<PAGE>














                             SECOND AMENDED AND RESTATED
                           AGREEMENT OF LIMITED PARTNERSHIP
                                          OF
                             CAPROCK FIBER NETWORK, LTD.









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                                  TABLE OF CONTENTS
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ARTICLE I

DEFINITIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2
       1.01    Terms Defined . . . . . . . . . . . . . . . . . . . . . . . .2
       1.02    Number and Gender . . . . . . . . . . . . . . . . . . . . . .5

ARTICLE II

GENERAL. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
       2.01    Continuation; Admission . . . . . . . . . . . . . . . . . . .5
       2.02    Name. . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
       2.03    Principal Place of Business; Registered Office; Registered 
               Agent . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
       2.04    Purposes. . . . . . . . . . . . . . . . . . . . . . . . . . .5
       2.05    Term. . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

ARTICLE III

CAPITAL CONTRIBUTIONS - PARTNERSHIP INTERESTS. . . . . . . . . . . . . . . .6
       3.01    Initial Capital Contributions . . . . . . . . . . . . . . . .6
       3.02    Additional Capital Contributions. . . . . . . . . . . . . . .6
       3.03    Failure to Make Required Contributions. . . . . . . . . . . .6
       3.04    Capital Accounts. . . . . . . . . . . . . . . . . . . . . . .6
       3.05    Partner Loans . . . . . . . . . . . . . . . . . . . . . . . .7
       3.06    Other Matters Relating to Capital Contributions . . . . . . .7
       3.07    Deficit Capital Account Balances. . . . . . . . . . . . . . .7
       
ARTICLE IV

RIGHTS AND POWERS OF THE GENERAL PARTNER . . . . . . . . . . . . . . . . . .8
       4.01    Duties of General Partner . . . . . . . . . . . . . . . . . .8
       4.02    Reliance by Third Parties . . . . . . . . . . . . . . . . . .8
       4.03    Management of Business. . . . . . . . . . . . . . . . . . . .8
       4.04    Operating Reserve Account . . . . . . . . . . . . . . . . . .9
       4.05    Payment of Costs and Expenses . . . . . . . . . . . . . . . .9
       4.06    Exercise of Rights and Powers . . . . . . . . . . . . . . . .9
       4.07    Compensation. . . . . . . . . . . . . . . . . . . . . . . . .9
       4.08    Liability . . . . . . . . . . . . . . . . . . . . . . . . . .9
       4.09    Indemnification . . . . . . . . . . . . . . . . . . . . . . .9
       4.10    Tax Matters Partner . . . . . . . . . . . . . . . . . . . . 10
       4.11    Guaranty of Debt; Guaranty and Commitment Fees. . . . . . . 11
       4.12    Construction Management . . . . . . . . . . . . . . . . . . 11


                                      -i-
<PAGE>

       4.13    Network Administration. . . . . . . . . . . . . . . . . . . 12
       
ARTICLE V

LIMITED PARTNER MATTERS. . . . . . . . . . . . . . . . . . . . . . . . . . 12
       5.01    Limitation of Liability . . . . . . . . . . . . . . . . . . 12
       5.02    Management. . . . . . . . . . . . . . . . . . . . . . . . . 12
       5.03    Consents. . . . . . . . . . . . . . . . . . . . . . . . . . 12
       5.04    Power of Attorney . . . . . . . . . . . . . . . . . . . . . 12
       5.05    Death, Bankruptcy, Etc. . . . . . . . . . . . . . . . . . . 13
       
ARTICLE VI

ALLOCATIONS AND DISTRIBUTIONS. . . . . . . . . . . . . . . . . . . . . . . 13
       6.01    Allocation of Net Income and Loss from Operations . . . . . 13
       6.02    Distributions of Cash Flow from Operations
               and Major Capital Events. . . . . . . . . . . . . . . . . . 14
       6.03    Limitations on Allocations. . . . . . . . . . . . . . . . . 14
       6.04    Distributions Upon Liquidation of Partnership . . . . . . . 16
       6.05    Liquidation of Partners Interest. . . . . . . . . . . . . . 16
       6.06    In-Kind Distributions . . . . . . . . . . . . . . . . . . . 17
       6.07    Additional Tax Allocation Provisions. . . . . . . . . . . . 17
       
ARTICLE VII

FISCAL MATTERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
       7.01    Fiscal Year . . . . . . . . . . . . . . . . . . . . . . . . 18
       7.02    Books and Records . . . . . . . . . . . . . . . . . . . . . 18
       7.03    Reports and Statements. . . . . . . . . . . . . . . . . . . 18
       7.04    Audit . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
       7.05    Tax Returns . . . . . . . . . . . . . . . . . . . . . . . . 19
       7.06    Bank Accounts . . . . . . . . . . . . . . . . . . . . . . . 19
       7.07    Tax Elections . . . . . . . . . . . . . . . . . . . . . . . 19

ARTICLE VIII

TRANSFERS  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
       8.01    Restriction on Transfers. . . . . . . . . . . . . . . . . . 19
       8.02    Permitted Sales after Right of First Refusal Is Given . . . 19
       8.03    Permitted Transfers . . . . . . . . . . . . . . . . . . . . 20
       8.04    Assumption by Transferee. . . . . . . . . . . . . . . . . . 21
       8.05    Cost of Transfers . . . . . . . . . . . . . . . . . . . . . 21
       8.06    Effect of Attempted Disposition in Violation of this 
               Agreement . . . . . . . . . . . . . . . . . . . . . . . . . 21


                                      -ii-
<PAGE>

ARTICLE IX

RESIGNATION, WITHDRAWAL AND REMOVAL OF GENERAL PARTNER:
ADMISSION OF NEW GENERAL PARTNER . . . . . . . . . . . . . . . . . . . . . 21
       9.01    Voluntary Resignation or Withdrawal of the General Partner. 21
       9.02    Substitute and Additional General Partners. . . . . . . . . 21
       9.03    Admission of a Successor General Partner. . . . . . . . . . 21

ARTICLE X

DISSOLUTION  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
       10.01   Dissolution . . . . . . . . . . . . . . . . . . . . . . . . 22
       10.02   Wind-Up of Affairs. . . . . . . . . . . . . . . . . . . . . 23
       
ARTICLE XI
       
MISCELLANEOUS  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
       11.01   Amendments. . . . . . . . . . . . . . . . . . . . . . . . . 23
       11.02   Other Activities. . . . . . . . . . . . . . . . . . . . . . 23
       11.03   Partition . . . . . . . . . . . . . . . . . . . . . . . . . 23
       11.04   Notices . . . . . . . . . . . . . . . . . . . . . . . . . . 23
       11.05   Provisions Severable. . . . . . . . . . . . . . . . . . . . 23
       11.06   Counterparts. . . . . . . . . . . . . . . . . . . . . . . . 23
       11.07   Headings. . . . . . . . . . . . . . . . . . . . . . . . . . 24
       11.08   Successors and Assigns. . . . . . . . . . . . . . . . . . . 24
       11.09   APPLICABLE LAW. . . . . . . . . . . . . . . . . . . . . . . 24
</TABLE>

                                    -iii-
<PAGE>

                             SECOND AMENDED AND RESTATED
                           AGREEMENT OF LIMITED PARTNERSHIP
                                          OF
                             CAPROCK FIBER NETWORK, LTD.


     This Second Amended and Restated Agreement of Limited Partnership of 
CapRock Fiber Network, Ltd. (the "Agreement") is entered into by and among 
CapRock Systems, Inc., a Texas corporation ("CapRock") as the general partner 
(the "General Partner"), and Jere W. Thompson, Sr. ("Jere Thompson"), 
Margaret Dunlap Thompson ("Peggy Thompson"), Michael D. Thompson ("Michael 
Thompson"), Patrick J. Thompson ("Pat Thompson"), Kimberly A. Thornton ("Kim 
Thornton"), Margaret D. Nelson ("Debbie Nelson"), Christopher D. Thompson 
("Chris Thompson"), David E. Thompson ("David Thompson") (collectively, the 
"Thompson Family"), Mark Langdale ("Langdale"), Jere W. Thompson, Jr. 
("Thompson"), The Hayden Company, a Texas corporation ("Hayden"), Joe C. 
Thompson, Jr. ("Jodie Thompson"), and The Florida Company, a Texas 
corporation ("Florida") as the limited partners (the "Limited Partners").

                                R E C I T A L S:


     A.   CapRock Fiber Network, Ltd., a Texas limited partnership (the 
"Partnership") was formed by that certain Agreement of Limited Partnership of 
CapRock Fiber Network, Ltd. (the "Original Agreement).

     B.   The Original Agreement was amended and restated by that certain 
Amended and Restated Agreement of Limited Partnership of CapRock Fiber 
Network, Ltd. dated May 31, 1993 (the "Amended Agreement").

     C.   The General Partner and the Limited Partners desire to amend the 
Amended Agreement to (i) admit Hayden, Florida and Jodie Thompson as Limited 
Partners, (ii) increase the interests in the Partnership of Thompson and 
Langdale, (iii) amend the allocation and distribution provisions to account 
for a construction loan which has been guaranteed by certain of the Partners, 
(iv) modify the purposes of the Partnership, and (v) otherwise amend the 
Amended Agreement as set forth herein.

                                   AGREEMENT:

     NOW THEREFORE, in consideration of the mutual covenants set forth in 
this Agreement, and for other good and valuable consideration, the receipt 
and sufficiency of which are hereby acknowledged, the General Partner and the 
Limited Partners agree as follows:

<PAGE>

                                      ARTICLE I

                                     DEFINITIONS

     1.01 TERMS DEFINED. When used in this Agreement, the following terms 
shall have the meanings set forth below:

          "Act" shall mean the Texas Revised Limited Partnership Act as set
     forth in Vernon's Revised Civil Statutes Annotated Article 6132a-1, as
     subsequently amended.

          "Affiliate" shall mean a Person who is (i) directly or indirectly,
     through one or more intermediaries, controlling, controlled by, or under
     common control with the Person in question, or (ii) a spouse, child,
     grandchild, parent, sibling or any Person controlled by any of the
     foregoing, of the Person in question, or in case of a Person other than an
     individual, the individual who controls the Person in question. For
     example, a trust for the benefit of the grandchild of the controlling
     shareholder of a Partner that is a corporation, would be treated as an
     Affiliate. The term "control," as used in the immediately preceding
     sentence, means, with respect to an entity that is a corporation, the right
     to exercise, directly or indirectly, more than 50% of the voting rights
     attributable to the shares of such corporation and, with respect to a
     Person that is not a corporation, the possession, directly or indirectly,
     of the power to direct or cause the direction of the management or policies
     of such Person.

          "Capital Contribution" shall mean the cash and the fair market value
     of property other than cash (net of liabilities which the Partnership
     assumes or takes the property subject to) contributed to the capital of the
     Partnership by a Partner.

          "Cash Flow" shall mean, for the period in question, or in the case of
     a Major Capital Event, the event in question, the amount by which the
     aggregate cash receipts of the Partnership from any source (including loans
     and Capital Contributions) exceed the sum of the cash expenditures of the
     Partnership plus a cash reserve in the amount determined by the General
     Partner to be sufficient to meet the working capital requirements of the
     Partnership.

          "Certificate" shall mean the Amended and Restated Certificate of
     Limited Partnership to be filed upon behalf of the Partnership with the
     Secretary of State of Texas in accordance with all applicable statutes.

          "Code" shall mean the Internal Revenue Code of 1986, as amended from
     time to time, and the rules and regulations thereunder.

          "Commitment Fee" shall mean a fee payable to each Guarantor in an
     amount equal to 1% of such Guarantor's Guaranty.

          "Construction Lender" shall mean Bank One, Texas, National
     Association, or such other Person who refinances the Construction Loan or
     becomes a successor in interest to Bank One, Texas, National Association
     with respect to the Construction Loan.


                                       2
<PAGE>

          "Construction Loan" shall mean the loan made by the Construction
     Lender to the Partnership in an amount sufficient to construct, and
     initiate operations of, the Network.

          "General Partner" shall mean CapRock, so long as such Person shall
     continue as a general partner hereunder, and any other Person who has been
     admitted as and continues to be, a general partner of the Partnership.

