Document:

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                            ALAMOSA OPERATIONS, INC.
                             4403 Brownfield Highway
                              Lubbock, Texas 79407

Dated as of October 18, 2000

Roberts Tower Company
Address: 1408 North Kingshighway, Suite 300
St. Louis, Missouri 63113
Attn: Michael V. Roberts

Re: Loan Agreement

Dear Mr. Roberts:

     The undersigned, Roberts Tower Company ("BORROWER"), a corporation duly
organized, existing, and in good standing under the laws of the State of
Missouri, is an affiliate of Roberts Wireless Communications, L.L.C., a limited
liability company duly organized, existing, and in good standing under the laws
of the State of Missouri ("RWC"), which has entered into an Agreement and Plan
of Reorganization (the "MERGER AGREEMENT") pursuant to which RWC will merge (the
"PARENT MERGER") with and into Alamosa Holdings, Inc. ("SUPERHOLDINGS")
simultaneously with the merger (the "SUBSIDIARY MERGER," together with the
Parent Merger, the "MERGERS") of a wholly-owned subsidiary of Superholdings with
and into Alamosa PCS Holdings, Inc., a Delaware corporation ("ALAMOSA").

     In connection with the anticipated Parent Merger, Borrower has requested
that Alamosa Operations, Inc., a Delaware corporation (in its capacity as Lender
hereunder, "LENDER"), extend credit to Borrower to enable Borrower to borrow as
of and after the date of this Agreement a principal amount not to exceed
$15,000,000, only for the purposes of repaying all amounts owed by the Roberts
(defined below ) under that certain loan agreement, dated June 30, 2000 as
relates to the Borrower's operations, between the Roberts and Lender, and
funding the construction of wireless telecommunications towers related to RWC
from the date hereof through the consummation of the Mergers (the "MERGER
DATE"). Lender has advised Borrower that Lender is willing to advance such funds
to Borrower upon the terms and subject to the conditions set forth in this
letter agreement (this "AGREEMENT"). In consideration for the above premises and
the mutual promises and covenants herein contained, Borrower and Lender agree as
follows:

     1. Loan. On the terms and subject to the conditions hereinafter set forth,
Lender agrees to lend to Borrower, in multiple advances (each an "ADVANCE") to
be made before the Maturity Date (defined below), the sum of up to $15,000,000
(the "LOAN"). The parties hereto acknowledge and agree that as of November 7,
2000, Advances in the aggregate amount of $9,063,437 have been made under this
Agreement.

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     2. Manner of Borrowing.

     (a) Notice of Borrowing. Whenever Borrower desires that Lender makes an
Advance after October 18, 2000, Borrower shall (i) give Lender a request (a
"NOTICE OF BORROWING") signed by Borrower for an Advance on or before 10:00 a.m.
(Dallas, Texas time) two days before the requested Advance is to be funded, (ii)
specify in the Notice of Borrowing the aggregate amount, requested date, and the
intended use of the Advance, (iii) attach to the Notice of Borrowing all unpaid
third-party vendor invoices submitted which the Borrower requests be paid from
the proceeds of such Advance and (iv) certify that the representations and
warranties contained in each of the Loan Documents (defined below) are true in
all material respects as though made on the date of the Notice of Borrowing. The
invoices submitted with any Notice of Borrowing shall only be invoices for
required goods and services provided by third-party vendors for the construction
of wireless telecommunications towers related to RWC from the date hereof (the
"APPROVED INVOICES").

     (b) Minimum Advances; Number of Advances. Each Advance hereunder shall be
in a minimum amount of $1,000,000, and no more than five (5) Advances each
calendar month may be requested or funded.

     (c) Funding. Subject to the terms and conditions in this Agreement, if
Lender, in its sole discretion, approves the Notice of Borrowing (which approval
shall not be unreasonably withheld), not later than 2:00 p.m., Dallas, Texas
time, on the date specified, Lender shall make the requested Advance (reduced by
the amount of any invoices that are not Approved Invoices) available to either
the Borrower on behalf of the vendors or, at the exclusive option of the Lender,
the vendors directly, at Lender's offices in Lubbock, Texas, the amount of the
Approved Invoices for such vendors submitted with such Notice of Borrowing in
immediately available funds. Borrower agrees that any Approved Invoices
submitted with a Notice of Borrowing may be paid directly by Lender's personnel,
at the exclusive option of the Lender, from the amount of the requested Advance.

     3. Promissory Note, Interest, and Payments.

     (a) Note. The Loan shall be evidenced by a promissory note in the form of
EXHIBIT A, duly executed by Borrower (together with any renewals and extensions
thereof, the "NOTE"), dated the date hereof, in the principal amount of
$15,000,000 and payable to the order of Lender.

     (b) Interest Rate. Before the occurrence of an Event of Default, each
Advance shall bear interest at a rate per annum, calculated from day to day and
computed from the date of advance until repaid, equal to the lesser of (i) the
maximum lawful rate under applicable law (the "MAXIMUM RATE") or (ii) 12% ("LOAN
INTEREST RATE"). Any past-due principal debt and all past-due interest accruing
thereon shall bear interest from maturity (stated or by acceleration) at a rate
per annum equal to the lesser of (i) the Maximum Rate or (ii) 17% per annum.

     (c) Payments.

          (i) Interest. Interest on the unpaid principal of the Loan shall be
     due and payable on the earlier of (A) March 31, 2001, (B) the Merger Date
     or (C) the effective date of any acceleration of any of the Obligation
     (defined below) (the "MATURITY DATE").

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          (ii) Principal. The entire unpaid principal balance of the Loan,
     including all accrued but unpaid interest thereon, shall be due and payable
     on the Maturity Date.

          (iii) Fees. (A) On the Maturity Date, Borrower agrees to pay to Lender
     a fee equal to 3% of the aggregate amount of all the Advances made to
     Borrower to and including the Maturity Date. In the event that a firm
     commitment for alternative funding, sufficient to cover for all Obligations
     (defined below) owed to Lender by Borrower, is obtained by Borrower on or
     before the later of (x) the 10th business day after Lender effectuates a
     substitution of collateral sufficient to cause the release of liens under
     the DLJ Loan Agreement (as hereinafter defined) on the assets transferred
     by RWC to Borrower as contemplated by Section 4.16 of the Merger Agreement
     or (y) November 30, 2000 (the later of (x) or (y) being the "COMMITMENT
     DATE") and all Obligations owed to Lender are paid in full on or before the
     15th day following the Commitment Date, then the payment of the fees
     described above shall be waived.

               (B) In the event, however, that any Obligation under this
          Agreement is outstanding at January 10, 2001, on the Maturity Date,
          Borrower agrees to pay to Lender an additional fee equal to 3% of the
          aggregate amount of all the Advances made to Borrower to and including
          the Maturity Date.

          (iv) Assignment of Membership Interests. (A) If (x) the Mergers are
     not consummated, and (y) the Loan, all accrued unpaid interest thereon, all
     fees, and all other sums due from Borrower to Lender under this Agreement
     and the other Loan Documents (collectively, the "OBLIGATION") are not paid
     in full, then Michael V. Robert and Steven C. Roberts (the "ROBERTS") shall
     cause Roberts Wireless Holdings, LLC to assign, transfer, and convey to
     Lender, without recourse, within ninety (90) days after the date of a
     written notice delivered by Lender to RWC advising RWC that the Merger
     Agreement is being terminated and that the Mergers will not be consummated,
     all or a portion of its membership interests in RWC so that Lender shall
     own, in addition to any other membership interests in RWC that Lender may
     already own or have the right to own under any other agreement with RWC,
     Roberts or others, on a fully diluted basis, 10% of the total membership
     interests in RWC (the "10% INTEREST"), free and clear of all liens and
     encumbrances, other than the pledge of and lien on such interests to secure
     the obligations under the loan agreement, dated as of September 8, 1999,
     between RWC and Lucent Technologies, Inc., assignor of all of its rights
     and obligations under such loan agreement to DLJ Capital Funding, Inc. (the
     "DLJ LOAN AGREEMENT"). Such obligation of the Roberts (x) is joint and
     several, (y) is evidenced by the Agreement to Assign Membership Interests
     (the "ASSIGNMENT AGREEMENT") in the form of EXHIBIT B and (z) provided that
     if the fair market value of the 10% Interest , as such fair market value is
     determined in accordance with the provisions of clause (B) below, is
     determined to be equal to or greater than the Obligation then the 10%
     Interest shall replace the obligation of Borrower to repay the Obligation
     and, when the 10% Interest is assigned to Lender, then Borrower shall have
     no further obligation under this Agreement. In case, however, that the fair
     market value of the 10% Interest is determined to be less than the
     Obligation, then the fair market value of the 10% Interest shall be applied
     towards the payment of the Obligation.

