall be with respect to SNMS software, for which the
Customer shall be allowed to retain one (1) back-up copy for use at its
Alternative Hub location, in the event of a catastrophic failure of the primary
SNMS. Additionally, in the event of a catastrophic failure the primary SNMS
system located at the Primary Hub may be used to operate Equipment at the
Alternate Hub, or, if the Alternate Hub is operated under the control of
Customer or its nominee, in the event of a catastrophic failure affecting the
Primary Hub, the primary SNMS system located at the Alternate Hub may be used to
operate Equipment at the Primary Hub. With the exception of maintenance testing
done from time to time, Customer shall not use the primary SNMS at the Alternate
Hub concurrently with use of the primary SNMS at the Primary Hub, whether for
satellite access, load-sharing or any other purpose, without the prior written
consent of ITCD and NECAM, and only upon payment of such additional license fees
as ITCD may require.

ARTICLE 12. FORCE MAJEURE

ITCD shall not be liable for or be in default under this Agreement for any
delays or any failure to perform under this Agreement due to unforeseen
circumstances or causes beyond its reasonable control, including, but not
limited to, acts of God, war, riots, embargoes, acts of any government, fires,
floods, explosions, the elements, epidemics, strikes, lockouts, satellite
failure, or Customer's acts or omissions; provided, however, loss of business,
customers, or adverse market or financial conditions that may adversely affect a
party's performance shall not be deemed events of force majeure.

ARTICLE 13. NOTICES

In addition to such other requirements as may be set forth herein, any notices
hereunder by one party to the other party shall be given in writing by personal
delivery or by recognized overnight delivery service or posted by certified mail
return receipt requested, to the parties at the addresses set forth below each
party's signature. Notices will be deemed to have been given hereunder when
delivered (whether or not accepted by the addressee).

ARTICLE 14. PROPRIETARY INFORMATION

14.1 Should proprietary information of either Customer or ITCD be required by
     the other in the performance of this Agreement, the party receiving such
     proprietary information ("Recipient" hereafter) hereby agrees to receive
     and maintain same in confidence and to take such precautions as may be
     reasonably necessary to protect same from disclosure to others, or use by
     itself or others for any purpose inconsistent with this Agreement without
     prior written consent of the other party. Precautions taken shall be deemed
     reasonable if at least equivalent to Recipient's precautions with respect
     to its own proprietary information. Proprietary information shall mean
     technical or business information or data conveyed in written, graphic, or
     other permanent tangible form identified as being proprietary or, in the
     case of oral conveyances, any such information which a party identifies to
     the other party in writing as confidential within thirty (30) days after
     the oral conveyance. The Recipient shall use the proprietary information of
     the other party solely in connection with the performance of Recipient's
     obligations under this Agreement.

14.2 The foregoing confidentiality restrictions, however, shall not extend to
     any part of the proprietary information which:

     (a)  was already known to Recipient at the time of disclosure under this
          Agreement as can be established by written documentation;

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     (b)  was known or was generally available to the public at the time of
          disclosure hereunder;

     (c)  becomes known or generally available to the public (other than by act
          of Recipient) subsequent to its disclosure hereunder;

     (d)  is disclosed or made available in writing to Recipient by a third
          party having an apparent bona fide right to do so;

     (e)  is independently developed by Recipient without the use of the
          proprietary information as can be established by written
          documentation; or

     (f)  is required by law to be released.