          "Guarantors" shall mean Jere Thompson, Hayden, Florida, Jodie Thompson
     and Mark Langdale.

          "Guaranty" shall mean with respect to each Guarantor, the limited and
     several amount of the Construction Loan which has been personally
     guaranteed by such Guarantor in accordance with Section 4.11.

          "Guaranty Fee" shall mean an annual amount payable to each Guarantor
     equal to 7% (pro-rated for partial years) of the product of (i) the amount
     of such Guarantor's Guaranty multiplied by (ii) a fraction, the numerator
     of which is the lesser of (A) $8,000,000, or (B) the average outstanding
     daily principal under the Construction Loan during the applicable period
     and the denominator of which is $8,000,000.

          "Limited Partners" shall mean Jere Thompson, Peggy Thompson, Michael
     Thompson, Pat Thompson, Debbie Nelson, Kim Thornton, Chris Thompson, David
     Thompson, Langdale, Thompson, Hayden, Florida and Jodie Thompson so long as
     each such Person shall continue as a limited partner hereunder, and any
     other Person who has been admitted as, and who continues to be, a limited
     partner of the Partnership.

          "Liquidating Event" shall mean the sale, condemnation or exchange of
     all or substantially all of the Network or other transaction which,
     individually or together with any similar transaction or transactions,
     results in the disposition of all or substantially all of the Network and
     occurs in the course of liquidation of the Partnership, or upon and with
     respect to which event the Partnership is wound up and all payments,
     including payments on any promissory notes, have been received.

          "Major Capital Event" shall mean any event (excluding a Liquidating
     Event) arising other than in the ordinary course of the Partnership's
     business, including, without limitation, (i) the sale, exchange or
     disposition of less than substantially all of the Network; (ii) a
     condemnation or disposition of less than substantially all of the Network;
     (iii) the recovery of damage awards or settlements or insurance proceeds
     from the loss of or damage to the Network, and (iv) a borrowing or
     refinancing by the Partnership. The General Partner's designation of an
     event as a Major Capital Event shall be binding upon the Partners and the
     Partnership absent manifest error.

          "Majority in Interest" shall mean Partners (or Partners of a
     designated class) owning more than 50% of the Partnership Interests (or
     Partnership Interests of the designated class).


                                       3
<PAGE>

          "Network" shall mean the fiber optic telecommunications network to be
     constructed, maintained and operated by the Partnership and initially 
     located between Corpus Christi and Houston, Texas, as may be expanded or 
     modified by agreement among the General Partner and a Majority in 
     Interest of the Limited Partners.

          "Operations" shall mean all activities arising in the ordinary course
     of the Partnership's business not constituting a Major Capital Event or a
     Liquidating Event.

          "Partners" shall mean the General Partner and the Limited Partners.
     "Partner" shall mean any one of the Partners.

          "Partnership" shall mean the limited partnership created and existing
     pursuant hereto.

          "Partnership Interest" shall mean a Partner's interest, expressed as a
     percentage in Exhibit "A" in the income, gains, losses, deductions, tax
     credits, voting rights and distributions of the Partnership as may be
     affected by the provisions of this Agreement and as may thereafter be
     adjusted.

          "Person" shall mean an individual, partnership, joint venture,
     corporation, limited liability company, trust, estate or other entity or
     organization.

          "Preferred Return" shall mean, with respect to each Guarantor, a
     cumulative rate of return equal to twelve percent (12%) per annum,
     compounded annually, on such Guarantor's Unreturned Capital Contributions.

          "Proceeding" means any threatened, pending or completed action, suit
     or proceeding, whether civil, criminal, administrative, arbitrative or
     investigative, any appeal in such an action, suit or proceeding, and any
     inquiry or investigation that could lead to such an action, suit or
     proceeding.

          "Section" shall mean any section or subsection in this Agreement.

          "Service" shall mean the Internal Revenue Service.

          "The Thompson Family" shall mean Jere Thompson, Peggy Thompson,
     Michael Thompson, Pat Thompson, Debbie Nelson, Kim Thornton, Chris Thompson
     and David Thompson.

          "Transfers" shall mean the sale, transfer, conveyance, assignment,
     pledge, hypothecation, mortgage or other encumbrance or disposition of all
     or any part of a Partnership Interest.

          "Unpaid Preferred Return" shall mean, as to each Guarantor, an amount
     equal to such Guarantor's Preferred Return less distributions previously
     made to such Guarantor pursuant to Section 6.02 (a)from and after the date
     of this Agreement.


                                       4

<PAGE>

          "Unreturned Capital Contributions" shall mean, as to each 
     Guarantor, the aggregate Capital Contributions made to the Partnership 
     by such Guarantor from and after the date of this Agreement pursuant to 
     Section 3.02(b), reduced by the aggregate distributions to such 
     Guarantor from and after the date of this Agreement from the Partnership 
     pursuant to Section 6.02(b).

     1.02  NUMBER AND GENDER. Whenever the context requires, references in 
this Agreement to the singular number shall include the plural, and the 
plural number shall include the singular, and words denoting gender shall 
include the masculine, feminine and neuter.

                                      ARTICLE II

                                       GENERAL

     2.01 CONTINUATION; ADMISSION.

          (a)  The Partners hereby continue the Partnership as a limited 
     partnership pursuant to the Act for the purposes described in Section 
     2.04. The General Partner shall execute and file on behalf of the 
     Partners and the Partnership a Certificate in accordance with applicable 
     statutory requirements in such offices and places as may be required by 
     the laws of the State of Texas.

          (b)  As of the effective date of this Agreement, Hayden, Florida 
     and Jodie Thompson are admitted to the Partnership as Limited Partners, 
     and the Partnership Interests of the Partners shall be as set forth in 
     Exhibit "A".

     2.02 NAME. The business of the Partnership shall be conducted under the
name "CapRock Fiber Network, Ltd."

     2.03 PRINCIPAL PLACE OF BUSINESS; REGISTERED OFFICE; REGISTERED AGENT.  The
principal place of business, the principal office and the registered office of
the Partnership shall be at 13455 Noel Road, Suite 1925, Lockbox 46, Dallas,
Texas 75240. The General Partner may change the principal place of business of
the Partnership to any other place upon ten (10) days written notice to the
Limited Partners. The registered agent shall be Jere W. Thompson, Jr.

     2.04 PURPOSES. The purposes of the Partnership shall be:

               (a)  to finance, construct, own and operate the Network;

               (b)  to perform all acts which are appropriate or necessary in 
          conjunction with the Partnership financing, constructing, owning 
          and operating the Network; and

               (c)  to do any and all other acts and things necessary, 
          incidental or convenient to carry on the Partnership business as 
          contemplated under this Agreement.


                                      5

<PAGE>

     2.05 TERM. The Partnership shall continue until terminated pursuant to
Section 10.01.

                                     ARTICLE III

                    CAPITAL CONTRIBUTIONS - PARTNERSHIP INTERESTS

     3.01 INITIAL CAPITAL CONTRIBUTIONS. As of the effective date of this 
Agreement, the Partnership has issued Partnership Interests to each of the 
Guarantors in consideration of their Guaranties. Each of the other Partners, 
or their predecessor's in interest, has previously contributed cash or 
property to the Partnership.

     3.02 ADDITIONAL CAPITAL CONTRIBUTIONS.

          (a) No Partner shall be obligated to make any Capital Contributions
     to the Partnership.

          (b) If a Guarantor makes payments to the Construction Lender pursuant
     to its obligation under the applicable Guaranty, such payment shall be
     treated as a Capital Contribution to the Partnership.

     3.03 FAILURE TO MAKE REQUIRED CONTRIBUTIONS. Any Guarantor who fails or 
refuses to make any payment to the Construction Lender required under such 
Guarantor's Guaranty by any applicable due date (including all extensions and 
cure periods) shall forfeit its Partnership Interest (but in the cases of 
Langdale and Jere Thompson, only the portion of their respective Partnership 
Interest received as consideration for their Guaranty) to the remaining 
Guarantors, who shall be entitled to receive such interest pro rata based 
upon the amount of such Guarantors' Guaranties. Such forfeiture will occur 
automatically upon such failure or refusal to pay without necessity of any 
further action.

     3.04 CAPITAL ACCOUNTS. The Partnership shall establish and maintain a
capital account ("Capital Account") for each Partner in accordance with Section
704(b) of the Code and Treasury Regulations Section 1.704-1(b)(2)(iv). Except as
otherwise provided in this Agreement, the Capital Account balance of each
Partner shall be credited (increased) by (i) the amount of cash contributed or
deemed contributed by such Partner to the capital of the Partnership, (ii) the
fair market value of property contributed or deemed contributed by such Partner
to the capital of the Partnership (net of liabilities secured by such property
that the Partnership assumes or takes subject to), (iii) such Partner's
allocable share of Partnership income and gain (or items thereof) including
income and gain exempt from federal taxation, and (iv) such Partner's share of
any increase in basis of Partnership "Section 38" property pursuant to Section
48(q) of the Code, and the Capital Account balance of each Partner shall be
debited (decreased) by (i) the amount of cash distributed to such Partner, (ii)
the fair market value of property distributed to such Partner (net of
liabilities secured by such property which the Partner assumes or takes subject
to), (iii) such Partner's share of Partnership losses, depreciation and other
deductions, including such Partner's share of expenditures of the Partnership
described in Section 705(a)(2)(B) of the Code and (iv) such Partner's share of
any


                                      6

<PAGE>

reduction in basis of Partnership "Section 38" property pursuant to Section 
48(q) of the Code. A Partner's share of any basis reduction or increase 
pursuant to Section 48(q) of the Code shall be determined in the manner 
prescribed by Treasury Regulations Section 1.46-3(f). Notwithstanding the 
foregoing, a Partner's Capital Account shall not be adjusted to reflect gain 
or loss attributable to the disposition of property contributed by such 
Partner to the extent such Partner's Capital Account reflected such inherent 
gain or loss in the property on the date of its contribution to the 
Partnership.

     3.05 PARTNER LOANS. A Partner, or an Affiliate of a Partner, may, but is 
not obligated to, loan or cause to be loaned to the Partnership such 
additional sums as the General Partner deems appropriate or necessary for the 
conduct of the Partnership's business. Loans made by a Partner, or an 
Affiliate of a Partner, shall be upon such terms and for such maturities as 
the General Partner deems reasonable in view of all the facts and 
circumstances and the repayment of which may be designated in priority to 
distributions of Cash Flow.

     3.06 OTHER MATTERS RELATING TO CAPITAL CONTRIBUTIONS.

          (a)  Loans by any Partner to the Partnership shall not be 
     considered contributions to the capital of the Partnership.

          (b)  No Partner shall be required to make contributions to the 
     capital of the Partnership except to the extent expressly provided by 
     this Article III.

          (c)  No Partner shall be entitled to withdraw, or to obtain a return 
     of, any part of his or her contribution to the capital of the 
     Partnership, or to receive property or assets other than cash in return 
     thereof, and no Partner shall be liable to any other Partner for a 
     return of his or her contributions to the capital of the Partnership, 
     except as provided in this Agreement.

          (d)  No Partner shall be entitled to priority over any other 
     Partner, either with respect to a return of his or her contributions to 
     the capital of the Partnership, or to allocations of taxable income, 
     gains, losses or credits, or to distributions, except as provided in 
     this Agreement.

          (e)  No interest shall be paid on any Partner's Capital Contributions.


     3.07 DEFICIT CAPITAL ACCOUNT BALANCES. Upon liquidation of the 
Partnership, no Limited Partner with a deficit balance in his or her Capital 
Account shall have any obligation to restore such deficit balance, or to make 
any contribution to the capital of the Partnership. Upon liquidation of the 
Partnership, the General Partner shall be obligated to contribute to the 
capital of the Partnership within ninety (90) days after the date of such 
liquidation an amount equal to the lesser of its deficit Capital Account 
balance or 1.01% of the aggregate Limited Partner Capital Contributions less 
the aggregate Capital Contributions previously made by the General Partner 
which amount shall be paid to the creditors of the Partnership or distributed 
to the other Partners in accordance with their positive Capital Account 
balances.