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               (B) Lender and Borrower shall each select an investment banker to
          determine the fair market value of the 10% Interest. The investment
          bankers shall take into account the usual factors for determining the
          value of a minority interest in a private company. The investment
          bankers shall cooperate with each other to complete and agree upon the
          fair market value of the 10% Interest no later than 30 days following
          the assignment of the 10% Interest. In the event that the two
          investment bankers can not agree upon the fair market value of the 10%
          Interest within the 30-day period, the two investment bankers shall
          select a mutually acceptable, neutral and qualified investment banker
          (the "NEUTRAL INVESTMENT BANKER"). All relevant documentation and
          information shall be submitted to the Neutral Investment Banker who
          shall resolve the dispute within 10 days after submission of the
          dispute and supporting documentation. The decision of the Neutral
          Investment Banker shall be final and binding upon Lender and Borrower,
          each of whom shall bear one-half of the cost and expense of the
          Neutral Investment Banker.

               (C) If (x) the Mergers are consummated, and (y) the Obligation is
          not paid in full prior to or simultaneously with the Parent Merger,
          the Roberts agree that (i) Lender shall be entitled to retain all or a
          portion of the cash and stock due to the Roberts as part of the Parent
          Merger consideration and apply such consideration towards the payment
          of the Obligation, or (ii) the Roberts shall pledge the stock due to
          them as part of the Parent Merger consideration as security for a loan
          from a third-party in an amount sufficient to repay the Obligation
          and, thereafter, they shall tender to Lender the full amount of the
          Obligation owed to such Lender, including principal, accrued but
          unpaid interest on the Loan and fees.

          (v) Optional Prepayment. Borrower shall have the right, from time to
     time before the Maturity Date or payment of the Loan is otherwise demanded,
     to prepay the Loan in whole upon the payment of all principal, accrued
     interest and fees on the amount prepaid to and including the date of
     payment.

          (vi) General Payment Terms. All payments on the Loan shall be made to
     Lender at its principal office in Lubbock, Texas in federal or other
     immediately available funds, and payments shall be applied first to accrued
     interest and then to principal. If any payment is scheduled to become due
     and payable on a day that is not a business day, that payment shall instead
     become due and payable on the immediately following business day, interest
     shall be payable with respect to the extension, and interest on the
     principal portion of the payment shall be payable at the then applicable
     rate during the extension. Interest on the Loan shall be calculated on the
     basis of a year of 360 days for the actual number of days (including the
     first but excluding the last) elapsed, unless the Maximum Rate shall be in
     effect, in which case on the basis of a year of 365 or 366 days, as the
     case may be.

     4. Conditions Precedent.

     (a) Initial Advance. The obligation of Lender to make its initial Advance
after the date hereof is subject to the condition that Lender has received duly
executed copies of each of the documents listed on SCHEDULE 4, each in form and
substance satisfactory to Lender and its legal counsel (those documents together
with this Agreement, and any modifications thereof, collectively, the "LOAN
DOCUMENTS").

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     (b) All Advances. The obligation of Lender to make any Advance under this
Agreement (including the initial Advance) is subject to the conditions precedent
that, as of the date of the Advance and after giving effect thereto: (i) there
exists no "EVENT OF DEFAULT" (defined below) hereunder or under any other Loan
Document, or event which, with the giving of notice or passage of time or both
could become an Event of Default (a "POTENTIAL DEFAULT"); (ii) Lender has
received from Borrower a Notice of Borrowing and all of the statements contained
in the Notice of Borrowing shall be true and correct; and (iii) the
representations and warranties contained in each of the Loan Documents shall be
true in all material respects as though made on the date of the Advance, except
that any representation qualified by "materially," "material," or similar terms
must be true in all respects as though made on the date of the Advance.

     5. Representations and Warranties. To induce Lender to make the Loan
hereunder, Borrower represents and warrants to Lender that:

     (a) The Loan Documents are the legal and binding obligations of Borrower,
enforceable in accordance with their respective terms, except as limited by
bankruptcy, insolvency or other laws of general application relating to the
enforcement of creditors' rights; Borrower has full power and authority to
execute and deliver the Loan Documents and to incur and perform the obligations
provided for therein;

     (b) Neither the execution and delivery of this Agreement and the other Loan
Documents, nor consummation of any of the transactions herein or therein
contemplated, nor compliance with the terms and provisions hereof or thereof,
will contravene or conflict with any provision of law, statute, or regulation to
which Borrower is subject or any judgment, license, order or permit applicable
to Borrower or any indenture, mortgage, deed of trust, or other instrument to
which Borrower or the Roberts may be subject or to which Borrower or either
Roberts may be a party; no consent, approval, authorization or order of any
court, governmental authority or third party is required in connection with the
execution and delivery by Borrower of this Agreement or any of the other Loan
Documents or to consummate the transactions contemplated herein or therein (and
such consents are set forth on SCHEDULE 5(b));

     (c) All financial statements delivered by Borrower to Lender before the
date hereof (i) are true and correct, (ii) fairly present the financial
condition of Borrower, and (iii) have been prepared in accordance with generally
accepted accounting principles, consistently applied, except that interim
financial statements are subject to year-end adjustments, the absence of
footnotes, and other exceptions as may be stated therein; as of the date hereof,
there are no obligations, liabilities, or indebtedness (including contingent and
indirect liabilities) of Borrower not reflected in the financial statements,
except those incurred in the ordinary course of business consistent with past
practice since the date of the most recent financial statements delivered to
Lender; and no material adverse changes have occurred in the financial condition
or business of Borrower since the date of the most recent financial statements
which Borrower has delivered to Lender;

     (d) No litigation, investigation, or governmental proceeding is pending,
or, to the knowledge of any of Borrower's officers, threatened against or
affecting Borrower, which may result in any material adverse change in
Borrower's business, properties, or operations;

     (e) There is no fact known to Borrower that Borrower has not disclosed to
Lender in writing which may result in any material adverse change in Borrower's
business, properties, or operations;

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     (f) Borrower owns all of the assets reflected on its most recent balance
sheet free and clear of all liens, security interests, or other encumbrances,
except as previously disclosed in writing to Lender;

     (g) The principal office, chief executive office, and principal place of
business of Borrower is in St. Louis, Missouri;

     (h) All taxes required to be paid by Borrower have in fact been paid,
except for taxes being contested in good faith by appropriate proceedings for
which adequate reserves have been established;

         (i) Borrower is not in violation of any law, ordinance, governmental
rule, or regulation to which it is subject, and is not in default in any
material respect under any agreement, contract, or understanding to which it is
a party;

     (j) No certificate or statement herewith or heretofore delivered by
Borrower to Lender in connection herewith, or in connection with any transaction
contemplated hereby, contains any untrue statement of a material fact or fails
to state any material fact necessary to keep the statements contained therein
from being misleading;

     (k) The Roberts are the sole owners of all ownership interests in Borrower;

     (l) Each Notice of Borrowing shall constitute, without the necessity of
specifically containing a written statement, a representation and warranty by
Borrower that no Potential Default or Event of Default exists, and that all
representations and warranties contained in each of the Loan Documents are true
and correct in all material respects as though made on the date of the Advance
(except that any representation qualified by "materially," "material," or
similar terms must be true in all respects as though made on the date of the
Advance), except to the extent any such representations and warranties are
expressly stated to be made as of another date; and

     (m) All representations and warranties by Borrower herein shall survive
delivery of the Note and the making of the Loan, and any investigation at any
time made by or on behalf of Lender shall not diminish Lender's right to rely
thereon.