14.3 Technology Rights

     ITCD and Customer acknowledge and agree that (i) Customer is the sole and
     exclusive owner of any and all trade secrets, know-how and proprietary
     technical information, copyrightable material, including drawings,
     documents, reports, schematics, parts lists, and specifications, and
     inventions, whether or not patentable, that are related to the subject
     matter of this Agreement, specifically including, without limitation,
     Appendix A, that are developed solely and exclusively by Customer in
     connection with the negotiation or performance of this Agreement
     (collectively, "Customer Technology"); (ii) ITCD is the sole and exclusive
     owner of any and all trade secrets, know-how and proprietary technical
     information, copyrightable material, including drawings, documents,
     reports, schematics, parts lists, and specifications, and inventions,
     whether or not patentable, that are related to the subject matter of this
     Agreement, specifically including, without limitation, Appendix A, that are
     developed solely and exclusively by ITCD in connection with the negotiation
     or performance of this Agreement (collectively, "ITCD Technology"); and
     (iii) ITCD and Customer shall jointly own any and all trade secrets,
     know-how and proprietary technical information, copyrightable material,
     including drawings, documents, reports, schematics, parts lists, and
     specifications, and inventions, whether or not patentable, that are related
     to the subject matter of this Agreement, specifically including Appendix A,
     that are jointly developed by ITCD and Customer in connection with the
     negotiation or performance of this Agreement (collectively, "Jointly Owned
     Technology"). Notwithstanding anything in this Agreement to the contrary,
     any and all trade secrets, know-how and proprietary technical information,
     copyrightable material, including drawings, documents, reports, schematics,
     parts lists and specifications, and inventions, whether or not patentable,
     that are related to the VNI and the features, functions and performance of
     entities within the VNI and the protocols that interfaces to the VNI, shall
     be included within "ITCD Technology"; and, notwithstanding anything in this
     Agreement to the contrary, any and all trade secret know-how and
     proprietary technical information, copyrightable material, including
     drawings, documents, reports, schematics, parts lists and specifications,
     and inventions, whether or not patentable, that are related to Customer
     provided equipment and components connected to the VNI, as defined in
     Appendix A, ("Connected Components") are included in "Customer Technology".

     Customer and ITCD hereby grant one to the other and ITCD and Customer
     hereby accept from each other the irrevocable, perpetual, worldwide,
     royalty-free, unlimited, non-exclusive right and license to any and all
     Jointly Owned Technology, including the right to use, copy, modify,
     distribute and sublicense any and all copyrightable materials, and the
     right to fully exercise without restriction any and all of the rights
     pertaining to such Jointly Owned technology, whether for Customer's or
     ITCD's own internal use, for the benefit of any of Customer's or ITCD's
     current or future customers, or for any other reason whatsoever.

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ARTICLE 15. SAFETY

Each party will make certain that Worker's Compensation Insurance covering its
employees and installation contractors is in force. Each Party will provide its
services in accordance with applicable safety requirements, including, without
limitation, the requirements of the Occupational Safety and Health Act of 1970,
as amended.

ARTICLE 16. WAIVER

No failure of either party to exercise any power hereunder or to insist upon
strict compliance by the other party with any obligation or provisions
hereunder, and no custom or practice of the parties at variance with the terms
hereunder shall constitute a waiver of the right to demand exact compliance with
the terms hereof.

ARTICLE 17. COMPLIANCE WITH APPLICABLE LAW AND REGULATIONS

17.1 ITCD represents that all items of Equipment sold and Services provided
     under this Agreement comply with applicable laws and regulations of the
     United States, including, but not limited to, The Communications Act of
     1934, as amended, and the Rules and Regulations of the Federal
     Communications Commission ("FCC").

17.2 During the Term, provided that Customer is not in default of this
     Agreement, ITCD shall maintain its authorization to operate the Primary Hub
     (55 Marietta Street, Atlanta, Georgia) and include in such license VSAT
     sites of Customer controlled by ITCD's Primary Hub. ITCD shall have no
     responsibility with respect to licenses and approvals necessary for the
     Alternate Hub.

17.3 Except for the authorization otherwise set forth in Section 17.2, it shall
     be the responsibility of Customer to obtain any licenses, permits, and
     zoning approvals for the installation and operation of the Equipment and
     Software at the site at which the Equipment and Software is to be
     installed. Customer's failure to obtain necessary licenses and/or permits
     shall not relieve Customer of its obligations hereunder.

17.4 ITCD agrees to provide reasonable assistance to Customer in obtaining
     necessary licenses and permits to operate the Equipment or Software. Such
     assistance shall include providing the technical information related to
     the Equipment or Software necessary to file for or pay any costs associated
     with such licenses or permits. Such assistance shall in no way imply an
     obligation on the part of ITCD to file for such licenses or permits on
     behalf of the Customer.