                                      7

<PAGE>

                                      ARTICLE IV

                       RIGHTS AND POWERS OF THE GENERAL PARTNER

     4.01 DUTIES OF GENERAL PARTNER. The General Partner shall have full, 
exclusive and complete discretion to manage and control the business and 
affairs of the Partnership, to make all decisions affecting the business and 
affairs of the Partnership, and to take all actions it deems necessary or 
appropriate to accomplish the purposes of the Partnership. The rights, powers 
and authorities of the General Partner shall include, without limitation, 
absolute authority to (i) perform all acts, make all decisions and perform 
all duties which are appropriate or necessary in conjunction with the 
fulfillment of the Partnership purposes, and (ii) negotiate, execute and 
deliver any and all documents appropriate or necessary to accomplish any of 
the foregoing. The rights, powers and authorities of the General Partner 
pursuant to this Agreement shall be liberally construed to encompass all acts 
and activities in which a Limited Partnership may engage under the act. The 
expression of any power, authority or right of the General Partner in this 
Agreement shall not limit or exclude any other power, authority or right 
which is not specifically or expressly set forth in this Agreement or the act.

     4.02 RELIANCE BY THIRD PARTIES. Notwithstanding any other provision of 
this Agreement to the contrary, no lender or purchaser, including any 
purchaser of property from the Partnership or any other person dealing with 
the Partnership, shall be required to look to the application of proceeds 
hereunder or to verify any representation by the General Partner as to the 
extent of the interest in the assets of the Partnership that the General 
Partner is entitled to encumber, sell or otherwise use, and any such lender 
or purchaser shall be entitled to rely exclusively on the representations of 
the General Partner as to its authority to enter into such financing or sale 
arrangement and shall be entitled to deal with the General Partner as to its 
authority to enter into such financing or sale arrangement and shall be 
entitled to deal with the General Partner as if it were the sole party in 
interest therein, both legally and beneficially. In no event shall any Person 
dealing with the General Partner's representative with respect to any 
business or property of the Partnership be obligated to ascertain that the 
terms of this Agreement have been complied with, or be obligated to inquire 
into the necessity or expedience of any act or action of the General Partner 
or the General Partner's representative. Every contract, agreement, deed, 
mortgage, security agreement, promissory note or other instrument or document 
executed by the General Partner or the General Partner's representative with 
respect to the business or property of the Partnership shall be conclusive 
evidence in favor of any and every Person relying thereon or claiming 
thereunder that (a) at the time of the execution and/or delivery thereof; 
this Agreement was in full force and effect, (b) such instrument or document 
was duly executed in accordance with the terms and provisions of this 
Agreement and is binding upon the Partnership, and (c) the General Partner or 
the General Partner's representative was duly authorized and empowered to 
execute to deliver any and every such instrument or document for and on 
behalf of the Partnership.

     4.03 MANAGEMENT OF BUSINESS. The General Partner shall operate and 
manage the business of the Partnership on a day-to-day basis. Notwithstanding 
the foregoing, the General Partner shall have the right, in its sole 
discretion, to employ any competent management company as it shall select to 
perform said management services.


                                      8

<PAGE>

     4.04 OPERATING RESERVE ACCOUNT. To the extent funds of the Partnership 
are sufficient therefor, the General Partner shall maintain an adequate 
reserve for operating expenses and capital expenditures as deemed necessary 
by the General Partner for the proper conduct of the business of the 
Partnership.

     4.05 PAYMENT OF COSTS AND EXPENSES. The Partnership shall be responsible 
for paying all costs and expenses of forming and continuing the Partnership, 
and conducting the business of the Partnership, including, without 
limitation, costs of utilities, costs of furniture, fixtures, equipment and 
supplies, insurance premiums, property taxes, accounting costs, legal 
expenses and office supplies. If any such costs and expenses are or have been 
paid by the General Partner, or any of its Affiliates, on behalf of the 
Partnership, then such General Partner (or its Affiliates) shall be entitled 
to be reimbursed for such payment so long as such cost or expense was 
reasonably necessary and was reasonable in amount.

     4.06 EXERCISE OF RIGHTS AND POWERS. The General Partner shall endeavor 
to operate and manage the business of the Partnership to the best of its 
ability, in a careful and prudent manner and in accordance with good industry 
practice. The authority of the General Partner to take any action required or 
permitted under the provisions of this Agreement shall in all respects be 
exercised in its sole and absolute discretion, and the General Partner shall 
be required to devote only such time to the performance of its duties and 
obligations hereunder as it shall, in its sole and absolute discretion, 
determine to be necessary or advisable. The General Partner shall be entitled 
to deal with its Affiliates in the performance of its duties and obligations 
under this Agreement, so long as the material terms and conditions of such 
dealings are not substantially different from the prevailing market terms, 
conditions and prices available from non-Affiliated third parties.

     4.07 COMPENSATION. Except as otherwise expressly provided in this 
Agreement, the General Partner and its Affiliates shall not be entitled to 
receive any compensation from the Partnership. This Section 4.07 does not in 
any way limit the General Partner's right to reimbursement pursuant to 
Section 4.05.

     4.08 LIABILITY. The General Partner shall endeavor to perform its duties 
under this Agreement with ordinary prudence and in a manner reasonable under 
the circumstances. The General Partner shall not be liable to the Partnership 
or the Limited Partners for any loss or liability caused by any act, or by 
the failure to do any act, unless such loss or liability arises from the 
General Partner's intentional misconduct, gross negligence or fraud. In no 
event shall the General Partner be liable by reason of a mistake in judgment 
made in good faith, or action or lack of action based on the advice of legal 
counsel. Further, the General Partner shall in no event be liable for its 
failure to take any action unless it is specifically directed to take such 
action under the terms of this Agreement.

     4.09 INDEMNIFICATION. Upon the determInation as set forth in Section 
11.06 of the Act that such indemnification is permissible under Section 11.02 
of the Act, the Partnership (but not the Limited Partners) hereby indemnifies 
and holds harmless any person or entity who is or was a General Partner (and 
its Affiliates) against any and all losses, costs, expenses (including 
reasonable attorneys' fees), penalties, taxes, fines, settlements, damages 
and judgments resulting from the fact


                                      9

<PAGE>

the General Partner was, is or is threatened to be named a defendant or 
respondent in a Proceeding because such person was or is a General Partner in 
the Partnership, even if such losses, costs, expenses etc. were the result of 
the General Partner's own negligence. This indemnification shall only be 
effective if the General Partner (i) acted in good faith, (ii) reasonably 
believed that in instances that the General Partner was acting in its 
official capacity that its conduct was in the Partnership's best interest and 
in all other instances that the General Partner's conduct was not opposed to 
the Partnership's best interests, and (iii) in a criminal proceeding, had no 
cause to believe its conduct was unlawful. Notwithstanding the foregoing, 
this indemnification shall in no event be applicable to a Proceeding in which 
the General Partner has been found to be liable for intentional misconduct, 
gross negligence or fraud in the performance of the General Partner's duty to 
the Partnership or the Limited Partners.

     4.10.  TAX MATTERS PARTNER.

            (a) The General Partner is hereby designated as the "tax matters
     partner" of the Partnership (as defined in the Code) and is authorized and
     required to represent the Partnership (at the Partnership's expense) in
     connection with all examinations of the Partnership's affairs by tax
     authorities, including resulting administrative and judicial proceedings,
     and to expend Partnership finds for professional services and costs
     associated therewith. The Limited Partners agree to cooperate with the
     General Partner and to do or refrain from doing any or all things
     reasonably required by the General Partner to conduct such proceedings.

            (b)  The General Partner is authorized to:

                (i)    enter into a settlement agreement with the Service with
          respect to any tax audit or judicial review, in which agreement the
          General Partner may expressly state that the agreement will bind all
          Partners;

                (ii)   file a petition for judicial review of a final
          administrative adjustment pursuant to section 6226 of the Code;

                (iii)  intervene in any action brought by any other Partner
          for judicial review of a final administrative adjustment;

                (iv)   file a request for an administrative adjustment with
          the Service at any time and, if any part of the request is not allowed
          by the Service, to file a petition for judicial review with respect to
          the request; and

                (v)    take any other action on behalf of the Partners or the
          Partnership in connection with any administrative or judicial tax
          proceeding to the extent permitted by applicable law or regulations.

          (c)   The Partnership will reimburse the General Partner for all
     expenses incurred by it in connection with any administrative or judicial
     proceeding with respect to the tax liabilities of the Partners.


                                     10

<PAGE>

     4.11.  GUARANTY OF DEBT; GUARANTY AND COMMITMENT FEES.

            (a)  The Guarantors shall severally guaranty the Construction Loan
     in the following amounts:
<TABLE>
                 <S>                           <C>
                 Jere Thompson                 $1,000,000
                 Hayden                         2,000,000
                 Jodie Thompson                 1,000,000
                 Florida                        1,000,000
                 Langdale                       3,000,000
</TABLE>

          If, for any reason, the Guarantors make payments to the 
     Construction Lender in satisfaction of all or a portion of their 
     obligation under their Guarantees, then each Guarantor making such 
     payment shall receive an additional Partnership Interest in the 
     Partnership as a Limited Partner equal to 3.00% (after issuance) for 
     each $1 million paid to the Construction Lender pursuant to such 
     Guaranty, pro rated for lesser amounts. The additional Partnership 
     Interest issuable to the Guarantors pursuant to this Section 4.11(a) 
     shall be derived solely out of the Partnership Interests of the Limited 
     Partners, including the Partnership Interests of the Guarantors existing 
     as of the date immediately prior to the effective date of this 
     Agreement, other than from the Partnership Interests of Jodie Thompson, 
     Hayden and Florida. In accordance with Section 3.02(b), amounts paid 
     pursuant to the Guaranties will be treated as Capital Contributions to 
     the Partnership.

          (b) The Partnership shall pay to the Guarantors the Guaranty Fee. 
     The Guaranty Fee shall be payable quarterly in arrears commencing 
     September 30, 1996. The accrued but unpaid Guaranty Fee shall accrue 
     interest at a rate equal to 12% per annum commencing from and after July 
     1, 1997. Such interest rate will increase 2% per annum commencing on 
     July 1, 1998 and each subsequent anniversary date.

          (c) The Partnership shall pay the Commitment Fee to each Guarantor. 
     The accrued but unpaid Commitment Fee shall accrue interest at a rate 
     equal to 12% per annum commencing from and after July 1, 1997. Such 
     interest rate will increase 2% per annum commencing on July 1, 1998 and 
     each subsequent anniversary date.

     4.12 CONSTRUCTION MANAGEMENT.  CapRock shall manage the construction and 
development of the Network on behalf of the Partnership. The Partnership 
shall pay to CapRock a fee in an amount equal to the sum of (i) 4% of the 
actual cost of constructing the entire Network payable monthly at a minimum 
of $15,000 per month commencing on February 1, 1996 and ending on the date 
the final payment is made to C&B Associates by the Partnership under all of 
its contracts for the construction of the entire Network and (ii) 5% of the 
excess of the projected costs of construction and capital expenditures as set 
forth in the budget submitted to the Construction Lender ($11,403,845), less 
the actual construction costs and capital expenditures incurred in the 
construction and start-up of the Network which amount is payable on the date 
of the last payment due under (i) above, and is being paid as an inducement 
to minimize the cost of the Network's construction and start-up. The 
management of the construction and development of the Network shall be 
conducted


                                     11

<PAGE>

pursuant to that certain Construction Management Agreement to be entered into 
between the Partnership and CapRock.

     4.13.  NETWORK ADMINISTRATION. The Partnership shall retain CapRock 
Communications Corp., a Texas corporation, to operate and manage the Network 
in accordance with that certain Management and Administration Agreement to be 
entered into between the Partnership and CapRock Communications Corp.


                                      ARTICLE V

                               LIMITED PARTNER MATTERS

      5.01  LIMITATION OF LIABILITY. No Limited Partner shall be bound by, or 
personally liable for, obligations or liabilities of the Partnership beyond 
the amount of his or its required contributions to the capital of the 
Partnership, and no Limited Partner shall be required to contribute any 
capital to the Partnership in excess of the contributions for which he or it 
is personally liable for under Article III.