     6. Affirmative Covenants. Until payment in full of the Obligation and all
other obligations and liabilities of Borrower under the Loan Documents, Borrower
agrees and covenants that (unless Lender otherwise consents in writing):

     (a) Borrower shall use all proceeds of the Loan solely for the purposes
described in the second paragraph of this Agreement;

     (b) Borrower shall conduct its business in an orderly and efficient manner
consistent with good business practices and in accordance with all valid
regulations, laws, and orders of any governmental authority and will act in
accordance with customary industry standards in maintaining and operating its
assets, properties, and investments;

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     (c) Borrower shall maintain complete and accurate books and records of its
transactions in accordance with generally accepted accounting principles (at
Lender's option, such records may also be required to be maintained by Lender),
and will give Lender access during business hours to all books, records, and
documents of Borrower and permit Lender to make and take away copies thereof;

     (d) Borrower shall furnish to Lender as soon as available and in any event
within forty-five days after the end of each quarterly fiscal period (except the
last) of each fiscal year of Borrower, copies of the balance sheet of Borrower
as of the end of the fiscal period, and statements of income and retained
earnings and changes in financial position of Borrower for that quarterly fiscal
period and for the portion of the fiscal year ending with such period, in each
case setting forth in comparative form the figures for the corresponding period
of the preceding fiscal year, all in reasonable detail, and certified by the
Roberts as being true and correct and as having been prepared in accordance with
generally accepted accounting principles, consistently applied, subject to
year-end adjustments, the absence of footnotes, and exceptions stated therein;

     (e) Borrower shall furnish to Lender as soon as available and in any event
within ninety days after the close of each fiscal year of Borrower, copies of
the balance sheet of Borrower as of the close of such fiscal year, and
statements of income and retained earnings and changes in financial position of
Borrower for such fiscal year, in each case setting forth in comparative form
the figures for the preceding fiscal year, all in reasonable detail and
accompanied by an opinion thereon (which shall not be qualified by reason of any
limitation imposed by Borrower) of Melman, Alton & Co. or of other independent
public accountants of recognized national standing selected by Borrower and
satisfactory to Lender, to the effect that such financial statements have been
prepared in accordance with generally accepted accounting principles
consistently applied and that the examination of such accounts in connection
with such financial statements has been made in accordance with generally
accepted auditing standards;

     (f) Borrower shall furnish to Lender, immediately upon becoming aware of
the existence of any condition or event constituting an Event of Default or
Potential Default, written notice specifying the nature and period of existence
thereof and any action which Borrower is taking or proposes to take with respect
thereto;

     (g) Borrower shall promptly notify Lender of (i) any material adverse
change in its financial condition or business; (ii) any default under any
material agreement, contract or other instrument to which Borrower is a party or
by which any of its properties are bound, or any acceleration of any maturity of
any indebtedness owing by Borrower, (iii) any material adverse claim against or
affecting Borrower or any of its properties; (iv) any Event of Default, any
Potential Default, or any default under any other Loan Document; and (v) any
litigation, or any claim or controversy which might become the subject of
litigation, against Borrower or affecting any of Borrower's property, if such
litigation or potential litigation might, in the event of an unfavorable
outcome, have a material adverse effect on Borrower's financial condition or
business or might cause an Event of Default;

     (h) Borrower shall promptly furnish to Lender, at Lender's request, such
additional financial or other information concerning assets, liabilities,
operations, and transactions of Borrower as Lender may from time to time
reasonably request;

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     (i) Borrower shall promptly pay all lawful claims, whether for labor,
materials or otherwise, which might or could, if unpaid, become a lien or charge
on any property or assets of Borrower, unless and to the extent only that the
same are being contested in good faith by appropriate proceedings and reserves
deemed adequate by Lender have been established therefor;

     (j) Borrower shall maintain on its properties insurance of responsible and
reputable companies in such amounts and covering such risks as is acceptable to
Lender, is prudent and is usually carried by companies engaged in similar
businesses; Borrower shall furnish Lender, on request, with certified copies of
insurance policies or other appropriate evidence of compliance with the
foregoing covenant;

     (k) Borrower shall preserve and maintain all licenses, privileges,
franchises, certificates, and the like necessary for the operation of its
business;

     (l) Borrower shall cause all unpaid invoices related to the construction of
wireless telecommunications towers which are directed to RWC to be re-invoiced
to the Borrower;

     (m) Borrower shall hold and have at all times all licenses, franchises,
permits and authorizations necessary for the lawful conduct of its business;
shall remain in compliance with all environmental laws; shall hold all required
environmental permits and be in compliance with all conditions of the
environmental permits; and shall obtain all necessary landlord and owner
consents on at least 80% of all wireless telecommunications tower sites;

     (n) To the extent possible, Borrower shall (i) cause the transfer of all
wireless telecommunications tower assets from RWC to the Borrower as
contemplated by Section 4.16 of the Merger Agreement, (ii) take the necessary
steps to perfect its title on such transferred assets, (iii) grant a right of
access to all such wireless telecommunications tower assets to Lender and (iv)
assign all landlord consents and waivers related to tower sites to Lender;

     (o) Borrower shall cause all funds hereafter paid by RWC for tower rent or
other real estate to be applied directly towards the payment of the Obligation;

     (p) Borrower shall provide Lender with all information and documentation
requested by Lender with respect to all accounting functions with respect to the
Borrower's business; and

     (q) If the Mergers are not consummated and the Obligation is not paid in
full, the Borrower shall or shall cause, within ninety (90) days after the date
of a written notice delivered by Lender to RWC advising RWC that the Merger
Agreement is being terminated and that the Mergers will not be consummated,
give, grant and assign to the Lender a perfected, first-priority lien and
security interest in and against all of the Borrower's right, title and interest
in and to all of the Borrower's assets and ownership interests, including but
not limited to, all personal, real and mixed property of the Borrower and its
subsidiaries, and 100% of the ownership interests in Borrower, in each case to
secure the Obligation (the "COLLATERAL"). In connection with the grant and
assignment of such perfected, first-priority lien and security interest, in the
Collateral, Borrower shall, and shall cause each person or entity requested by
Lender, to take such actions as may be

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necessary or desirable to effect the foregoing, including, without limitation,
(1) executing and delivering, or causing such person or entity to execute and
deliver to Lender such security agreements, pledge agreements, mortgages and
other documents, and (2) delivering, or causing such person or entity to deliver
to Lender, such certificates, evidences of corporate action, legal opinions or
other documents as Lender may request, all in form and substance satisfactory to
Lender.

     7. Negative Covenants. Until payment in full of the Note and all other
obligations and liabilities of Borrower hereunder, Borrower covenants that it
shall not (unless Lender otherwise consents in writing):

     (a) incur or assume any indebtedness or borrow money, except for (i) the
Loan; and (ii) trade debt incurred in the ordinary course of business; or sell
any of its accounts receivable, with or without recourse;

     (b) endorse, guarantee, or otherwise become liable for the obligations of
any person, firm, or corporation, except for endorsements of negotiable
instruments by Borrower in the ordinary course of business;

     (c) mortgage, assign, encumber, hypothecate or grant a security interest in
any of Borrower's assets, (provided, however, that the foregoing shall not apply
to inchoate liens for taxes which are not delinquent or which are being
contested in good faith and liens resulting from deposits to secure the payments
of workmen's compensation or social security or to secure the performance of
bids or contracts in the ordinary course of business);

     (d) liquidate, dissolve, or reorganize; or merge or consolidate with, or
acquire all or substantially all of the assets of, any other company, firm, or
association (except as contemplated by the Merger Agreement); or make any other
substantial change in its capitalization or its business;

     (e) pay any dividends on any of its outstanding stock, or purchase, redeem,
or repurchase any of its stock;

     (f) sell any of its assets used or useful in its business, except in the
ordinary course of business; or sell any of its assets to any other person,
firm, or corporation with the agreement that such assets shall be leased back to
Borrower (except as contemplated by the Merger Agreement);

     (g) own, purchase, or acquire, directly or indirectly, any promissory
notes, stock, or securities of any other person, firm, or corporation, other
than securities guaranteed as to the principal and interest by the United States
government; or make any loans or advances to any other person; or

     (h) accept a "First Right to Negotiate" on future wireless
telecommunications tower sites, pursuant to Section 4.15 of the Merger
Agreement.