ARTICLE 18. INDEMNIFICATION

18.1 Customer assumes liability for, and hereby agrees to indemnify and save
     harmless ITCD, its subcontractors, employees, officers, directors,
     successors and assigns, from and against any and all liabilities,
     obligations, losses, damages, claims, demands, penalties, actions, costs
     and expenses, including reasonable attorney's fees and expenses, of
     whatever kind and nature arising out of Customer's use, operation,
     ownership (except with regard to ITCD's warranty obligations pursuant to
     Section 7.1 herein), or of any item of Equipment, Software or Services,
     regardless of where, how and by whom operated, or arising out of any
     failure on the part of Customer to perform or comply with any provision of
     this Agreement. The foregoing indemnification obligation of Customer shall
     not affect ITCD's warranty obligations under Section 7.1 Notwithstanding
     the foregoing, Customer's obligation to indemnify ITCD shall not apply to
     any intellectual property claim made by a third party which is based on
     ITCD operation or use of the Equipment, Software or Services in an
     infringing manner.

18.2 Customer shall indemnify ITCD and save it harmless from loss and damage,
     including infringement (including reasonable attorney's fees) and claims
     by any third parties associated with, caused by, or resulting from the
     transmission of the Customer's data.

18.3 The Customer shall indemnify ITCD from any claim made relating to any
     warranty or representation made by Customer to any third party (including,
     without limitation, its customers) relating to the Equipment, Software or
     any Services provided by ITCD hereunder.

                                                                    Page 8 of 12

                                Master Agreement
                        ITC DeltaCom Communications, Inc.

<PAGE>
                                MASTER AGREEMENT

18.4 ITCD agrees that in the event any Equipment or Software is alleged to
     infringe any valid U.S. patent, ("Alleged Infringing Apparatus"), ITCD
     shall indemnify Customer as and to the extent of any and all
     indemnification it receives from the manufacturer or developer/owner of the
     infringing Software or Equipment; provided, however, such manufacturer or
     developer/owner indemnification shall be prorated among Customer and all
     other customers of ITCD having similar claims relating to infringement of
     such software or equipment.

18.5 Customer agrees that the indemnification described in Section 18.4 shall
     not apply, and Customer shall indemnify, defend and hold harmless ITCD with
     respect to any claim of U.S. patent infringement which may be brought
     because of (a) ITCD's or the manufacturer's compliance with Customer's
     particular design requirements, specifications or instructions, or (b)
     Customer's use of the Alleged Infringing Apparatus in combination with
     other apparatus not supplied by ITCD or the manufacturer of the Alleged
     Infringing Apparatus, or (c) for a purpose or application inconsistent with
     that specified in Appendix A hereto, or (d) Customer's modification of
     Alleged Infringing Apparatus, or (e) work that ITCD performs under this
     Agreement with respect to any other third party hardware or software other
     than NEC America Equipment and Software. In no event shall ITCD's total
     liability under Section 18.4 exceed the greater of the purchase price paid
     by Customer for the Alleged Infringing Apparatus or the amount of the
     indemnity ITCD receives from the manufacturer or developer/owner of the
     infringing Equipment, Service or Software; provided, however, such
     manufacturer or developer/owner indemnification shall be prorated among
     Customer and all other customers of ITCD having similar claims relating to
     infringement of such software, service or equipment. In any such suit so
     defended, if the use of the Alleged Infringing Apparatus is held to
     constitute an infringement and is enjoined, or if in light of any claim
     ITCD deems it advisable to do so, ITCD will, at its option, either procure
     the right to continue the use of the same for Customer, replace the same
     with non-infringing apparatus, modify the same so as to be non-infringing,
     or if none of the foregoing are reasonably practicable, take back the
     Alleged Infringing Apparatus, and refund its respective purchase price less
     a reasonable allowance for use, damage or obsolescence.

ARTICLE 19. GOVERNING LAW

THIS AGREEMENT, ITS FORMATION, CONSTRUCTION, AND INTERPRETATION SHALL BE
GOVERNED BY THE LAWS OF THE STATE OF ALABAMA (EXCLUDING CONFLICTS OF LAWS
PRINCIPLES).

ARTICLE 20. ASSIGNMENTS

Neither party may assign this Agreement without the prior written consent of the
other party, which consent shall not be unreasonably withheld. Notwithstanding
the foregoing, either party may assign its rights under this Agreement, without
the written consent of the other party, to any Affiliate, or to any successor by
merger, divestiture, consolidation or reorganization, or to any purchasers of
all or substantially all of the assets of the business of such party, subject to
the assignee's written agreement to be bound by the terms of this Agreement. In
addition, ITCD may assign and pledge its interest under this Agreement as
security for indebtedness without the prior written consent of Customer. ITCD
shall also have the right to subcontract work hereunder in the normal course of
business without obtaining Customer's written consent, but such subcontracting
shall not relieve ITCD of any obligation or responsibilities under this
Agreement.