     5.02   MANAGEMENT. No Limited Partner shall participate in the operation 
or management of the business of the Partnership, or transact any business 
for or in the name of the Partnership, nor shall any Limited Partner have any 
right or power to sign for or bind the Partnership in any manner. The right 
of the Limited Partners to consent to and approve of certain matters under 
the provisions of this Agreement shall not be deemed a participation in the 
operation and management of the business of the Partnership, or the exercise 
of control over the Partnership's affairs.

     5.03   CONSENTS. Any action requiring the consent or approval of the 
Limited Partners under the provisions of this Agreement shall be taken only 
if the consent or approval of the requisite number of Limited Partners is 
evidenced by written instrument executed by such Limited Partners.

     5.04   POWER OF ATTORNEY

            (a) Each Limited Partner hereby irrevocably severally appoints and
     constitutes the General Partner, its successors and assigns hereunder as
     its true and lawful attorney-in-fact, with full power and authority, on its
     behalf and in its name, to execute, acknowledge, swear to, deliver and,
     where appropriate, file in such offices and places as may be required by
     law:

                (i)   the Certificate, and any amendment thereto; and

                (ii)  any amendment to this Agreement upon compliance with
          Article VIII, Article IX or Section 11.01.

          (b) The power of attorney granted by the Limited Partners to the
     General Partner under paragraph (a) above is a special power coupled with
     an interest and is irrevocable, and may be exercised by any Person who at
     the time of exercise is a General Partner of the


                                     12

<PAGE>

     Partnership. Such power of attorney shall survive the death or legal 
     disability of a Limited Partner ant any Transfers or abandonment of its 
     Partnership Interest, or its withdrawal from the Partnership.

     5.05 DEATH, BANKRUPTCY, ETC. In no event shall the death, incompetency,
bankruptcy, insolvency or other incapacity of a Limited Partner operate to
dissolve the Partnership.

                                      ARTICLE VI

                            ALLOCATIONS AND DISTRIBUTIONS

     6.01   ALLOCATION OF NET INCOME AND LOSS FROM OPERATIONS. Net income and 
loss for each fiscal year from Operations shall be determined for financial 
accounting purposes in accordance with the method of accounting used for 
federal income tax purposes and the books and records of the Partnership. 
Except as provided in Sections 6.03 and 6.07(b), income, gain, loss and 
deduction shall be allocated among the Partners as set forth below.

          (a)  Net income and gain shall be allocated to the Partners as
     follows:

               (i)     First, to the Partners pro rata in accordance with, 
          and in an amount equal to the difference between (A) the sum of the 
          Cash Flow from Operations and Major Capital Events then 
          distributable plus the aggregate amount of Cash Flow from 
          Operations and Major Capital Events previously distributed to the 
          Partners pursuant to Section 6.02(a), over (b) the aggregate amount 
          of net income and gain previously allocated to such Partners 
          pursuant to this Section 6.01(a)(i);

               (ii)    Next, to the Partners pro rata in accordance with, and 
          in an amount equal to, the difference between the aggregate net 
          loss and deduction previously allocated to the partners pursuant to 
          Section 6.01(b) over the aggregate amount of net income and gain
          previously allocated to such Partners pursuant to this Section 
          6.01(a)(ii);

               (iii)   Next, to the Partners pro rata in accordance with, and 
          in an amount equal to the difference between (A) the sum of the 
          Cash Flow from Operations and Major Capital Events then 
          distributable plus the aggregate amount of Cash Flow from 
          Operations and Major Capital Events previously distributed to the 
          Partners pursuant to Section 6.02(c), over (b) the aggregate amount 
          of net income and gain previously allocated to such Partners 
          pursuant to this Section 6.01(a)(iii); and

                (iv)   Thereafter, 1% to the General Partner, 19.5% to 
          Thompson, 4.5% to Langdale and the remainder among the Partners 
          (including Thompson and Langdale) pro rata in accordance with their 
          Partnership Interests.

          (b)  Net loss and deduction shall be allocated to the Partners as
     follows:


                                     13

<PAGE>

                (i)   First, to the Partners pro rata in accordance with, and
          in an amount equal to, their positive Capital Account balances; and

                (ii)  Thereafter, to Partners pro rata in accordance with
          their Partnership Interests.

            (c)  Notwithstanding anything to the contrary in Section 6.01(b), 
     any item of net loss or deduction that is attributable to a partner 
     nonrecourse debt must be allocated to the Partner that bears the 
     economic risk of loss for such debt as determined under Code Sections 
     704 and 752, and the Treasury Regulations thereunder. If more than one 
     Partner bears the economic risk of loss for a partner nonrecourse debt, 
     any net loss attributable to such debt must be allocated among such 
     Partners in accordance with the ratios in which the Partners share the 
     economic risk of loss for such partner nonrecourse debt.

     6.02   DISTRIBUTIONS OF CASH FLOW FROM OPERATIONS AND MAJOR CAPITAL 
EVENTS. The General Partner shall distribute Cash Flow from Operations and 
Major Capital Events when available to the Partners. Notwithstanding the 
frequency or amounts of distributions, Cash Flow shall be distributed as 
follows:

            (a)  First, to the Guarantors pro rata in accordance with their 
     Unpaid Preferred Return, in such amount and until such time as each such 
     Guarantor's Unpaid Preferred Return has been reduced to zero;

            (b)  Next, to the Guarantors pro rata in accordance with their 
     Unreturned Capital Contributions, in such amount and until such time as 
     each such Guarantor's Unreturned Capital Contributions has been reduced 
     to zero;

            (c)  Next, to the Partners pro rata in accordance with their 
     Partnership Interests until such time as the Guaranties of each 
     Guarantor other than Langdale have been released in their entirety by 
     the Construction Lender; and

            (d)  Thereafter, 1% to the General Partner, 19.5% to Thompson, 4.5%
     to Langdale and the remainder among the Partners (including Thompson and 
     Langdale) pro rata in accordance with their Partnership Interests.

     6.03   LIMITATIONS ON ALLOCATIONS.

            (a)  MINIMUM GAIN CHARGEBACK. Notwithstanding any provision of 
     this Article VI, if there is a net decrease in Partnership minimum gain 
     during any fiscal year or other period, prior to any other allocation 
     pursuant hereto, each Partner shall be specially allocated items of 
     Partnership income and gain for such year (and, if necessary, subsequent 
     years) in an amount and manner required by Treasury Regulation Sections 
     1.704-1T(b)(4)(iv)(e) and (h) and Section 1.704-2. Notwithstanding any 
     provision of this Article VI, if there is a net decrease in partner 
     nonrecourse debt minimum gain, any Partner with a share of that partner 
     nonrecourse debt minimum gain as of the beginning of such year shall be 
     allocated items of


                                     14

<PAGE>

     income and gain for the year (and, if necessary, for succeeding years) 
     equal to that Partner's share of the net decrease in the partner 
     nonrecourse debt minimum gain, as provided in Treasury Regulation 
     Section 1.704-2(i)(4).

            (b)  QUALIFIED INCOME OFFSET. Any Partner who unexpectedly 
     receives an adjustment, allocation or distribution described in Treasury 
     Regulation Section 1.704-1(b)(2) (ii)(d)(4), (5) or (6) that causes or 
     increases a negative balance in its Capital Account beyond the sum of 
     the amount of such Partner's obligation to restore its deficit Capital 
     Account plus its share of minimum gain shall be allocated items of 
     income and gain sufficient to eliminate such increase or negative 
     balance caused thereby, as quickly as possible, to the extent required 
     by such Treasury Regulation.

            (c)  GROSS INCOME ALLOCATION. If any Partner has a deficit 
     Capital Account at the end of any Partnership fiscal year which is in 
     excess of the sum of (i) the amount such Partner is obligated to restore 
     pursuant to any provision of this Agreement and (ii) the amount such 
     Partner is deemed to be obligated to restore pursuant to Treasury 
     Regulation Section 1.704-2, each such Partner shall be specially 
     allocated items of Partnership income and gain in the amount- of such 
     excess as quickly as possible, provided that an allocation pursuant to 
     this Section 6.03(c) shall be made only if and to the extent that such 
     Partner would have a deficit Capital Account in excess of such sum after 
     all other allocations provided for in this Article VI have been made as 
     if this Section 6.03(c) were not in this Agreement.

            (d)  SECTION 704(b) LIMITATION. Notwithstanding any other 
     provision of this Agreement to the contrary, no allocation of any item 
     of income or loss shall be made to a Partner if such allocation would 
     not have "economic effect" pursuant to Treasury Regulation Section 
     1.704-1(b)(2)(ii) or otherwise be in accordance with its interest in the 
     Partnership within the meaning of Treasury Regulation Sections 
     1.704-1(b)(3) and 1.704-2. To the extent an allocation cannot be made to 
     a Partner due to the application of this Section 6.03(d), such 
     allocation shall be made to the other Partner(s) entitled or required to 
     receive such allocation hereunder.

            (e)  CURATIVE ALLOCATIONS. Any allocations of items of income, 
     gain, or loss pursuant to Sections 6.03(a)-(d) shall be taken into 
     account in computing subsequent allocations pursuant to this Article VI, 
     so that the net amount of any items so allocated and the income, losses 
     and other items allocated to each Partner pursuant to this Article VI 
     shall, to the extent possible, be equal to the net amount that would 
     have been allocated to each Partner had no allocations ever been made 
     pursuant to Sections 6.03(a)-(d).

            (f)  MINIMUM ALLOCATIONS TO GENERAL PARTNER. If at any time the 
     allocation provisions of this Agreement do not result in the General 
     Partners being allocated at least one percent of all material items of 
     income, gain, loss, deduction or credit, the General Partner shall be 
     allocated so much of those items as will cause it at all times during the
     existence of the Partnership to be allocated at least one percent of 
     those items.


                                     15

<PAGE>

     6.04   DISTRIBUTIONS UPON LIQUIDATION OF PARTNERSHIP.

            (a)  Upon liquidation of the Partnership the assets of the 
     Partnership shall be distributed no later than the later of 90 days 
     after the date of such liquidation or the end of the Partnership s 
     taxable year in which the liquidation occurs and shall be applied in the 
     following order of priority:

                 (i)     To the payment of debts and liabilities of the 
            Partnership (including amounts owed to Partners or former 
            Partners);

                 (ii)    Unless inconsistent with Treasury Regulation Section 
            1.704-1(b)(2)(ii)(b), or any successor provision, to set up any 
            reserves which the General Partner deems reasonably necessary for 
            contingent or unforeseen liabilities or obligations of the 
            Partnership arising out of or in connection with the business of 
            the Partnership; and

                 (iii)   After all Capital Account adjustments for the 
            Partnership s taxable year in which the liquidation occurs 
            (including without limitation adjustments required under Treasury 
            Regulation Section 1.704-1(b)(2)(iv)(e), relating to 
            distributions in kind), to the Partners in accordance with each 
            Partner's positive Capital Account balance in the same order as 
            distributions are made in Section 6.02.

            (b)  If a transfer of an interest in the Partnership results in a 
     termination of the Partnership for federal income tax purposes under 
     Section 708(b)(1)(B) of the Code (or any successor provision thereto), 
     Section 6.04(a) shall not apply and a Partner's portion of the 
     constructive liquidating distribution of the Partnership s assets that 
     is deemed to occur under Treasury Regulation Section 1.708-1(b)(1)(iv) 
     (or any similar or successor provision) shall be determined in 
     accordance with the Capital Accounts of the Partners as determined after 
     taking into account all Capital Account adjustments for the 
     Partnership's taxable year ending on the date of such termination.

     6.05   LIQUIDATION OF PARTNERS INTEREST.  Except as may otherwise be 
required in this Agreement, if a Partner's interest in the Partnership is to 
be liquidated, liquidating distributions shall be made in accordance with the 
positive Capital Account balance of such Partner, as determined after taking 
into account all Capital Account adjustments for the Partnership's taxable 
year during which such liquidation occurs, by the end of the taxable year, or 
if later, within ninety (90) days after the date of such liquidation. If a 
Partner's interest is to be liquidated, it has a negative Capital Account 
balance and it is obligated to restore some or all of its negative Capital 
Account upon liquidation of the Partnership pursuant to Section 3.06, then 
such Partner shall, by the end of the taxable year or, if earlier, within 
ninety (90) days of the date of such liquidation, contribute cash to the 
Partnership in an amount equal to its negative Capital Account or such lesser 
amount as provided in Section 3.06. Where a Partner's interest is to be 
liquidated by a series of distributions, such Partner's interest shall not be 
considered liquidated until the final distribution has been made. For 
purposes of this Section 6.06, a liquidation of a Partner's interest in the 
Partnership means the termination of the


                                     16

<PAGE>

Partner s entire interest in the Partnership by means of a distribution or 
series of distributions to the Partner by the Partnership.