     8. Default. An "EVENT OF DEFAULT" shall exist if any one or more of the
following events (collectively, "EVENTS OF DEFAULT") occurs:

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     (a) Borrower fails to pay when due any principal of, or interest on, the
Note or any other fee or payment due hereunder or under any other Loan Document;

     (b) any representation or warranty made in any of the Loan Documents proves
to be untrue or inaccurate in any material respect as of the date on which such
representation or warranty is made;

     (c) default occurs in the performance of any of the covenants or agreements
of Borrower, RWC, Michael V Roberts or Steven C. Roberts contained herein or in
any other Loan Document;

     (d) Borrower, RWC, Michael V. Roberts, or Steven C. Roberts (i) applies for
or consents to the appointment of a receiver, custodian, trustee, intervenor, or
liquidator of itself or himself or of all or a substantial part of its or his
assets, (ii) voluntarily becomes the subject of a bankruptcy, reorganization, or
insolvency proceeding or is insolvent or admits in writing that it or he is
unable to pay its or his debts as they become due, (iii) makes a general
assignment for the benefit of creditors (iv) files a petition or answer seeking
reorganization or an arrangement with creditors or to take advantage of any
bankruptcy or insolvency laws, (v) files an answer admitting the material
allegations of, or consent to, or default in answering, a petition filed against
it or him in any bankruptcy, reorganization, or insolvency proceeding, (vi)
becomes the subject of an order for relief under any bankruptcy, reorganization,
or insolvency proceeding, or (vii) fails to pay any money judgment against it or
him before the expiration of 30 days after such judgment becomes final and no
longer subject to appeal;

     (e) an order, judgment, or decree is entered by any court of competent
jurisdiction or other competent authority approving a petition appointing a
receiver, custodian, trustee, intervenor, or liquidator of Borrower, RWC,
Michael V. Roberts, or Steven C. Roberts or of all or substantially all of its
or his assets, and such order, judgment or decree continues unstayed and in
effect for a period of 30 days; or a complaint or petition is filed against
Borrower, Michael V. Roberts, or Steven C. Roberts seeking or instituting a
bankruptcy, insolvency, reorganization, rehabilitation, or receivership
proceeding of any of them, and such petition or complaint is not dismissed
within 30 days;

     (f) Borrower or RWC defaults in the payment of any material indebtedness of
Borrower or RWC or in the performance of any of Borrower's or RWC's material
obligations and such default continues for more than any applicable period of
grace; or

     (g) Michael V. Roberts shall disavow or contest the validity or
enforceability of the guaranty, dated October 18, 2000 by Michael V. Roberts in
favor of the Lender ("MICHAEL ROBERTS GUARANTY") or any other Loan Document
and/or Steven C. Roberts shall disavow or contest the validity or enforceability
the guaranty, dated October 18, 2000 by Steven C. Roberts in favor of the Lender
("STEVEN ROBERTS GUARANTY" and together with the Michael Roberts Guaranty,
collectively the "GUARANTIES") or any other Loan Document.

     9. Remedies Upon Event of Default. If an Event of Default has occurred, has
continued for at least five business days, and is continuing, then Lender at its
option may (i) declare the principal of, and all interest then accrued on, the
Loan and any other liabilities of Borrower to Lender to be forthwith due and
payable, whereupon the same shall forthwith become due and payable without
notice, presentment, demand,

                                       10

<PAGE>

protest, notice of intention to accelerate, notice of acceleration, or other
notice of any kind, all of which Borrower hereby expressly waives, anything
contained herein, in the Note, or in any other Loan Document to the contrary
notwithstanding, (ii) reduce any claim to judgment, and/or (iii) without notice
of default or demand, pursue and enforce any of Lender's rights and remedies
under the Loan Documents or otherwise provided under or pursuant to any
applicable law or agreement.

     10. Preemptive Right. Notwithstanding RWC's LLC Agreement (as defined in
the Assignment Agreement), upon the assignment of the Membership Interests (as
defined in the Assignment Agreement) to Lender pursuant to SECTION 3(c)(iv), RWC
grants to Lender the preemptive right to purchase up to Lender's Proportionate
Interest (defined below) of any Membership Interests that RWC may, from time to
time, propose to sell to any other person; provided, however, that Lender shall
not have any preemptive right with respect to the distribution by, or exchange
offer of, RWC of its securities to all of its members of any Membership
Interests that is made pro rata, based on the percentage of the outstanding
Membership Interests owned by each Assignor (as defined in the Assignment
Agreement) and Lender. As used in this Agreement, "PROPORTIONATE INTEREST" means
the quotient of the Membership Interests owned by Lender, divided by the total
Membership Interests issued and outstanding.

     If RWC proposes to sell securities in a transaction subject to the
preemptive right granted in this Section, then RWC shall give Lender written
notice (a "PREEMPTIVE RIGHT NOTICE") of RWC's intention, describing the type of
securities to be sold and the price and general terms upon which RWC proposes to
sell such securities. If the price specified in the Preemptive Right Notice is
payable in whole or in part in property (including without limitation the
securities of any other issuer) other than cash, then Lender shall pay cash in
lieu of such property, at the fair market value of such property determined in
good faith by Assignors and Lender.

     Lender shall have 15 days from the date the Preemptive Right Notice is
given to notify RWC whether Lender elects to purchase all or any portion of
Lender's Proportionate Interest of such securities for the identical price and
upon the same general terms specified in the Preemptive Right Notice. Such
notice (the "ELECTION NOTICE") shall be in writing and shall state the quantity
of such securities to be so purchased. If Lender does not timely deliver an
Election Notice, it shall be deemed to have waived its preemptive rights with
respect to such sale, provided that RWC consummates the sale within 180 days
after the expiration of such 15 day period at a price equal to or greater than
the price specified in the Preemptive Right Notice given to Lender by RWC under
this Section.

     11. Miscellaneous.

     (a) Waiver. No failure to exercise, and no delay in exercising, on the part
of Lender, any right hereunder shall operate as a waiver thereof, nor shall any
single or partial exercise thereof preclude any other or further exercise
thereof or the exercise of any other right. The rights of Lender hereunder and
under the other Loan Documents shall be in addition to all other rights provided
by law. No notice or demand given in any case shall constitute a waiver of the
right to take other action in the same, similar or other instances without such
notice or demand.

                                       11

<PAGE>

     (b) Notices. Any notices or other communications required or permitted to
be given by any of the Loan Documents must be given in writing and must be
personally delivered, telecopied (with an original notice delivered by overnight
courier service), or mailed by prepaid certified or registered mail to the party
to whom such notice or communication is directed at the address of such party
set forth on the signature page to this Agreement. Any such notice or other
communication shall be deemed to have been given on the day it is received as
aforesaid. Any party may change its address for purposes of this Agreement by
giving notice of such change to all other parties pursuant to this SECTION
11(b).

     (c) Governing Law. This Agreement and the other Loan Documents are being
executed and delivered, and are intended to be performed in, Lubbock County, in
the State of Texas, and the substantive laws of Texas shall govern the validity,
construction, enforcement, and interpretation of this Agreement and all other
Loan Documents, except to the extent: (i) the federal laws governing national
banks expressly supersede and have contrary application; or (ii) federal laws
governing maximum interest rates shall provide for rates of interest higher than
those permitted under the laws of the State of Texas.