ARTICLE 21. DEFAULT BY CUSTOMER

21.1 An Event of Default shall occur if:

     (a)  Customer fails to pay any charge or amount on the Baseline Due Date,
          Additional Due Date, or Purchase Due Date, as applicable, and such
          failure continues for a period of five (5) business days after
          Customer's receipt of written notice thereof from ITCD;

     (b)  Customer fails to perform or observe in any material respect any
          covenant or agreement to be performed or observed by it hereunder and
          such failure continues uncured for thirty (30) days after Customer's
          receipt of written notice thereof from ITCD, unless such failure is
          not reasonably correctable within such thirty (30) day period in which
          case an Event of Default by Customer shall not occur if Customer
          commences and diligently pursues corrective action within such thirty
          (30) day period as soon as possible after being so notified.

                                                                    Page 9 of 12

                                Master Agreement
                        ITC DeltaCom Communications, Inc.

<PAGE>

                                MASTER AGREEMENT

     (c)  Customer, ceases doing business as a going concern, makes an
          assignment for the benefit of creditors, admits in writing its
          inability to pay its debts as they become due, files a voluntary
          petition in bankruptcy, is adjudicated as bankrupt or an insolvent,
          files a petition seeking for itself any reorganization, arrangement,
          composition, readjustment, liquidation, dissolution or similar
          arrangement under any present or future statute, law or regulation or
          files an answer admitting the material allegations of a petition filed
          against it in any such proceeding, consents to or acquiesces in the
          appointment of a trustee, receiver or liquidator of it or of all or
          any substantial part of its assets or properties, or if it or its
          shareholders shall take any action looking to its dissolution or
          liquidation; provided, however, Customer shall not be in default by
          virtue of Customer's pending bankruptcy case filed in the U.S.
          Bankruptcy Court, Northern District of Texas, Dallas Division (Case
          No. 01-34275-SAF-11) ("Bankruptcy Case");

     (d)  If within sixty (60) days after the commencement of any proceedings
          against Customer seeking reorganization, arrangement, readjustment,
          liquidation, dissolution or similar relief under any present or future
          statute, law or regulation, such proceedings shall not have been
          dismissed, or if within sixty (60) days after the appointment without
          Customer's consent or acquiescence of any trustee, receiver or
          liquidator of it or of all or any substantial part of its assets and
          properties, such appointment shall not have been vacated; provided,
          however Customer shall not be in default by virtue of the Bankruptcy
          Case.

21.2 Upon the occurrence of an Event of Default, ITCD may, immediately terminate
     this Agreement and terminate ITCD's performance of its duties hereunder.
     Customer hereby acknowledges and agrees that the court in the Bankruptcy
     Case has entered an Order dated July 20, 2001, stating that the automatic
     stay of 11 USC 362 has been modified such that ITCD may immediately proceed
     to enforce any of its rights and remedies with respect to Customer in the
     event of a post-assumption default after five (5) business days written
     notice and opportunity to cure has lapsed. Any termination of the Agreement
     shall not terminate or otherwise affect any parties' obligations under any
     and all other valid Agreements or Contracts, including the Satellite
     Services Supplemental Agreement which shall remain in full force and
     effect.

21.3 Despite termination of this Agreement, Customer shall remain responsible
     for all amounts then due to ITCD and Customer shall pay for all damages
     proven to result from Customer's default under this Agreement.

ARTICLE 22. DEFAULT BY ITCD

22.1 An Event of Default shall occur if:

     (a)  ITCD shall fail to perform or observe in any material respect any
          covenant or agreement to be performed or observed by it hereunder
          (excluding any covenant or agreement the sole remedies for which are
          provided in Appendix G) and such failure continues uncured for thirty
          (30) days after receipt of written notice thereof to ITCD by Customer,
          unless such failure is not reasonably correctable within such thirty
          (30) day period in which case an Event of Default by ITCD shall not
          occur if ITCD commences and diligently pursues corrective action
          within such thirty (30) day period as soon as possible after being so
          notified;