     6.06   IN-KIND DISTRIBUTIONS.

            (a)  Prior to a distribution of property (other than cash and 
     other than in complete liquidation of the Partnership or a Partner's 
     interest in the Partnership), the Capital Accounts of the Partners shall 
     be adjusted to reflect the manner in which the unrealized income, gain, 
     loss and deduction inherent in such property (that has not previously 
     been reflected in the Capital Accounts), would be allocated among the 
     Partners if there were a taxable disposition of the property on the date 
     of distribution.

            (b)  If the distribution of property (other than cash) is to a 
     Partner in complete liquidation of the Partner's interest in the 
     Partnership or in liquidation of the Partnership, prior to such 
     distribution, the Capital Accounts of all the Partners shall be adjusted 
     to reflect the manner in which the unrealized income, gain, loss and 
     deduction inherent in all the Partnership's property (that has not 
     previously been reflected in the Capital Accounts) would be allocated 
     among the Partners if there was a taxable disposition of all such 
     property on the date of the liquidating distribution.

            (c)  If any assets of the Partnership are distributed to the 
     Partners in kind, the Partners shall own and hold the same as tenants in 
     common.

     6.07   ADDITIONAL TAX ALLOCATION PROVISIONS.

            (a)  For income tax purposes, allocations of income and loss (and 
     items thereof) shall be made in accordance with the foregoing 
     allocations of income, gain and loss for financial purposes.

            (b)  Notwithstanding anything to the contrary contained herein, 
     items of income, gain, loss and deduction with respect to property, 
     other than cash, contributed to the Partnership by a Partner or with 
     respect to an adjustment to the Partners' Capital Accounts to reflect a 
     revaluation of the Network, shall be allocated among the Partners so as 
     to take into account the variation between the basis of the property to 
     the Partnership and its fair market value at the time of contribution 
     or, in the case of a revaluation of the Network, the variation between 
     the basis of the Network to the Partnership and its fair market value as 
     of the date of revaluation, as provided in Section 704(c) of the Code 
     and Regulations thereunder and Treasury Regulations Section 
     1.704-1(b)(2)(iv)(g).

            (c)  As between a Partner who has transferred all or part of its
     interest in the Partnership and its transferee, all items of income, gain,
     deduction and loss, for any year shall be apportioned on the basis of the
     number of days in each such year that each was the holder of such interest
     (making any adjustments necessary to comply with the provisions of Section
     706(d)(2) of the Code), without regard to the results of the Partnership's
     operations during the period before and after the date of such transfer,
     provided that if both the


                                      17

<PAGE>

     transferor and transferee consent thereto a special closing of the books 
     shall be had as of the effective date of such transfer and the 
     apportionment of items of income and gain, and deduction and loss, shall 
     be made on the basis of actual operating results. Notwithstanding the 
     above, gain or loss resulting from a Major Capital Event or a 
     Liquidating Event shall be allocated only to those persons who are 
     Partners as of the date on which such transaction is consummated.


                                     ARTICLE VII

                                    FISCAL MATTERS

     7.01   FISCAL YEAR. The fiscal year of the Partnership shall be as 
required under Section 706 of the Code.

     7.02   BOOKS AND RECORDS. The General Partner shall keep, or cause to be 
kept, at the expense of the Partnership, full and accurate books and records 
of all transactions of the Partnership in accordance with accepted accounting 
principles, consistently applied. Among such books and records the General 
Partner shall keep:

            (a)  A current list of the following items:


                 (i)     the name and mailing address of each Partner,
          separately identifying in alphabetical order the General Partners and
          the Limited Partners:


                 (ii)    the last known street address of the business or
          residence of each General Partner; and


                 (iii)   the Partnership Interest of each Partner.


            (b)  Copies of the Partnership's federal, state and local tax 
     returns for each of the Partnership's six most recent tax years;

          (c)  A copy of this Agreement, the Certificate, all amendments and 
     restatements and executed copies of any powers of attorney under which 
     this Agreement, the Certificate and any and all Amendments or 
     restatements thereto have been executed. All of such books and records 
     shall, at all times, be maintained at the principal place of business of 
     the Partnership and the Limited Partners shall have the right to inspect 
     and copy any of them, at their own expense, during normal business hours.

     7.03   REPORTS AND STATEMENTS.

            (a)  Within 90 days after the end of each fiscal year of the 
     Partnership, the General Partner shall, at the expense of the 
     Partnership, cause to be delivered to each Limited Partner such 
     financial statements and such other information as the General Partner 
     believes to be

                                      18

<PAGE>

     necessary for the Limited Partners to be advised of the financial status 
     and results of operations of the Partnership.

            (b)  The General Partner shall report to the Limited Partners any 
     significant development materially adversely affecting the Partnership, 
     its business, property or assets, as soon as practicable following the 
     occurrence of such development.

          (c)  The General Partner shall provide to the Guarantors a copy of 
     the financial statements which the Partnership provides to the 
     Construction Lender, contemporaneously with the delivery of such 
     documents to the Construction Lender, and such other information which 
     is provided to the Limited Partners.

     7.04   AUDIT. A Limited Partner may require an audit of the books and 
records of the Partnership to be conducted at any time (but not more 
frequently than once each calendar year). Any such audit so required shall be 
conducted by auditors selected by such Limited Partner at the expense of the 
Partnership.

     7.05   TAX RETURNS. The General Partner shall cause to be prepared and 
delivered to the Partners on or before seventy-five days following the end of 
each fiscal year, at the expense of the Partnership, all federal and any 
required state and local income tax returns for the Partnership for the 
preceding fiscal year. In the event the Partnership's income tax returns are 
audited, the General Partner shall retain, at the expense of the Partnership, 
accountants and other professionals to participate in such audit in order to 
contest assertions by the auditing agent that may be materially adverse to 
the Partners.

     7.06   BANK ACCOUNTS. The General Partner, in the name of the 
Partnership, shall open and maintain a special bank account or accounts in a 
bank or savings and loan association, the deposits of which are insured by an 
agency of the United States government, in which shall be deposited all 
fluids of the Partnership. There shall be no commingling of the property and 
assets of the Partnership with the property and assets of any other party.

     7.07   TAX ELECTIONS. The General Partner shall be entitled to determine 
all Federal income tax elections available to the Partnership.


                                  ARTICLE VIII
                                    TRANSFERS

     8.01   RESTRICTION ON TRANSFERS. Except as expressly permitted under the 
terms and provisions of this Article VIII, no Partnership Interest shall be 
Transferred without the written consent of the General Partner.

     8.02   PERMITTED SALES AFTER RIGHT OF FIRST REFUSAL IS GIVEN. Except for 
a Transfer from one Partner to another in which case this Section does not 
apply, if a Partner receives an offer (the "Offer") for the purchase of all 
or a part of such Partner's Partnership Interest (the "Offered


                                      19

<PAGE>

Interest"), then the Partner who received such Offer (the "Selling Partner") 
shall, if it wishes to accept the Offer, promptly forward a true and correct 
copy thereof to the other Partners (whether one or more, the "Non-Selling 
Partner") within ten (10) days of the date of the Offer. The Non-Selling 
Partner shall have the exclusive right and option for sixty (60) days 
following the receipt of said Offer (unless extended as provided in the last 
paragraph hereof) to purchase all, but not less than all, of the Offered 
Interest on the terms and conditions set forth in the Offer. The Non-Selling 
Partner shall exercise its option to purchase the Offered Interest by actual 
delivery to the Selling Partner, within the aforesaid sixty (60) day period, 
written notice of such election. The Non-Selling Partner shall be deemed to 
have elected not to purchase the Offered Interest if it fails to timely 
provide written acceptance. Each Non-Selling Partner who elects to so 
purchase the Offered Interest pursuant to the Offer (the "Electing Partner") 
shall have the right to purchase that proportion of the Offered Interest 
which the amount such Electing Partner elects to purchase bears to the total 
amount which the Electing Partners elected to purchase. The Electing Partner 
shall be obligated to close no later than ninety (90) days after the date of 
the Offer.

     If the Non-Selling Partner does not elect to purchase all of the Offered 
Interest, the Selling Partner may sell the Offered Interest; provided, 
however, that the sale (i) shall not be made at a price lower than the price 
offered to the Non-Selling Partner, (ii) is not made to any person other than 
the original offeror, (iii) is on the same terms and conditions as those 
specified in the Offer, and (iv) is consummated within ninety (90) days after 
the lapse of all options arising in connection with the offer.

     If the offeror, terms or conditions of the proposed sale are changed or 
such Offered Interest has not been sold prior to the lapse of the aforesaid 
ninety (90) day period, the Selling Partner must make a new offer, pursuant 
to the procedures in this Section 8.02, to the Non-Selling Partner prior to 
selling such Offered Interest. If the Non-Selling Partner elects to purchase 
all of the Offered Interest, then the closing of said purchase shall take 
place at the office of the Partnership.

     Notwithstanding anything else to the contrary in this Section 8.02, if 
the Selling Partner is Thompson or a member of the Thompson Family, then 
Thompson and the Thompson Family shall have the first and exclusive right to 
acquire the Offered Interest prior to any other Partner having such right. If 
neither Thompson nor a member of the Thompson Family elects to purchase all 
of the Offered Interest within sixty (60) days following receipt of the 
Offer, then the remaining Partners shall have the right for twenty (20) days 
following such sixty (60) day period to acquire the Offered Interest.

     8.03   PERMITTED TRANSFERS. Notwithstanding anything else in this 
Agreement to the contrary:

            (a)  a Partner may Transfer all or any portion of a Partnership 
     Interest to another Partner without the consent of any Partner; and

          (b)  a Guarantor may Transfer all or any portion of the Partnership 
     Interest which it receives in exchange for its Guaranty, or pursuant to 
     Section 3.03 or 4.11, to an Affiliate without the consent of any Partner.


                                     20

<PAGE>

     8.04   ASSUMPTION BY TRANSFEREE. Any transferee to whom all or any part 
of a Partnership Interest may be Transferred pursuant to this Agreement shall 
take such Partnership Interest subject to all of the terms and conditions of 
this Agreement and shall not be considered to have title thereto until said 
transferee shall have accepted and assumed the terms and conditions of this 
Agreement by a written agreement to that effect delivered to the other 
Partners, at which time such transferee shall be admitted as a substitute 
Partner and shall succeed to all rights of its transferor except as such 
rights may be otherwise limited by other provisions of this Agreement.

     8.05   COST OF TRANSFERS. The transferor and, if it fails or refuses to 
do so, then the transferee, of any Partnership Interest shall reimburse the 
Partnership for all costs incurred by the Partnership resulting from any 
Transfer.

     8.06   EFFECT OF ATTEMPTED DISPOSITION IN VIOLATION OF THIS AGREEMENT. 
Any attempted Transfer of any Partnership Interest in breach of this 
Agreement shall be null and void and of no effect whatever.


                                      ARTICLE IX

                        RESIGNATION, WITHDRAWAL AND REMOVAL OF
                  GENERAL PARTNER: ADMISSION OF NEW GENERAL PARTNER

     9.01   VOLUNTARY RESIGNATION OR WITHDRAWAL OF THE GENERAL PARTNER. The 
General Partner may not withdraw its interest in the Partnership, Transfer 
its interest to any Person or admit any Person as a substitute General 
Partner except as provided in Article VIII or this Article IX.

     9.02   SUBSTITUTE AND ADDITIONAL GENERAL PARTNERS. To the extent 
permitted under Texas law, the General Partner may at any time designate 
additional Persons to be General Partners, whose interest in the Partnership 
shall be such as shall be agreed upon by the General Partner and such 
additional General Partners, so long as the Partnership Interest of the 
Limited Partners shall not be affected thereby.