     (d) Invalid Provisions. If any provision of this Agreement is held to be
illegal, invalid, or unenforceable under present or future laws effective during
the term of this Agreement, such provision shall be fully severable and this
Agreement shall be construed and enforced as if such illegal, invalid or
unenforceable provision had never comprised a part of this Agreement, and the
remaining provisions of this Agreement shall remain in full force and effect and
shall not be affected by the illegal, invalid, or unenforceable provision or by
its severance from this Agreement.

     (e) Maximum Interest Rate. Regardless of any provisions contained in this
Agreement, the Note, or in any of other Loan Documents, Lender shall never be
deemed to have contracted for or be entitled to receive, collect, or apply as
interest on the Note, any amount in excess of the maximum rate of interest
permitted to be charged by applicable law, and, if Lender ever receives,
collects, or applies as interest any such excess, such amount which would be
excessive interest shall be deemed to be a partial prepayment of principal and
treated hereunder as such, and, if the principal balance of the Note is paid in
full, any remaining excess shall forthwith be paid to Borrower. In determining
whether or not the interest paid or payable under any specific contingency
exceeds the highest lawful rate, Borrower, and Lender shall, to the maximum
extent permitted under applicable law, (i) characterize any non-principal
payment (other than payments which are expressly designated as interest payments
hereunder) as an expense, fee, or premium, rather than as interest, (ii) exclude
voluntary prepayments and the effect thereof, and (iii) spread the total amount
of interest throughout the entire contemplated term of the Note so that the
interest rate is uniform throughout such term.

     (f) Entirety and Amendments. The Loan Documents embody the entire agreement
between the parties and supersede all prior agreements and understandings, if
any, relating to the subject matter hereof and thereof, and this Agreement and
the other Loan Documents may be amended only by an instrument in writing
executed by the party, or an authorized officer of the party, against whom such
amendment is sought to be enforced.

     (g) Parties Bound. This Agreement shall be binding upon and inure to the
benefit of the parties hereto and their respective successors, assigns and legal
representatives; provided, however, that neither party

                                       12

<PAGE>

may, without the prior written consent of the other party, assign any of its
rights, powers, duties, or obligations hereunder.

     (h) Expenses. Borrower will promptly pay all reasonable costs, fees, and
expenses paid or incurred by Lender incident to this Agreement (including the
fees and expenses of counsel to Lender in connection with the negotiation,
preparation, and execution of this Agreement and any amendments hereto) or
incident to the collection of the Loan.

     (i) Headings. Section headings are for convenience of reference only and
shall in no way affect the interpretation of this Agreement.

     (j) Counterparts. This Agreement may be executed in counterparts.

     THIS WRITTEN LOAN AGREEMENT REPRESENTS THE FINAL AGREEMENT BETWEEN THE
PARTIES REGARDING THE SUBJECT MATTER HEREOF AND MAY NOT BE CONTRADICTED BY
PRIOR, CONTEMPORANEOUS, OR SUBSEQUENT ORAL AGREEMENT OF THE PARTIES.

     THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

     If Borrower agrees to the foregoing, Borrower should execute this Agreement
in the spaces indicated on the signature page below.

                     REMAINDER OF PAGE INTENTIONALLY BLANK.
                          SIGNATURE PAGE(S) TO FOLLOW.

                                       13

<PAGE>

         Signature Page to the Loan Agreement dated as of the date first set
forth above, between Roberts Tower Company, as Borrower, and Alamosa Operations,
Inc. as Lender.

                                      ALAMOSA OPERATIONS, INC.

                                      By: /s/ David E. Sharbutt
                                          ------------------------------
                                          Name:  David E. Sharbutt
                                          Title: Chief Executive Officer

                                      Address:
                                      5225 S. Loop 289
                                      Lubbock, Texas 79424
                                      Attention:  Chief Financial Officer

                                      with a copy to:

                                      Skadden, Arps, Slate, Meagher & Flom LLP
                                      4 Times Square
                                      New York, NY 10036
                                      Attention:  Fred White

AGREED AND ACCEPTED
as of October 18, 2000:

ROBERTS TOWER COMPANY

By: /s/ Michael V. Roberts
    ---------------------------------------
    Name:  Michael V. Roberts
    Title: Chief Executive Officer

Address:
1408 North Kingshighway, Suite 300
St. Louis, Missouri 63113
Attention:  Michael V. Roberts

with a copy to:

Armstrong Teasdale LLP
One Metropolitan Square, Suite 2600
St. Louis, Missouri 63102-2740
Attention:  Joseph S. von Kaenel

                                       14

<PAGE>

AGREED AND ACCEPTED
as of October 18, 2000
as to Section 10 hereof, "Preemptive Rights":

ROBERTS WIRELESS COMMUNICATIONS, L.L.C.

By: Roberts Wireless Holdings, LLC, its Sole Member

    By: /s/ Michael V. Roberts
       -----------------------------------
       Michael V. Roberts, its Member

   By: /s/ Steven C. Roberts
       -----------------------------------
       Steven C. Roberts, its Member

Address:
1408 North Kingshighway, Suite 300
St. Louis, Missouri 63113
Attention:  Michael V. Roberts

with a copy to:

Armstrong Teasdale LLP
One Metropolitan Square, Suite 2600
St. Louis, Missouri 63102-2740
Attention:  Joseph S. von Kaenel

                                       15

<PAGE>

                                    EXHIBIT A

                                  FORM OF NOTE

$15,000,000                                                   OCTOBER 18, 2000

     FOR VALUE RECEIVED, the undersigned, ROBERTS TOWER COMPANY ("BORROWER"),
hereby promises to pay to the order of Alamosa Operations, Inc. ("LENDER"), at
Lender's principal office in Lubbock, Texas, on the Maturity Date the lesser of
(a) $15,000,000 and (b) the aggregate principal disbursed by Lender to Borrower
and outstanding and unpaid on such date (together with accrued and unpaid
interest thereon, fees and all other Obligations, as defined in the Loan
Agreement referred to below).

     This Note has been executed and delivered under, and is subject to the
terms of, the Loan Agreement, dated as of October 18, 2000 (as amended,
modified, supplemented, or restated from time to time, the "LOAN AGREEMENT"),
among Borrower and Lender, and is the "Note" referred to therein. Unless defined
herein, capitalized terms used herein that are defined in the Loan Agreement
have the meaning given to such terms in the Loan Agreement. Reference is made to
the Loan Agreement for provisions affecting this Note regarding applicable
interest rates, principal and interest payment dates, final maturity,
prepayments, acceleration of maturity, exercise of rights, payment of attorneys'
fees, court costs, and other costs of collection, certain waivers by Borrower
and others now or hereafter obligated for payment of any sums due hereunder and
security for the payment hereof. Without limiting the immediately preceding
sentence, reference is made to SECTION 11(e) of the Loan Agreement for usury
savings provisions.

     Borrower authorizes Lender and the holder of this Note to endorse on the
Schedule attached to this Note or any continuation thereof or to record in their
internal records all Advances made to Borrower hereunder and all payments made
on account of the principal thereof, which endorsements or recordings shall be
prima facie evidence as to the outstanding principal amount of this Note;
provided, however, any failure by Lender or the holder of this Note to make any
such endorsement or recording shall not limit or otherwise affect the
obligations of Borrower under the Loan Agreement, this Note, or any other Loan
Document.

     THIS NOTE AND THE OTHER LOAN DOCUMENTS HAVE BEEN ENTERED INTO PURSUANT TO
THE SUBSTANTIVE LAWS OF THE STATE OF TEXAS, AND THE APPLICABLE FEDERAL LAWS OF
THE UNITED STATES OF AMERICA SHALL GOVERN THE VALIDITY, CONSTRUCTION,
ENFORCEMENT, AND INTERPRETATION OF THIS NOTE.