     (b)  ITCD ceases doing business as a going concern, makes an assignment for
          the benefit of creditors, admits in writing its inability to pay its
          debts as they become due, files a voluntary petition in bankruptcy, is
          adjudicated as bankrupt or an insolvent, files a petition seeking for
          itself any reorganization, arrangement, composition, readjustment,
          liquidation, dissolution or similar arrangement under any present or
          future statute, law or regulation or files an answer admitting the
          material allegations of a petition filed against it in any such
          proceeding, consents to or acquiesces in the appointment of a trustee,
          receiver or liquidator of it or of all or any substantial part of its
          assets or properties, or if it or its shareholders shall take any
          action looking to its dissolution or liquidation;

     (c)  If within sixty (60) days after the commencement of any proceedings
          against ITCD seeking reorganization, arrangement, readjustment,
          liquidation, dissolution or similar relief under any present or future
          statute, law or regulation, such proceedings shall not have been
          dismissed, or if within sixty (60) days after the appointment without
          ITCD's consent or acquiescence of any trustee, receiver or liquidator
          of it or of all or any substantial part of its assets and properties,
          such appointment shall not have been vacated.

                                                                   Page 10 of 12

                                Master Agreement
                        ITC DeltaCom Communications, Inc.

<PAGE>

                                MASTER AGREEMENT

22.2 Upon the occurrence of an Event of Default, Customer may, upon written
     notice to ITCD, immediately terminate this Agreement. Any termination of
     the Agreement shall not terminate or otherwise affect any parties'
     obligations under the Satellite Services Supplemental Agreement, which
     shall remain in full force and effect.

22.3 Despite termination of this Agreement, Customer shall remain responsible
     for all amounts then due to ITCD under this Agreement up to the date of
     termination.

22.4 ITCD will in good faith assist Customer in a smooth transition to
     Customer's new service provider.

ARTICLE 23. SEVERABILITY

If any provision of this Agreement is held invalid, the remainder of this
Agreement shall not be affected thereby.

ARTICLE 24. ABILITY TO ENTER AGREEMENT

The parties executing this Agreement hereby covenant and warrant that the
corporation has full right and authority to enter into this Agreement, and that
each of the persons signing on behalf of the corporation are duly authorized to
do so.

ARTICLE 25. RELATIONSHIPS OF PARTIES

This Agreement is not intended to constitute or create a joint venture, pooling
arrangement, partnership, agency or business organization of any kind. ITCD and
Customer shall be independent contractors for all purposes and neither party
shall act as or hold itself out as agent for the other or create or attempt any
obligations or liabilities on behalf of the other party.

ARTICLE 26. ENTIRETY OF AGREEMENT

This Agreement consists only of this document upon which the parties have
affixed their signatures and those documents specifically incorporated herein by
reference. This Agreement as so constituted is the entire Agreement between the
parties with respect to the subject matter hereof and supersedes all other
previous statements and contracts, communications or agreements, whether oral or
written with respect to the subject matter hereof. This Agreement is independent
of the Third Amended and Restated Satellite Services Supplemental Agreement
between ITCD and Customer dated August 1, 2001, and does not amend or modify
such contract, which remains in full force and effect. No modification, of any
provision hereof shall be binding upon the parties unless evidenced in writing
and signed by both parties.

ARTICLE 27. SERVICE LEVEL AGREEMENT

See the attached Appendix G.

                                                                   Page 11 of 12

                                Master Agreement
                        ITC DeltaCom Communications, Inc.

<PAGE>

                                MASTER AGREEMENT

IN WITNESS WHEREOF, the parties hereto, each by a duly authorized officer, have
caused this Agreement to be executed as of the date written above.

WEBLINK WIRELESS, INC.                     ITC DELTACOM COMMUNICATIONS, INC.

By:    Douglas S. Glen                     By:    Harold E. Cowan
       -----------------------------              -----------------------------

Title: Senior Vice President               Title: Vice President
       -----------------------------              -----------------------------

Date:  7-31-01                             Date:  August 1, 2001
       -----------------------------              -----------------------------

By:    /s/ DOUGLAS S. GLEN                 By:    /s/ HAROLD E. COWAN
       -----------------------------              -----------------------------

Address for Notice:                        Address for Notice:

WebLink Wireless, Inc.                     ITC DeltaCom Communications, Inc.