     9.03   ADMISSION OF A SUCCESSOR GENERAL PARTNER. Any successor Person 
shall be admitted as a General Partner of the Partnership if the following 
terms and conditions are satisfied:

            (a)  The successor Person shall have accepted and assumed all the 
     terms and provisions of this Agreement and the Shareholders' Agreement 
     governing the General Partner;

            (b)  If the successor Person is a corporation, it shall have 
     provided counsel for the Partnership with a certified copy of a 
     resolution of its Board of Directors authorizing it to become a General 
     Partner under the terms and conditions of this Agreement; and

            (c)  The successor Person shall have executed this Agreement and 
     such other documents or instruments as may be required or appropriate in 
     order to effect the admission of such Person as a General Partner.


                                      21

<PAGE>

                                   ARTICLE X

                                  DISSOLUTION

     10.01  DISSOLUTION.

            (a)  It is the intention of the Partners that the business of the 
Partnership be continued by the Partners, or those remaining, pursuant to the 
provisions of this Agreement, notwithstanding the occurrence of any event 
which would result in a statutory dissolution of the Partnership pursuant to 
the laws of the State of Texas, and no Partner shall be released or relieved 
of any duty or obligation hereunder by reason thereof; provided, however, 
that the business of the Partnership shall be terminated, its affairs 
wound-up and its property and assets distributed in liquidation on the 
earlier to occur of:

                 (i)    December 31, 2025;

                 (ii)   a determination by the General Partner that the
            business of the Partnership should be terminated;

                 (iii)  the bankruptcy or insolvency of the Partnership;

                 (iv)   subject to the provisions of paragraph (b) below, the
            death, incompetency, bankruptcy, insolvency, withdrawal or removal
            from the Partnership of the last remaining General Partner;

                 (vi)   the date upon which a Liquidating Event occurs, and all
            payments have been received;

                 (vii)  entry of a decree of judicial dissolution; or

                 (viii) the date voting control of the General Partner is no
            longer held by Thompson, Langdale, a family member of either one or
            an Affiliate of either one.

     For purposes of this Agreement, bankruptcy shall be deemed to have occurred
     when the party in question files a petition under any section or chapter of
     the Federal Bankruptcy Code, as amended, or becomes subject to an order for
     relief under Title 11 of the United States Code Annotated or is declared
     bankrupt or insolvent in a state bankruptcy or insolvency hearing.

            (b)  Upon the occurrence of any event set forth in subparagraph (iv)
     of paragraph (a) above with respect to the last remaining General Partner,
     the business of the Partnership shall be continued pursuant to the
     provisions of this Agreement if, within a period of 90 days from the date
     of such occurrence, each of the Limited Partners shall elect in writing
     that it be so continued and shall designate one or more parties to be
     admitted to the Partnership as a General Partner. Any such party shall upon
     admission to the Partnership succeed to all of the rights and powers of a
     General Partner hereunder, provided that the former General 


                                       22

<PAGE>

     Partner shall retain and be entitled to its share of profits, losses,
     distributions, and capital associated with the General Partner's
     Partnership Interest.

     10.02  WIND-UP OF AFFAIRS.  As expeditiously as possible following the 
occurrence of an event giving rise to a termination of the business of the 
Partnership, the General Partner (or a special liquidator who may be 
appointed by the Limited Partners if the termination results from a 
circumstance described in Section 10.01 (a)(iv) above relative to the General 
Partners) shall wind-up the affairs of the Partnership, sell its property and 
assets for cash at the highest price reasonably obtainable, distribute the 
proceeds in accordance with Section 6.04 in liquidation of the Partnership 
and file a certificate of cancellation with the Secretary of State of Texas.

                                  ARTICLE II

                                 MISCELLANEOUS

     11.01  AMENDMENTS.  Unless otherwise expressly provided herein, this 
Agreement may not be amended without the written consent of the General 
Partner and a Majority in Interest of the Limited Partners.

     11.02  OTHER ACTIVITIES.  Any Partner may engage or possess an interest 
in other business ventures of every nature and description, independently or 
with others, including, without limitation, the acquisition, construction, 
ownership, leasing, operation and management of projects similar to the 
Partnership's business), and neither the Partnership nor any of the other 
Partners shall have any right by virtue of this Agreement in and to such 
other ventures or to the income or property derived therefrom.

     11.03  PARTITION.  No Partner shall be entitled to a partition of the 
Network or any other property or assets of the Partnership, notwithstanding 
any provision of law to the contrary.

     11.04  NOTICES.  Any notice required or permitted to be delivered to any 
Partner under the provisions of this Agreement shall be deemed delivered, 
whether actually received or not, when deposited in a United States Postal 
Service depository, postage prepaid, registered or certified, return receipt 
requested, and addressed to the Partner at the address specified on the 
signature pages hereof, or such other address as shall be specified by 
written notice delivered to the General Partner.

     11.05  PROVISIONS SEVERABLE.  Every provision of this Agreement is 
intended to be severable and, if any term or provision hereof is illegal or 
invalid for any reason whatsoever, such illegality or invalidity shall not 
affect the validity of the remainder of this Agreement.

     11.06  COUNTERPARTS.  This Agreement, and any amendments hereto, may be 
executed in counterparts, each of which shall be deemed an original, and such 
counterparts shall constitute but one and the same instrument.


                                       23

<PAGE>

     11.07  HEADINGS.  The headings of the various Sections are intended 
solely for convenience of reference, and shall not be deemed or construed to 
explain, modify or place any construction upon the provisions hereof.

     11.08  SUCCESSORS AND ASSIGNS.  This Agreement and any amendments hereto 
shall be binding upon and, to the extent expressly permitted by the 
provisions hereof, shall inure to the benefit of the Partners and their 
respective heirs, legal representatives, successors and assigns.

     11.09  APPLICABLE LAW.  THIS AGREEMENT SHALL BE GOVERNED BY AND 
CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF TEXAS.

     IN WITNESS WHEREOF, the Partners have executed this Agreement this 31 
day of October, 1996 effective for all purposes as of July 1, 1996.


                                       GENERAL PARTNER:

                                       CAPROCK SYSTEMS, INC.
                                       a Texas corporation


                                       By: /s/ Jere W. Thompson, Jr.
                                           ---------------------------
                                           Name: Jere W. Thompson, Jr.
                                           Its:  President


                                           Address: 13455 Noel Road
                                                    Suite 1925
                                                    Dallas, Texas 75240


                                       24

<PAGE>

                        LIMITED PARTNER SIGNATURE PAGE

     This Limited Partner Signature Page is attached to, and made a part of, 
that certain Second Amended and Restated Agreement of Limited Partnership of 
CapRock Fiber Network, Ltd. By execution hereof, the undersigned agrees to be 
bound by, and perform in accordance with, such Partnership Agreement.


                                       LIMITED PARTNER:


                                       /s/ Michael D. Thompson
                                       ---------------------------
                                       Name: Michael D. Thompson


                                       Address:   3037 Milton
                                                  Dallas, TX 75205

                                       Facsimile: (214) 841-6590


                                       25

<PAGE>

                        LIMITED PARTNER SIGNATURE PAGE

     This Limited Partner Signature Page is attached to, and made a part of, 
that certain Second Amended and Restated Agreement of Limited Partnership of 
CapRock Fiber Network, Ltd. By execution hereof, the undersigned agrees to be 
bound by, and perform in accordance with, such Partnership Agreement.


                                       LIMITED PARTNER:


                                       /s/ Patrick J. Thompson
                                       -----------------------------
                                       Name: Patrick J. Thompson


                                       Address:   5534 Northmoor Dr.
                                                  Dallas, TX 75230

                                       Facsimile: (817) 251-0796


                                       26

<PAGE>

                        LIMITED PARTNER SIGNATURE PAGE

     This Limited Partner Signature Page is attached to, and made a part of, 
that certain Second Amended and Restated Agreement of Limited Partnership of 
CapRock Fiber Network, Ltd. By execution hereof, the undersigned agrees to be 
bound by, and perform in accordance with, such Partnership Agreement.


                                       LIMITED PARTNER:


                                       /s/ Margaret T. Nelson
                                       ---------------------------
                                       Name: Margaret T. Nelson


                                       Address:   4425 Hyer
                                                  Dallas, 75205

                                       Facsimile:
                                                  ----------------


                                       27

<PAGE>

                        LIMITED PARTNER SIGNATURE PAGE

     This Limited Partner Signature Page is attached to, and made a part of, 
that certain Second Amended and Restated Agreement of Limited Partnership of 
CapRock Fiber Network, Ltd. By execution hereof, the undersigned agrees to be 
bound by, and perform in accordance with, such Partnership Agreement.


                                       LIMITED PARTNER:


                                       /s/ Kimberly T. Thornton
                                       ------------------------------
                                       Name: Kimberly T. Thornton


                                       Address:   P.O. Box 1345
                                                  Telluride, CO 81435

                                       Facsimile: (970) 728-5809


                                       28

<PAGE>

                        LIMITED PARTNER SIGNATURE PAGE

     This Limited Partner Signature Page is attached to, and made a part of, 
that certain Second Amended and Restated Agreement of Limited Partnership of 
CapRock Fiber Network, Ltd. By execution hereof, the undersigned agrees to be 
bound by, and perform in accordance with, such Partnership Agreement.


                                       LIMITED PARTNER:


                                       /s/ Christopher D. Thompson
                                       -----------------------------
                                       Name: Christopher D. Thompson


                                       Address:   3121 Amherst
                                                  Dallas, TX 75225

                                       Facsimile:
                                                  ------------------


                                       29

<PAGE>

                      LIMITED PARTNER SIGNATURE PAGE

     This Limited Partner Signature Page is attached to, and made a part of,
that certain Second Amended and Restated Agreement of Limited Partnership of
CapRock Fiber Network, Ltd. By execution hereof, the undersigned agrees to be
bound by, and perform in accordance with, such Partnership Agreement.




                              LIMITED PARTNER:

                              /s/ David E. Thompson
                              ---------------------------------
                              Name:     David E. Thompson

                              Address:  4409 Shoal Creek Blvd.
                                        -----------------------
                                        Austin TX 78756
                                        -----------------------

                              Facsimile: (512) 467-2191
                                        -----------------------



                                    30
<PAGE>


                    LIMITED PARTNER SIGNATURE PAGE

     This Limited Partner Signature Page is attached to, and made a part of,
that certain Second Amended and Restated Agreement of Limited Partnership of
CapRock Fiber Network, Ltd. By execution hereof, the undersigned agrees to be
bound by, and perform in accordance with, such Partnership Agreement.




                              LIMITED PARTNER:
                              The Florida Company, a Texas Corporation

                              By: /s/ Joe C. Thompson, Jr.
                                  -----------------------------
                              Name: Joe C. Thompson, Jr.
                                   ----------------------------
                              Its: President
                                   ----------------------------

                              Address:  2960 Anode Lane
                                        -----------------------
                                        Dallas, TX 75220
                                        -----------------------

                              Facsimile: 214 / 357-3490
                                        -----------------------



                               31


<PAGE>


                      LIMITED PARTNER SIGNATURE PAGE

     This Limited Partner Signature Page is attached to, and made a part of,
that certain Second Amended and Restated Agreement of Limited Partnership of
CapRock Fiber Network, Ltd. By execution hereof, the undersigned agrees to be
bound by, and perform in accordance with, such Partnership Agreement.



                              LIMITED PARTNER:


                              /s/ Joe C. Thompson, Jr.
                              ---------------------------------
                              Name:     Joe C. Thompson, Jr

                              Address:  2960 Anode Lane
                                        -----------------------
                                        Dallas, TX 75220
                                        -----------------------

                              Facsimile: 214 / 357-3490
                                        -----------------------



                           32
<PAGE>


                      LIMITED PARTNER SIGNATURE PAGE

     This Limited Partner Signature Page is attached to, and made a part of,
that certain Second Amended and Restated Agreement of Limited Partnership of
CapRock Fiber Network, Ltd. By execution hereof, the undersigned agrees to be
bound by, and perform in accordance with, such Partnership Agreement.