ROBERTS TOWER COMPANY                                Title:
a Missouri corporation

By:
   -----------------------------------
   Name:

                                       16

<PAGE>

               SCHEDULE TO PROMISSORY NOTE DATED OCTOBER 18, 2000,
                IN THE ORIGINAL PRINCIPAL AMOUNT OF $15,000,000,
                        EXECUTED BY ROBERTS TOWER COMPANY
                PAYABLE TO THE ORDER OF ALAMOSA OPERATIONS, INC.:

--------------------------------------------------------------------------------
    DATE       AMOUNT OF ADVANCE        PRINCIPAL PAYMENT      PRINCIPAL BALANCE
--------------------------------------------------------------------------------

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

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

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

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

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                                       17

<PAGE>

                                    EXHIBIT B

                FORM OF AGREEMENT TO ASSIGN MEMBERSHIP INTERESTS

     THIS AGREEMENT TO ASSIGN MEMBERSHIP INTERESTS (this "AGREEMENT") is
executed as of October 18, 2000, jointly and severally by the undersigned (each,
an "ASSIGNOR," and collectively, the "ASSIGNORS"), whose addresses are set forth
on the signature page(s) to this Agreement, for the benefit of Alamosa
Operations, Inc., a Delaware corporation ("LENDER").

                                 R E C I T A L S

     A. Roberts Tower Company and Lender have entered into a Loan Agreement
dated as of October 18, 2000 (as amended, modified, supplemented, or restated
from time to time, the "LOAN AGREEMENT").

     B. This Agreement is integral to the transactions contemplated by the Loan
Agreement, and the execution and delivery hereof is a condition precedent to the
making of advances and other extensions of credit under the Loan Agreement.

     ACCORDINGLY, for good and valuable consideration, the receipt and adequacy
of which are hereby acknowledged, each Assignor, jointly and severally, agrees,
for the benefit of Lender, as follows:

1. DEFINITIONS

     1.1 LOAN AGREEMENT DEFINITIONS. Unless otherwise defined herein, or the
context otherwise requires, terms used in this Agreement, including its preamble
and recitals, have the meanings provided in the Loan Agreement.

     1.2 CERTAIN TERMS. The following terms when used in this Agreement,
including its preamble and recitals, have the following meanings (such
definitions to be equally applicable to the singular and plural forms thereof):

     "COMPANY" means (a) Roberts Wireless Communications, L.L.C., a Missouri
limited liability company, as such limited liability company exists or may
hereinafter be restated, amended, or restructured, and (b) any limited liability
company, partnership, joint venture, or corporation formed as a result of the
restructure, reorganization, or amendment of any of such company.

     "EFFECTIVE DATE" means the Maturity Date if (a) the Mergers are not
consummated, and (b) the Obligation (as defined in the Loan Agreement) has not
been paid in full.

     "LLC AGREEMENT" means (a) the Certificate of Organization of the Company,
dated as of May 6, 1998, (b) the Articles of Organization of the Company, dated
as of May 6, 1999, (c) the Operating Agreement of the Company, dated May 4,
1998, and (d) all as amendments, modifications, supplements, or restatements
thereof.

     "MEMBERSHIP INTERESTS" means all membership interests in the Company,
including, without limitation (a) all of Assignors' right, title, and interest
now or hereafter accruing under the LLC Agreement with respect to any interest
now owned or hereafter acquired or owned by Assignors in the Company, and (b)
all distributions,

                                        1

<PAGE>

proceeds, fees, preferences, payments, or other benefits, which Assignors now
are or may hereafter become entitled to receive with respect to such interests
in the Company and with respect to the repayment of all loans now or hereafter
made by Assignors to the Company, and Assignors' undivided percentage interest
in the assets of the Company. It is understood that all of the Membership
Interests are owned by Roberts Wireless Holdings, LLC, a Missouri limited
liability company, which is owned 50% by Michael V. Roberts and 50% by Steven C.
Roberts.

     "OBLIGATION" means, collectively, (a) the "Obligation" as defined in the
Loan Agreement, (b) all indebtedness, liabilities, and obligations of Assignees
arising under this Agreement, and (c) all indebtedness, liabilities, and
obligations of any other party arising under any Guaranty assuring payment of
the Obligation. The Obligation shall include, without limitation, future, as
well as existing, advances, indebtedness, liabilities, and obligations owned by
Borrower or any Guarantor to Lender arising under the Loan Documents.

2. ASSIGNMENT AND OBLIGATIONS

     2.1 ASSIGNMENT OF MEMBERSHIP INTERESTS. On the Effective Date, Assignors
shall jointly and severally cause Roberts Wireless Holdings, LLC to assign,
transfer, and convey to Lender all or a portion of the Membership Interests so
that Lender shall own, in addition to any other membership interests in RWC that
the Lender may already own or have the right to own under any other agreements
with RWC, the Roberts or others, on a fully diluted basis, 10% of the total
membership interests in the Company, and the Membership Interests shall be free
and clear of all liens and encumbrances, other than the pledge of and lien on
such interests to secure the obligations under the DLJ Loan Agreement.

     2.2 CONSENT. To the extent the LLC Agreement requires the consent or
agreement of any Assignor to the assignment, transfer, conveyance, or
encumbrance of all or any portion of the Membership Interests, such Assignor
hereby irrevocably consents to (a) the assignment, transfer, or conveyance of
the Membership Interests, and (b) the assignment, transfer, or conveyance of any
other interests in the Company by any other member of the Company pursuant to
Lender's exercise of its rights and remedies under the Loan Documents.

3. REPRESENTATIONS AND WARRANTIES

     Each Assignor represents and warrants to Lender that:

     3.1 Assignor Michael V. Roberts is the sole legal and beneficial owner of
good and indefeasible title to a 50% membership interest in Roberts Wireless
Holdings, LLC which is the legal and beneficial owner of good and indefeasible
title to 100% of the membership interests in the Company. Such Membership
Interests are free and clear of any lien, except for the security interests as
set forth on SCHEDULE 3, and Michael V. Roberts has all necessary authority to
cause the sale, transfer, and assignment of the Membership Interests as provided
herein, and such assignment and transfer, and any subsequent realization upon
the Membership Interests pursuant hereto (whether acquired by Lender or a third
party), are not contrary to or in conflict with the LLC Agreement or any other
agreement;

     3.2 Assignor Steven C. Roberts is the sole legal and beneficial owner of
good and indefeasible title to a 50% membership interest in Roberts Wireless
Holdings, LLC which is the legal and beneficial owner of good and indefeasible
title to 100% of the membership interests in the Company. Such Membership
Interests are free and clear of any lien, except for the security interests as
set forth on SCHEDULE 3, and Steven C. Roberts has

                                        2

<PAGE>

all necessary authority to cause the sale, transfer, and assignment of the
Membership Interests as provided herein, and such assignment and transfer, and
any subsequent realization upon the Membership Interests pursuant hereto
(whether acquired by Lender or a third party), are not contrary to or in
conflict with the LLC Agreement or any other agreement;

     3.3 No financing statement or other instrument similar in effect covering
all or any part of the Membership Interests is on file in any recording office,
except as set forth on SCHEDULE 3;

     3.4 This Agreement has been duly executed and delivered by each Assignor
and is the legal and binding obligation of such Assignor enforceable in
accordance with its terms;

     3.5 Lender's ownership of any portion of the Membership Interests will not
obligate Lender to make any capital contribution or similar investment in the
Company;

     3.6 Neither the execution and delivery of this Agreement, nor the
consummation of any of the transactions hereby contemplated, nor compliance with
the terms and provisions of this Agreement, will contravene or materially
conflict with (a) any material provision of law, statute, or regulation to which
any Assignor or the Company is subject, or (b) any judgment, license, order, or
permit applicable to any Assignor or the Company. No consent, approval,
authorization, or order of any governmental authority, member, or third party is
required that has not been received or taken (x) for the grant, assignment,
transfer, and conveyance by Assignors of the Membership Interests, (y) for the
execution, delivery, or performance of this Agreement by Assignors, or (z)
except for such notices as are required by the Loan Agreement, for the exercise
by Lender of its rights and remedies hereunder;

     3.7 Each Assignor's address is set forth on the signature page to this
Agreement; and

     3.8 Each Assignor has fully performed each and every one of his obligations
and duties under the LLC Agreement on or prior to the date due; no Assignor has
received any notice of any default in the performance of his obligations under
the LLC Agreement or of any situation which could give rise to such an event of
default thereunder.