3333 Lee Parkway, Suite 100                55 Marietta Street, 18th Floor

Dallas, Texas 75219                        Atlanta, Georgia 30303

Attention: V.P. Network Operations         Attention:  V.P. of Project Services

With a Copy to (which shall not constitute notice):

WebLink Wireless, Inc.                     ITC DeltaCom Communications, Inc.

3333 Lee Parkway, Suite 100                4092 S. Memorial Parkway

Dallas, TX 75219                           Huntsville, Alabama 35802

Attention: General Counsel                 Attention: Assistant General Counsel

[STAMP]

                                                                   Page 12 of 12

                                Master Agreement
                        ITC DeltaCom Communications, Inc.<PAGE>
                                                                   EXHIBIT 10.16

                         FIFTH AMENDMENT TO OFFICE LEASE

         THIS FIFTH AMENDMENT TO OFFICE LEASE (this "Fifth Amendment") is
entered into as of the 21st day of March, 2002, by and between CRESCENT REAL
ESTATE FUNDING VIII, L.P., a Delaware limited partnership ("Landlord"), and
WEBLINK WIRELESS, INC., a Delaware corporation f/k/a Pagemart Wireless, Inc.
("Tenant").

                                    RECITALS:

         A.       Landlord and Tenant executed that certain Office Lease dated
                  November 26, 1996 (the "Original Lease"), covering certain
                  space containing approximately 120,000 rentable square feet
                  (the "Original Premises"), located on the first, seventh,
                  eighth, ninth, tenth, eleventh and twelfth floors of an office
                  building commonly known as 3333 Lee Parkway, and located at
                  3333 Lee Parkway, Dallas, Dallas County, Texas (the
                  "Building").

         B.       The Original Lease has been amended by (i) that certain First
                  Amendment to Office Lease dated July 8, 1997 (the "First
                  Amendment"), pursuant to which the Original Premises were
                  redefined to consist of approximately 140,774 rentable square
                  feet, located on the first, second, eighth, ninth, tenth,
                  eleventh and twelfth floors of the Building; (ii) that certain
                  Second Amendment to Office Lease dated September 15, 1997 (the
                  "Second Amendment"), pursuant to which the Original Premises
                  were expanded to include the fifth floor of the Building,
                  containing approximately 20,194 rentable square feet (the
                  "Expansion Space"); (iii) that certain Third Amendment to
                  Office Lease dated July 24, 1998 (the "Third Amendment"),
                  pursuant to which the Original Premises were redefined to
                  consist of approximately 162,388 rentable square feet, located
                  on the first, second, fifth, seventh, eighth, ninth, tenth,
                  eleventh and twelfth floors of the Building (the "Redefined
                  Premises"); and (iv) that certain Fourth Amendment to Office
                  Lease dated February 1, 1999 (the "Fourth Amendment"),
                  pursuant to which the Original Premises were redefined to
                  consist of approximately 178,531 rentable square feet, located
                  on the first, second, fourth, fifth, seventh, eighth, ninth,
                  tenth, eleventh and twelfth floors of the Building.

         C.       The Original Lease, as modified by the above-described
                  amendments, is hereinafter referred to as the "Lease". Unless
                  otherwise expressly provided herein, capitalized terms used
                  herein shall have the same meanings as designated in the
                  Lease.

         D.       Tenant has filed a petition for reorganization under Chapter
                  11 of the Bankruptcy Code in the Northern District of Texas,
                  Case No. 301-34275SAF-11 (the "Bankruptcy Court").

         E.       Subject to Bankruptcy Court approval of this Fifth Amendment,
                  Tenant desires to further amend, modify, and assume the Lease
                  as amended herein.

<PAGE>

                                   AGREEMENT:

         In consideration of the sum of Ten Dollars ($10.00), the mutual
covenants and agreements contained herein and in the Lease, and for other good
and valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, Landlord and Tenant hereby further amend and modify the Lease as
follows:

         1. CONDITION PRECEDENT. The post-petition effectiveness of the Lease as
amended by this Fifth Amendment is subject to the following conditions
precedent: (i) Tenant shall have filed with the Bankruptcy Court a motion, in
form acceptable to Landlord, to approve Tenant's assumption of the Lease as
amended hereby (including the License Agreement attached as Exhibit A to the
original Lease), authorize Tenant's payment to Landlord of $55,896.00 in
pre-petition debt, authorize Landlord to retain the $190,000 security deposit in
connection with Landlord's execution of this Fifth Amendment; (ii) an Order
shall have been entered by the Bankruptcy Court authorizing Tenant to assume
this Lease as amended by this Fifth Amendment (including the License Agreement
attached as Exhibit A to the original Lease) and approving Tenant's assumption
motion (the "Lease Approval Order"); (iii) Tenant agrees not to challenge
Landlord's unsecured claim of $1,990,322.69 (calculated in accordance with
Section 502(b)(6)(A) of the U.S. Bankruptcy Code), which represents the damages
Landlord has asserted based on Tenant partial termination of the Lease; (iv)
Tenant shall have filed a motion requesting authorization from the Bankruptcy
Court to resolve the dispute between Tenant and T.D. Industries, Inc. and
discharge the mechanics lien filed by T.D. Industries, Inc. in the amount of
$6470.15 (the "Lien Amounts") for work performed on the Premises; and (v) an
order shall have been entered by the Bankruptcy Court authorizing Tenant's
payment of the Lien Amounts.

         2. PREMISES. The Premises is hereby modified and amended to reduce the
current Rentable Area of the Premises from 178,531 rentable square feet (the
"Original Premises") to 89,457 rentable square feet located on the first,
second, tenth, eleventh and twelfth floors as reflected in the attached Exhibit
"A" (the redefined "Premises"). This reduction in the Premises represents a
reduction in 89,074 rentable square feet on the 1st, 4th, 5th, 7th, 8th and 9th
floors (the "Returned Space") as reflected in the attached Exhibit "B".

         3. COMMENCEMENT DATE. The Commencement Date shall be the date the Lease
Approval Order is entered by the Bankruptcy Court.

         4. LEASE TERM. The term of the Lease shall be the Commencement Date
through January 31, 2010.

         5. BASIC RENTAL.

                  (a) Tenant agrees that it will cure the $55,896 pre-petition
debt (the "PrePetition Amount") it owes to Landlord by paying such Pre-Petition
Amount, in lump sum, within five (5) business days after the entry of the Lease
Approval Order approving such payment. Tenant and Landlord acknowledge that
payment of the Pre-Petition Amount does not diminish Landlord's unsecured claim
of $1,990,322.69 in Tenant's Bankruptcy Case relating to the Returned Space.

                                       2

<PAGE>

                  (b) Effective as of the Lease Approval Order, the Lease is
hereby modified and amended to provide that Basic Rental due and payable for the
Premises during the Lease Term shall be:

<Table>
<Caption>
                                                    Basic Rental
                                                    per Rentable               Monthly
Lease Months                                         Square Foot             Basic Rental
-----------------------------------------          ---------------          ---------------
<S>                                                <C>                      <C>
Commencement Date to May 31, 2003                  $         18.95          $    141,267.51
-----------------------------------------          ---------------          ---------------
June 1, 2003 to May 31, 2004                       $         19.20          $    143,131.20
-----------------------------------------          ---------------          ---------------
June 1, 2004 to May 31, 2005                       $         19.70          $    146,858.58
-----------------------------------------          ---------------          ---------------
June 1, 2005 to May 31, 2006                       $         19.95          $    148,722.26
-----------------------------------------          ---------------          ---------------
June 1, 2006 to May 31, 2010                       $         20.20          $    150,585.95
-----------------------------------------          ---------------          ---------------
</Table>

                  (c) The Basic Rental set forth above does not include the
rental and charges set forth in the Rooftop License Agreement.

                  (d) Basic Rental for any partial month shall be pro-rated on a
daily basis. All rental shall be payable in accordance with the terms and
provisions of the Lease, as modified by this Fifth Amendment. Basic Rental for
any partial month shall be pro-rated on a daily basis.

         6. SIGNAGE AND NAMING RIGHTS. Tenant hereby relinquishes all of its
rights to designate the name of the Building. Footnotes 113 and 129 are hereby
deleted from the Lease. Footnote 131(bb) is hereby amended to require Tenant
to permanently remove its exterior signs currently located on the upper portion
of the Building and to restore the areas of the Building to which the signage
was affixed to their condition prior to the installation of the signage within
sixty (60) days from Tenant's receipt of written notice from Landlord, but in no
event sooner than sixty (60) days after the entry of the Lease Approval Order.