                              LIMITED PARTNER:

                              THE HAYDEN COMPANY
                              a Texas corporation

                              By: /s/ John P. Thompson
                                  -----------------------------
                              Name: John P. Thompson
                                   ----------------------------
                              Its: President
                                  -----------------------------

                              Address: Two Turtle Creek Village
                                       ------------------------
                                       3838 Oak Lawn Ave., Suite 1850
                                       ------------------------
                                       Dallas, TX 75219-4519
                                       ------------------------

                              Facsimile: (214) 443-9299
                                        -----------------------



                              33
<PAGE>


                      LIMITED PARTNER SIGNATURE PAGE

     This Limited Partner Signature Page is attached to, and made a part of,
that certain Second Amended and Restated Agreement of Limited Partnership of
CapRock Fiber Network, Ltd. By execution hereof, the undersigned agrees to be
bound by, and perform in accordance with, such Partnership Agreement.




                              LIMITED PARTNER:

                              /s/ Peggy Thompson
                              ---------------------------------
                              Name:     Peggy Thompson

                              Address: 4217 Armstrong Parkway
                                       ------------------------
                                       Dallas, TX 75205
                                       ------------------------

                              Facsimile: 
                                        -----------------------



                                   34
<PAGE>


                      LIMITED PARTNER SIGNATURE PAGE

     This Limited Partner Signature Page is attached to, and made a part of,
that certain Second Amended and Restated Agreement of Limited Partnership of
CapRock Fiber Network, Ltd. By execution hereof, the undersigned agrees to be
bound by, and perform in accordance with, such Partnership Agreement.




                              LIMITED PARTNER:


                              /s/ Mark Langdale
                              ---------------------------------
                              Name:     Mark Langdale

                              Address:  5950 Berkshire #990
                                        -----------------------
                                        Dallas, TX 75225
                                        -----------------------

                              Facsimile: 214-891-3175
                                        -----------------------



                                 35
<PAGE>



                     LIMITED PARTNER SIGNATURE PAGE

     This Limited Partner Signature Page is attached to, and made a part of,
that certain Second Amended and Restated Agreement of Limited Partnership of
CapRock Fiber Network, Ltd. By execution hereof, the undersigned agrees to be
bound by, and perform in accordance with, such Partnership Agreement.




                              LIMITED PARTNER:


                              /s/ Jere W. Thompson, Sr.
                              ---------------------------------
                              Name:     Jere W. Thompson, Sr.

                              Address: Two Turtle Creek Village
                                       ------------------------
                                       3838 Oak Lawn Ave. Suite 1850
                                       ------------------------
                                       Dallas, TX 75219-4519
                                       ------------------------

                              Facsimile: 214 / 443-9299
                                        -----------------------



                                   36
<PAGE>


                      LIMITED PARTNER SIGNATURE PAGE

     This Limited Partner Signature Page is attached to, and made a part of,
that certain Second Amended and Restated Agreement of Limited Partnership of
CapRock Fiber Network, Ltd. By execution hereof, the undersigned agrees to be
bound by, and perform in accordance with, such Partnership Agreement.




                              LIMITED PARTNER:


                              /s/ Jere W. Thompson, Jr.
                              ---------------------------------
                              Name:     Jere W. Thompson, Jr.

                              Address: 13455 Noel Road, Ste 1925
                                       ------------------------
                                       Dallas, TX 75240
                                       ------------------------

                              Facsimile: (872) 788-4243
                                        -----------------------



                                    37

<PAGE>

                                   EXHIBIT "A"
                        
                        THE PARTNERS; PARTNERSHIP INTERESTS
<TABLE>
<CAPTION>
The General Partner:                   Partnership Interests:
     <S>                                   <C>
     CapRock Systems, Inc.                   1.00%

The Limited Partners:

     Michael D. Thompson                     1.55%
     Patrick J. Thompson                     1.55%
     Margaret T. Nelson                      1.55%
     Kimberly T. Thornton                    1.55%
     Christopher D. Thompson                 1.55%
     David.E. Thompson                       1.55%
     The Florida Company                     2.67%
     Joe C. Thompson, Jr.                    2.67%
     The Hayden Company                      5.34%
     Peggy Thompson                          6.22%
     Jere W. Thompson, Sr.                   8.87%
     Mark Langdale                          46.79%
     Jere W. Thompson, Jr.                  17.14%
                                           ------
                                           100.00%
</TABLE>


                                      38
<PAGE>

                                 AMENDMENT NO. 1 TO THE
                              SECOND AMENDED AND RESTATED
                           AGREEMENT OF LIMITED PARTNERSHIP
                            OF CAPROCK FIBER NETWORK, LTD.

     This Amendment No. 1 (this "AMENDMENT") to the Second Amended and 
Restated Agreement of Limited Partnership (the "AGREEMENT") of CapRock Fiber 
Network, Ltd., a Texas limited partnership (the "PARTNERSHIP"), is entered 
into by and among CapRock Systems, Inc., a Texas corporation as the general 
partner of the Partnership (the "GENERAL PARTNER"), and Michael D. Thompson, 
Patrick J. Thompson, Margaret T. Nelson, Kimberly T Thornton, Christopher D. 
Thompson, David E. Thompson, The Florida Company, a Texas corporation, Joe C. 
Thompson, Jr., The Hayden Company, a Texas corporation, Peggy Thompson, Jere 
W. Thompson, Sr., Mark Langdale, Jere W. Thompson, Jr., and Dan Jones 
(individually, a "LIMITED PARTNER" and collectively, the "LIMITED PARTNERS"). 
The General Partner and the Limited Partners are sometimes individually 
referred to herein as a "PARTNER" and sometimes collectively referred to 
herein as the "PARTNERS".

                                      BACKGROUND

     The Partners entered into that certain Agreement of Limited Partnership of
CapRock Fiber Network, Ltd., which was amended effective as of May 31, 1993, and
further amended by the terms of the Agreement effective as of July 1, 1996.

     The Partners recognize the dedicated service, leadership, and other
contributions of Dan Jones ("JONES") to the Partnership and, therefore, desire
to amend the Agreement, effective as of September 1, 1997, to admit Jones as a
Limited Partner upon the terms and conditions of this Amendment.

     Jones desires to become a Limited Partner upon the terms and conditions of
this Amendment and the Agreement.

     THEREFORE, in consideration of the foregoing, and other good and valuable
consideration, the receipt and sufficiency of which all parties acknowledge, the
parties hereto agree as follows:

                              AMENDMENT TO THE AGREEMENT

     1.   The definition of "Limited Partners" contained in SECTION 1.01 of the
Agreement is hereby deleted and replaced in its entirety by the following:

          "Limited Partners" shall mean Michael D. Thompson, Patrick J.
     Thompson, Margaret T. Nelson, Kimberly T. Thornton, Christopher D.
     Thompson, David E. Thompson, The Florida Company, Joe C. Thompson, Jr., The
     Hayden Company, Peggy Thompson, Jere W. Thompson, Sr., Mark Langdale, Jere
     W. Thompson, Jr. and Dan Jones.

<PAGE>

     2.   SECTION 2.01(b) is hereby deleted and replaced in its entirety by the
following:

          "(b) As of the effective date of this Agreement, Hayden, Florida and
     Jodie Thompson are admitted to the Partnership as Limited Partners."

     3.   SECTION 2.01 is hereby amended by adding the following subsection (c):

          "(c) As of the effective date of Amendment No 1 to this Agreement, Dan
     Jones is hereby admitted to the Partnership as a Limited Partner, and the
     Partnership Interests of the Partners shall be as set forth in Exhibit "A"
     to the Amendment No. 1 to this Agreement."

     4.   The Agreement is hereby further amended by adding the following
ARTICLE XII:

                                    "ARTICLE XII
                                 MERGER AND EXCHANGE

          12.01     MERGER.  The General Partner, on behalf of and in the name
     of the Partnership, may adopt a plan of merger pursuant to which the
     Partnership may merge with one or more domestic or foreign partnerships or
     other entities.

          12.02     EXCHANGE.  The General Partner, on behalf of and in the name
     of the Partnership, may adopt a plan of exchange by which a domestic or
     foreign partnership, or other entity acquires all of the outstanding
     Partnership Interests of the Partnership in exchange for cash or securities
     of the acquiring domestic or foreign partnership."

     5.   Each of the remaining articles, sections, terms, and provisions of the
Agreement shall remain in full force and effect, and shall be enforceable
against the Partners in accordance with their terms.

     6.   Capitalized terms not otherwise defined in this Amendment shall have
the meanings assigned to such terms in the Agreement.

     IN WITNESS WHEREOF, the Partners have executed this Amendment to be
effective the 1st day of September, 1997.


                     [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]

<PAGE>


Dated to be effective as of September 1, 1997.

                         GENERAL PARTNER:

                         CAPROCK SYSTEMS, INC.,
                         a Texas corporation



                         By:       /s/ Jere Thompson, Jr.
                            ---------------------------------------------
                         Name:     Jere Thompson, Jr.
                         Title:    President

<PAGE>

                            LIMITED PARTNER SIGNATURE PAGE


     This Limited Partner Signature Page is attached to, and made a part of,
that certain Amendment No. 1 to the Second Amended and Restated Agreement of
Limited Partnership of CapRock Fiber Network, Ltd. By execution hereof, the
undersigned agrees to be bound by, and perform in accordance with, the Second
Amended and Restated Agreement of Limited Partnership of CapRock Fiber Network,
Ltd. as amended by Amendment No. 1.

     Dated to be effective as of September 1, 1997.

                              LIMITED PARTNER:


                              /s/ Michael D. Thompson
                              ---------------------------
                                  Michael D. Thompson

<PAGE>

                            LIMITED PARTNER SIGNATURE PAGE

     This Limited Partner Signature Page is attached to, and made a part of,
that certain Amendment No. 1 to the Second Amended and Restated Agreement of
Limited Partnership of CapRock Fiber Network, Ltd. By execution hereof, the
undersigned agrees to be bound by, and perform in accordance with, the Second
Amended and Restated Agreement of Limited Partnership of CapRock Fiber Network,
Ltd. as amended by Amendment No. 1.

     Dated to be effective as of September 1, 1997.

                              LIMITED PARTNER:


                              /s/ Patrick J. Thompson
                              --------------------------------
                                  Patrick J. Thompson

<PAGE>

                            LIMITED PARTNER SIGNATURE PAGE

     This Limited Partner Signature Page is attached to, and made a part of,
that certain Amendment No. 1 to the Second Amended and Restated Agreement of
Limited Partnership of CapRock Fiber Network, Ltd. By execution hereof, the
undersigned agrees to be bound by, and perform in accordance with, the Second
Amended and Restated Agreement of Limited Partnership of CapRock Fiber Network,
Ltd. as amended by Amendment No. 1.

     Dated to be effective as of September 1, 1997.

                              LIMITED PARTNER:


                              /s/ Margaret T. Nelson
                              --------------------------------
                                  Margaret T. Nelson

<PAGE>

                            LIMITED PARTNER SIGNATURE PAGE

     This Limited Partner Signature Page is attached to, and made a part of,
that certain Amendment No. 1 to the Second Amended and Restated Agreement of
Limited Partnership of CapRock Fiber Network, Ltd. By execution hereof, the
undersigned agrees to be bound by, and perform in accordance with, the Second
Amended and Restated Agreement of Limited Partnership of CapRock Fiber Network,
Ltd. as amended by Amendment No. 1.

     Dated to be effective as of September 1, 1997.

                              LIMITED PARTNER:


                              /s/ Kimberly T. Thornton
                              -----------------------------------
                                  Kimberly T. Thornton

<PAGE>

                            LIMITED PARTNER SIGNATURE PAGE

     This Limited Partner Signature Page is attached to, and made a part of,
that certain Amendment No. 1 to the Second Amended and Restated Agreement of
Limited Partnership of CapRock Fiber Network, Ltd. By execution hereof, the
undersigned agrees to be bound by, and perform in accordance with, the Second
Amended and Restated Agreement of Limited Partnership of CapRock Fiber Network,
Ltd. as amended by Amendment No. 1.

     Dated to be effective as of September 1, 1997.