4. ASSIGNOR'S COVENANTS. Each Assignor covenants and agrees that until the
Obligation is paid and performed in full:

     4.1 No Assignor will cause, permit, or consent to (i) any amendment or
modification to the LLC Agreement in effect as of the date of this Agreement, or
(ii) any issuance, transfer, or other change in the ownership of the membership
interests in the Company;

     4.2 Each Assignor will pay and discharge promptly when due all taxes,
assessments, forced contributions, governmental charges, fines, penalties, and
any other lawful claims, of every description, payable by such Assignor with
respect to (or which, if not paid, could result in an encumbrance upon) any of
the Membership Interests, except as otherwise permitted by the terms of the Loan
Agreement. In the event that Assignor should, for any reason, fail to pay and
discharge promptly any taxes, assessments, forced contributions, governmental
charges, fines, or penalties when due (subject to the provisions of the Loan
Agreement), then Lender shall be authorized, but shall not be obligated, to pay
the same, with full subrogation to all rights of any Person by reason of such
payment, and the amounts so paid, together with interest thereon as provided
herein, shall be added to the Obligation;

                                        3

<PAGE>

     4.3 No Assignor will sell, transfer, mortgage, or otherwise encumber any
Membership Interests in any manner without first obtaining the written consent
of Lender, which consent may be withheld in Lender's sole and absolute
discretion. Any written consent to any such sale, mortgage, transfer, or
encumbrance shall not be construed to be a waiver of this provision in respect
of any subsequent proposed sale, mortgage, transfer, or encumbrance;

     4.4 Each Assignor will, at his expense and in such manner and form as
Lender may from time to time reasonably require, execute, deliver, file, and
record any specific assignment or other instruments, financing statements,
certificates, or papers, and take any other action that may be necessary or
desirable, or that Lender may from time to time reasonably request, in order to
preserve, protect, and enforce this Agreement and to enable Lender to exercise
and enforce its rights hereunder with respect to any of the Membership
Interests. In the event, for any reason, that the law of any jurisdiction other
than the State of Texas becomes or is applicable to the Membership Interests, or
any part thereof, each Assignor agrees to execute and deliver all such
instruments and to do all such other things that may be necessary or appropriate
to preserve, protect, and enforce this Agreement under the law of such other
jurisdiction, to at least the same extent that this Agreement would be protected
under the Code;

     4.5 If any Assignor receives, by virtue of being or having been an owner of
any of the Membership Interests, any notes, other instruments, options, cash
distributions, or any other distribution, then such Assignor shall receive the
same in trust for the benefit of Lender, shall immediately notify Lender of such
receipt, and shall immediately take all such actions and execute all such
documents as Lender deems necessary or appropriate;

     4.6 Each Assignor will notify Lender in writing prior to any change of such
Assignor's address;

     4.7 Each Assignor shall cause to be obtained any and all waivers and
consents necessary to make effective the assignment, transfer, and conveyance
contained in SECTION 2.1, including, without limitation, all necessary waivers
and consents from the other members of the Company;

     4.8 Each Assignor shall perform fully all obligations imposed upon it by
any agreements or instruments concerning all or any part of the Membership
Interests, including, without limitation, the LLC Agreement, and shall maintain
in full force and effect all such agreements and instruments, and shall not
amend or modify, or consent to the amendment or modification of such agreements
or instruments, without the prior written consent of Lender; and

     4.9 Each Assignor shall promptly notify Lender of any material adverse
change in any material fact or material circumstance warranted or represented by
such Assignor in this Agreement or any other Loan Document or in any other
writing furnished by such Assignor to Lender in connection with the Membership
Interests or the Obligation, and shall promptly notify Lender of any claim,
action, or proceeding affecting title to the Membership Interests, or any part
thereof, and, at the request of Lender, shall appear and defend, at such
Assignor's expense, any such action or proceeding.

                                        4

<PAGE>

5. AGREEMENT TO ASSIGN RIGHTS OF PARTICIPATION AND REQUIRED SALE.

     After the Effective Date, if Assignors, individually or together
("PROPOSING ASSIGNORS"), negotiate and propose a Sale Transaction (defined
below), then Lender shall have the option upon notice as provided below to the
Proposing Assignors to participate in the Sale Transaction on the same terms as
the Proposing Assignors. If Lender fails to give a notice to participate as
provided below, then Lender shall, upon notice from the Proposing Assignors as
provided below participate in the Sale Transaction on the same terms and
conditions as the Proposing Assignors.

     Any Proposing Assignor shall deliver a notice (the "SALE NOTICE") to Lender
setting forth the terms of the proposed Sale Transaction at least 90 days prior
to the consummation of the proposed Sale Transaction. Lender may participate in
the Sale Transaction by delivering a notice to the Proposing Assignor within 30
days after delivery of the Sale Notice. Lender shall be required to participate
in the sale if the Proposing Assignor gives notice to Lender within 10 days
after the expiration of the 30-day period described in the immediately preceding
sentence.

     As used in this Section, "SALE TRANSACTION" means a sale of Membership
Interests held by Proposing Assignors that represent a majority of all the then
outstanding membership interests in the Company.

6. INSPECTION RIGHTS. Lender, at any time, shall, upon reasonable advance
notice, have the right, together with such accountants and other agents or
representatives as it may from time to time designate, to visit and inspect the
Company's properties, assets, books, records, and documents and to discuss the
Company's affairs, finances, and accounts with Assignor's and the Company's
representatives, officers, or directors, during all business hours as Lender may
designate, and to make and take away copies of the Company's records at
Assignors' expense. Each Assignor shall furnish to Lender any information
reasonably requested by Lender in connection with the Membership Interests. Each
Assignor will maintain complete and accurate books and records regarding the
Membership Interests.

7. MISCELLANEOUS

     7.1 LOAN DOCUMENT. This Agreement is a Loan Document executed pursuant to
the Loan Agreement and shall (unless otherwise expressly indicated herein) be
construed, administered, and applied in accordance with the terms and provisions
thereof.

     7.2 AMENDMENTS. No change, amendment, modification, cancellation, or
discharge of any provision of this Agreement shall be valid unless consented to
in writing by the party or parties against whom enforcement thereof is sought
(subject to the terms of the Loan Agreement).

     7.3 NOTICES. Any notices or other communications required or permitted to
be given by this Agreement or any other documents and instruments referred to
herein must be given in accordance with SECTION 11(B) of the Loan Agreement to
(a) Lender at the address given in the Loan Agreement and (b) Assignors at the
addresses given on the signature page hereof.

     7.4 HEADINGS. The headings of sections herein are inserted only for
convenience and shall in no way define, describe, or limit the scope or intent
of any provision of this Agreement.

                                        5

<PAGE>

     7.5 LIMITATION. Regardless of any provisions contained in this Agreement,
the Loan Agreement, or any note, notes, or other evidences of the Obligation, or
other instruments executed or delivered in connection therewith, Lender shall
not be entitled to receive, collect, or apply, as interest on the Obligation,
any amount in excess of the highest lawful rate and, in the event that Lender
ever receives, collects, or applies, as interest, any such excess, such amount
which would be excessive interest shall be applied to the reduction of the
unpaid principal balance of the Obligation, and if the principal balance of the
Obligation is paid in full, any remaining excess shall be forthwith paid to
Assignor. In determining whether or not the interest paid or payable, under any
specific contingency, exceeds the highest lawful rate, each Assignor and Lender
shall, to the maximum extent permitted under applicable law, (a) characterize
any non-principal payment as an expense, fee, or premium rather than as
interest, (b) exclude voluntary prepayments and the effects thereof, and (c)
"spread" the total amount of interest throughout the entire term of the Loan
Agreement so that the interest rate is uniform throughout the entire term of the
Loan Agreement.