         7. SURRENDER OF RETURNED SPACE. On or before 11:59 p.m. of the
thirtieth business day following the Commencement Date, Tenant shall peaceably
surrender to Landlord the Returned Space, including the alterations,
improvements and changes thereto other than Tenant's fixtures. Tenant shall
surrender the Returned Space in the same condition as it was in on the Lease
Commencement Date, subject only to ordinary and customary wear and tear. If any
furnishings, equipment, furniture, trade fixtures or other removable equipment
of Tenant are not removed from the Returned Space on or before 11:59 p.m. on the
date which is the thirtieth day following the Commencement Date, then Tenant
hereby grants to Landlord the option, exercisable at any time thereafter without
the requirement of any notice to Tenant, (a) to treat such property, or any
portion thereof, as being abandoned by Tenant to Landlord, whereupon Landlord
shall be deemed to have full rights of ownership thereof; (b) to sell, give
away, donate

                                       3

<PAGE>

or dispose of as trash or refuse any or all of such property without any
responsibility to deliver to Tenant any proceeds therefrom.

         8. FIRST RIGHT OF REFUSAL DELETED. Rider 301 to the Lease is hereby
deleted.

         9. TERMINATION OPTION. Rider No. 501 of the Lease is hereby deleted in
its entirety and replaced with the following:

         "Notwithstanding anything to the contrary set forth in the Lease,
         Tenant may terminate the Lease as part of a confirmed liquidation plan
         under Chapter 11 or a liquidation under Chapter 7, in which event,
         Landlord shall be entitled to a claim for lost rent which shall be
         limited to the greater of (i) twelve (12) months of Basic Rental and
         Additional Rental payments or (ii) fifteen percent (15%) of the
         remaining Lease obligation if the Lease had not been terminated prior
         to the expiration of the stated term to be computed from the date
         Tenant surrenders the Premises."

         10. BROKER: Tenant represents and warrants that in connection with the
execution of this Fifth Amendment it has dealt directly with and only with the
Staubach Company whose commission, if any, shall be paid by Tenant pursuant to a
separate written agreement. Tenant shall indemnify and hold harmless Landlord
and its designated property management firm, and their respective partners,
members, affiliates, and subsidiaries, and all of their respective officers,
directors, shareholders, employees, partners, members, representatives, and
agents from and against all claims (including costs of defense and
investigation) of any party including the Staubach Company claiming by, through
or under Tenant in connection with this Fifth Amendment.

         11. TIME OF THE ESSENCE. Time is of the essence with respect to
Tenant's execution and the Bankruptcy Court approval of the Lease as amended by
this Fifth Amendment. If Tenant fails to obtain Bankruptcy Court approval to
enter into this Fifth Amendment, and to thereafter execute and deliver a signed
copy of this Lease as amended by this Fifth Amendment to Landlord by 5:00 p.m.
(Dallas, Texas time), on February 15, 2001, it shall be deemed null and void and
shall have no force or effect, unless otherwise agreed in writing by Landlord.
Landlord's acceptance, execution and return of this document shall constitute
Landlord's agreement to waive Tenant's failure to meet the foregoing deadline.

         12. BINDING EFFECT. Except as modified by this Fifth Amendment, the
terms and provisions of the Lease (as previously amended) shall remain in full
force and effect, and the Lease, as modified by this Fifth Amendment, shall be
binding upon the parties hereto, their successors and permitted assigns. This
Fifth Amendment shall become effective only after the full execution and
delivery hereof by Landlord and Tenant.

                  (Remainder of Page Intentionally Left Blank)

                                       4

<PAGE>

         EXECUTED as of the day and year first above written.

<Table>
<S>                                                           <C>
LANDLORD:                                                     TENANT:
CRESCENT REAL ESTATE FUNDING                                  WEBLINK WIRELESS, INC.,
VIII, L.P., a Delaware limited partnership                    a Delaware corporation

By:      CRE Management VIII, LLC
         a Delaware limited liability company
         its general partner                                  By: /s/ SANDRA D. NEAL
                                                                  -----------------------------
                                                              Name: Sandra D. Neal
                                                                    ---------------------------
         By: Crescent Real Estate                             Title: Senior Vice President
         Equities, Ltd., a Delaware                                  --------------------------
         corporation, its Manager

         By: /s/ [ILLEGIBLE]
            ----------------------------
</Table>

                                       5

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