                              LIMITED PARTNER:


                              /s/ Christopher D. Thompson
                              ------------------------------------------
                                  Christopher D. Thompson

<PAGE>

                            LIMITED PARTNER SIGNATURE PAGE

     This Limited Partner Signature Page is attached to, and made a part of,
that certain Amendment No. 1 to the Second Amended and Restated Agreement of
Limited Partnership of CapRock Fiber Network, Ltd. By execution hereof, the
undersigned agrees to be bound by, and perform in accordance with, the Second
Amended and Restated Agreement of Limited Partnership of CapRock Fiber Network,
Ltd. as amended by Amendment No. 1.

     Dated to be effective as of September 1, 1997.

                              LIMITED PARTNER:


                              /s/ David E. Thompson 
                              -------------------------------------
                                  David E. Thompson

<PAGE>

                            LIMITED PARTNER SIGNATURE PAGE

     This Limited Partner Signature Page is attached to, and made a part of,
that certain Amendment No. 1 to the Second Amended and Restated Agreement of
Limited Partnership of CapRock Fiber Network, Ltd. By execution hereof, the
undersigned agrees to be bound by, and perform in accordance with, the Second
Amended and Restated Agreement of Limited Partnership of CapRock Fiber Network,
Ltd. as amended by Amendment No. 1.

     Dated to be effective as of September 1, 1997.

                              LIMITED PARTNER:


                              /s/ Joe C. Thompson, Jr.
                              ----------------------------------------
                                  Joe C. Thompson, Jr.


<PAGE>

                            LIMITED PARTNER SIGNATURE PAGE

     This Limited Partner Signature Page is attached to, and made a part of,
that certain Amendment No. 1 to the Second Amended and Restated Agreement of
Limited Partnership of CapRock Fiber Network, Ltd. By execution hereof, the
undersigned agrees to be bound by, and perform in accordance with, the Second
Amended and Restated Agreement of Limited Partnership of CapRock Fiber Network,
Ltd. as amended by Amendment No. 1.

     Dated to be effective as of September 1, 1997.

                              LIMITED PARTNER:


                              /s/ Jere W. Thompson, Jr.
                              ------------------------------------------
                                  Jere W. Thompson, Jr.

<PAGE>

                            LIMITED PARTNER SIGNATURE PAGE

     This Limited Partner Signature Page is attached to, and made a part of,
that certain Amendment No. 1 to the Second Amended and Restated Agreement of
Limited Partnership of CapRock Fiber Network, Ltd. By execution hereof, the
undersigned agrees to be bound by, and perform in accordance with, the Second
Amended and Restated Agreement of Limited Partnership of CapRock Fiber Network,
Ltd. as amended by Amendment No. 1.

     Dated to be effective as of September 1, 1997.

                              LIMITED PARTNER:


                              /s/ Margaret Thompson
                              -------------------------------------
                                   Margaret Thompson

<PAGE>

                            LIMITED PARTNER SIGNATURE PAGE

     This Limited Partner Signature Page is attached to, and made a part of,
that certain Amendment No. 1 to the Second Amended and Restated Agreement of
Limited Partnership of CapRock Fiber Network, Ltd. By execution hereof, the
undersigned agrees to be bound by, and perform in accordance with, the Second
Amended and Restated Agreement of Limited Partnership of CapRock Fiber Network,
Ltd. as amended by Amendment No. 1.

     Dated to be effective as of September 1, 1997.

                              LIMITED PARTNER:


                              /s/ Jere W. Thompson, Sr
                              ---------------------------------------
                                  Jere W. Thompson, Sr

<PAGE>

                            LIMITED PARTNER SIGNATURE PAGE

     This Limited Partner Signature Page is attached to, and made a part of,
that certain Amendment No. 1 to the Second Amended and Restated Agreement of
Limited Partnership of CapRock Fiber Network, Ltd. By execution hereof, the
undersigned agrees to be bound by, and perform in accordance with, the Second
Amended and Restated Agreement of Limited Partnership of CapRock Fiber Network,
Ltd. as amended by Amendment No. 1.

     Dated to be effective as of September 1, 1997.

                              LIMITED PARTNER:


                              /s/ Dan Jones
                              ----------------------------------
                                  Dan Jones

<PAGE>

                            LIMITED PARTNER SIGNATURE PAGE

     This Limited Partner Signature Page is attached to, and made a part of,
that certain Amendment No. 1 to the Second Amended and Restated Agreement of
Limited Partnership of CapRock Fiber Network, Ltd. By execution hereof, the
undersigned agrees to be bound by, and perform in accordance with, the Second
Amended and Restated Agreement of Limited Partnership of CapRock Fiber Network,
Ltd. as amended by Amendment No. 1.

     Dated to be effective as of September 1, 1997.

                              LIMITED PARTNER:

                              THE FLORIDA COMPANY,
                              a Texas corporation


                              By:/s/ Joe C. Thompson, Jr.
                                 -----------------------------------------
                              Name:  Joe C. Thompson, Jr.
                              Title: President

<PAGE>

                            LIMITED PARTNER SIGNATURE PAGE

     This Limited Partner Signature Page is attached to, and made a part of,
that certain Amendment No. 1 to the Second Amended and Restated Agreement of
Limited Partnership of CapRock Fiber Network, Ltd. By execution hereof, the
undersigned agrees to be bound by, and perform in accordance with, the Second
Amended and Restated Agreement of Limited Partnership of CapRock Fiber Network,
Ltd. as amended by Amendment No. 1.

     Dated to be effective as of September 1, 1997.

                              LIMITED PARTNER:

                              THE HAYDEN COMPANY,
                              a Texas corporation


                              By: /s/ John P. Thompson
                                 ----------------------------------
                              Name:  John P. Thompson
                              Title: President


<PAGE>

                            LIMITED PARTNER SIGNATURE PAGE

     This Limited Partner Signature Page is attached to, and made a part of,
that certain Amendment No. 1 to the Second Amended and Restated Agreement of
Limited Partnership of CapRock Fiber Network, Ltd. By execution hereof, the
undersigned agrees to be bound by, and perform in accordance with, the Second
Amended and Restated Agreement of Limited Partnership of CapRock Fiber Network,
Ltd. as amended by Amendment No. 1.

     Dated to be effective as of September 1, 1997.

                              LIMITED PARTNER:


                              /s/ Mark Langdale
                              ---------------------------------------
                                  Mark Langdale

<PAGE>

                AMENDMENT NO. 1 TO THE SECOND AMENDED AND RESTATED
          AGREEMENT OF LIMITED PARTNERSHIP OF CAPROCK FIBER NETWORKS LTD.

                                      EXHIBIT A

<TABLE>
<CAPTION>
GENERAL PARTNER:                      PARTNERSHIP INTEREST:

     <S>                                    <C>
     CapRock Systems, Inc.                   1.72375%


LIMITED PARTNERS:

     Mark Langdale                          38.99919%
     The Hayden Company                      3.94493%
     Joe C. Thompson, Jr                     1.97246%
     The Florida Company                     1.97246%
     Dan B. Jones                            1.50000%
     Jere W. Thompson, Sr.                   6.55635%
     Margaret D. Thompson                    4.58389%
     Michael D. Thompson                     1.14597%
     Jere W. Thompson, Jr.                  31.87113%
     Patrick J. Thompson                     1.14597%
     Margaret T. Nelson                      1.14597%
     Kimberly T. Thornton                    1.14597%
     Christopher D. Thompson                 1.14597%
     David E. Thompson                       1.14597%

Total:                                     100.00000%

</TABLE>

<PAGE>

                                CONTRIBUTION AGREEMENT
                                    AND AMENDMENT


     This Contribution Agreement (the "Agreement") is entered into by and 
among Jere W, Thompson, Jr. ("Jere"), Greenway Holdings, L.P., a Texas 
limited partnership (the "Partnership"), and for a limited purpose, CapRock 
Systems, Inc. ("CapRock Systems"), a Texas corporation and the general 
partner of CapRock Fiber Network, Ltd., a Texas limited Partnership ("CapRock 
Fiber") and a majority in interest of the limited partners in CapRock Fiber.

                                  R E C I T A L S:

     A.   Jere desires to contribute his entire ownership interest (the "CapRock
Fiber Interest") in CapRock Fiber to the Partnership in exchange for a 1%
general partnership interest and a 93.7289% limited partnership interest in the
Partnership (the "Partnership Interests"). The limited partnership interest will
be issued one-half to Jere, and the balance to his wife, Carolyn C. Thompson.

     B.   By execution of this Agreement, CapRock Systems and a majority in
interest of the limited partners evidence their consent to the contribution of
the CapRock Fiber Interest and amend the Second Amended and Restated Agreement
of Limited Partnership of CapRock Fiber Network, Ltd. (the "CapRock Fiber
Agreement") to reflect the change in partner.

                                 A G R E E M E N T:

     IT IS THEREFORE AGREED:

     1.   CONTRIBUTION. For valuable consideration, the receipt and sufficiency
of which are hereby acknowledged, Jere hereby agrees to contribute, and does
hereby contribute, to the Partnership, and the Partnership hereby agrees to
accept, and does hereby accept, the CapRock Fiber Interest.

     2.   CONSIDERATION. For and in consideration of the contribution of the
CapRock Fiber Interest by Jere to the Partnership, the Partnership hereby issues
to Jere and Carolyn the Partnership Interests.

     3.   AMENDMENT. By execution of this Agreement, CapRock Systems and a
majority in interest of the limited partners in CapRock Fiber, in accordance
with Section 11.01 of the CapRock Fiber Agreement, hereby amend the CapRock
Fiber Agreement to admit the Partnership to CapRock Fiber pursuant to this
Agreement. Exhibit "A" to the CapRock Fiber Agreement is amended and restated in
the manner set forth on Exhibit "A" attached to this Agreement.

     4.   AGREEMENT OF THE PARTNERSHIP. The Partnership hereby accepts, assumes
and agrees to be bound by, and to perform in accordance with, all of the terms
and provisions of the CapRock Fiber Agreement.

     5.   MISCELLANEOUS. This Agreement (i) shall be binding upon and shall
inure to the

<PAGE>

benefit of the parties hereto and their respective heirs, representatives, 
administrators, successors and assigns; (ii) may not in any way be altered, 
amended, modified or upgraded except by an instrument in writing signed by 
the parties hereto; (iii) and the rights of the parties hereto shall be 
governed by and construed in accordance with the laws of the State of Texas; 
and (iv) may be executed in multiple counterparts, each of which shall 
constitute an original.

          IN WITNESS WHEREOF, this Agreement is executed as of the 29th day of
December, 1997.

                              THE PARTNERSHIP;

                              GREENWAY HOLDINGS, L,P,
                              a Texas limited partnership



                              By: /s/ Jere W. Thompson, Jr.
                                 ------------------------------------
                                   Jere W. Thompson, Jr.
                              Its: General Partner

                                  /s/ Jere W. Thompson, Jr.
                                 ------------------------------------
                                   Jere W. Thompson, Jr.



     By execution hereof, the undersigned, who constitute the general partner
and a majority in interest of the limited partners in CapRock Fiber, consent to
the contribution of the Partnership interests to the Partnership, and the
amendment of the CapRock Fiber Agreement.

CapRock Systems, Inc.



/s/ Jere W. Thompson, Jr.                     /s/ Jere W. Thompson, Jr.
-------------------------------------         ----------------------------------
    Jere W. Thompson, Jr., President              Jere W. Thompson, Jr.


/s/ Mark Langdale
-------------------------------------
    Mark Langdale



                                       2
<PAGE>

                                     EXHIBIT "A"

                         THE PARTNERS: PARTNERSHIP INTERESTS
<TABLE>
<CAPTION>
The General Partner:               Partnership Interests:
     <S>                                    <C>
     CapRock Systems, Inc                    1.72375%

The Limited Partners:

     Michael D. Thompson                     1.14597%
     Patrick J. Thompson                     1.14597%
     Margaret T. Nelson                      1.14597%
     Kimberly T. Thornton                    1.14597%
     Christopher D. Thompson                 1.14397%
     David E. Thompson                       1.14597%
     The Florida Company                     1.97246%
     Joe C. Thompson, Jr.                    1.97246%
     The Hayden Company                      3.94493%
     Peggy Thompson                          4.58389%
     Jere W. Thompson, Sr.                   6.55635%
     Mark Langdale                          38.99919%
     Greenway Holdings, L.P.                31.87113%
     Dan Jones                               1.50000%
                                           ---------
                                           100.00000%
</TABLE>

                                       3