     7.6 ASSIGNMENT OF LENDER'S RIGHTS. Lender shall have the right to assign
all or any portion of its rights under this Agreement to any subsequent holder
or holders of the Obligation.

     7.7 PARTIES IN INTEREST. As and when used herein, the term "Assignor" shall
mean and include each Assignor herein named and such Assignor's respective
successors and permitted assigns, and the term "Lender" shall mean and include
Lender herein named and its successors and assigns, and all covenants and
agreements herein shall be binding upon and inure to the benefit of each
Assignor and Lender and their respective assigns, provided that Assignor shall
have no right to assign his rights hereunder to any other Person.

     7.8 OBLIGATIONS ABSOLUTE. All rights and remedies of Lender hereunder, and
all obligations of Assignor hereunder, shall be absolute and unconditional
irrespective of:

          (a) any lack of validity or enforceability of the Loan Agreement or
     any other Loan Document or any other agreement or instrument relating to
     any of the foregoing;

          (b) any change in the time, manner, or place of payment of, or in any
     other term of, all or any of the Obligation, or any other amendment or
     waiver of or any consent to any departure from the Loan Agreement or any
     other Loan Document; or

          (c) any other circumstance (other than payment in full and
     satisfaction of the Obligation) that might otherwise constitute a defense
     available to, or a discharge of, Assignor.

     7.9 APPLICABLE LAWS. THIS AGREEMENT AND ALL ISSUES AND CLAIMS ARISING IN
CONNECTION WITH OR RELATING TO THE OBLIGATION, INCLUDING BUT WITHOUT LIMITATION,
ALL CONTRACT, TORT, EQUITY, OR OTHER CLAIMS OR COUNTERCLAIMS SHALL BE GOVERNED
AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF TEXAS (WITHOUT
CONSIDERATION OF ITS CONFLICTS OF LAWS RULES) AND THE APPLICABLE LAWS OF THE
UNITED STATES OF AMERICA. If any provision of this Agreement is held to be
invalid or unenforceable, the validity and enforceability of the other
provisions of this Agreement shall remain unaffected.

                                        6

<PAGE>

     7.10 ENTIRETY. THIS AGREEMENT AND THE CREDIT AGREEMENT EMBODY THE FINAL,
ENTIRE AGREEMENT AMONG ASSIGNOR AND LENDER WITH RESPECT TO THE ASSIGNMENT OF THE
ASSIGNED INTERESTS AND THE OTHER MATTERS ADDRESSED HEREIN AND THEREIN, AND
SUPERSEDE ANY AND ALL PRIOR COMMITMENTS, AGREEMENTS, REPRESENTATIONS, AND
UNDERSTANDINGS, WHETHER WRITTEN OR ORAL, RELATING TO THE SUBJECT MATTER HEREOF
AND THEREOF, AND MAY NOT BE CONTRADICTED OR VARIED BY EVIDENCE OF PRIOR,
CONTEMPORANEOUS, OR SUBSEQUENT ORAL AGREEMENTS OR DISCUSSIONS OF THE PARTIES
HERETO. THERE ARE NO ORAL AGREEMENTS AMONG THE PARTIES HERETO.

     7.11 WAIVER OF TRIAL BY JURY. TO THE FULLEST EXTENT PERMITTED BY APPLICABLE
LAW, ASSIGNORS HEREBY IRREVOCABLY AND EXPRESSLY WAIVES ALL RIGHT TO A TRIAL BY
JURY IN ANY ACTION, PROCEEDING, OR COUNTERCLAIM (WHETHER BASED UPON CONTRACT,
TORT, OR OTHERWISE) ARISING OUT OF OR RELATING TO THIS AGREEMENT OR ANY OTHER
LOAN DOCUMENT OR THE TRANSACTIONS CONTEMPLATED HEREBY OR THEREBY, OR THE ACTIONS
OF LENDER IN THE NEGOTIATION, ADMINISTRATION, OR ENFORCEMENT HEREOF OR THEREOF.

                     REMAINDER OF PAGE INTENTIONALLY BLANK.
                          SIGNATURE PAGE(S) TO FOLLOW.

                                        7

<PAGE>

     EXECUTED as of the date first stated in this Agreement to Assign Membership
Interests.

Address:
                                    ASSIGNOR:

c/o  Roberts Wireless Communications, LLC,    ----------------------------------
1408 North Kingshighway, Suite 300            Michael V. Roberts, an individual
St. Louis, Missouri 63113

Address:
                                    ASSIGNOR:

c/o  Roberts Wireless Communications, LLC,    ----------------------------------
1408 North Kingshighway, Suite 300            Steven C. Roberts, an individual
St. Louis, Missouri 63113

                                        8

<PAGE>

           ACKNOWLEDGMENT OF AGREEMENT TO ASSIGN MEMBERSHIP INTERESTS

The Company hereby (a) acknowledges the agreement to assignment, transfer, and
conveyance of the Membership Interests pursuant to this Agreement and (b)
consents to the terms and conditions set forth in this Agreement.

ROBERTS WIRELESS COMMUNICATIONS, L.L.C.
a Missouri limited liability company

By: Roberts Wireless Holdings, LLC, its Sole Member

   By:
      -------------------------------------------
      Michael V. Roberts, its Member

   By:
      -------------------------------------------
      Steven C. Roberts, its Member

                                        9<PAGE>

                                    GUARANTY
                                    --------

     GUARANTY, dated as of October 18, 2000, made by Michael V. Roberts, an
individual with an address at 1408 North Kingshighway, Suite 300, St. Louis, MO
63113 (the "GUARANTOR"), in favor of Alamosa Operations, Inc., a Delaware
corporation (the "LENDER").

                              W I T N E S S E T H :

     WHEREAS, Roberts Tower Company (the "BORROWER") and the Lender are parties
to a LOAN AGREEMENT dated as of October 18, 2000 (as amended from time to time,
the "LOAN AGREEMENT"); and

     WHEREAS, the Guarantor has ownership interests in the Borrower and derives
benefits from the Loan;

     NOW, THEREFORE, in consideration of the premises and the agreements herein,
the Guarantor hereby agrees with the Lender as follows:

     SECTION 1. Definitions. Reference is hereby made to the Loan Agreement for
a statement of the terms thereof. All terms used in this Guaranty which are
defined therein and not otherwise defined herein shall have the same meanings
herein as set forth therein.

     SECTION 2. Guaranty. The Guarantor hereby (a) irrevocably, absolutely and
unconditionally guarantees the prompt payment by the Borrower, as and when due
and payable (whether by scheduled maturity, required prepayment, acceleration,
demand or otherwise), of all amounts now or hereafter owing in respect of the
Note, the Loan Agreement and the other Loan Documents, including, without
limitation, the Loan, whether for principal, interest (including interest
accruing on or after the filing of any petition in bankruptcy or for
reorganization relating to the Borrower whether or not a claim for post-filing
interest is allowed in such proceeding), fees, expenses or otherwise (the
"GUARANTEED OBLIGATIONS"); and (b) agrees to pay any and all expenses (including
reasonable counsel fees and expenses) incurred by the Lender in enforcing its
rights under this Guaranty.

     SECTION 3. Guarantor's Obligations Unconditional.

     (a) The Guarantor hereby guarantees that the Guaranteed Obligations will be
paid strictly in accordance with the terms of the Loan Documents, regardless of
any law, regulation or order now or hereafter in effect in any jurisdiction
affecting any of such terms or the rights of the Lender with respect thereto.
The Guarantor agrees that his guarantee constitutes a guaranty of payment when
due and not of collection and waives any right to require that any resort be
made by the Lender to any other guaranty or any collateral that may secure any
of the Guaranteed Obligations. The obligations of the Guarantor under this
Guaranty are independent of the obligations under the Loan Agreement and the
other Loan Documents, and a separate action or actions may be brought and

<PAGE>

prosecuted against the Guarantor to enforce this Guaranty, irrespective of
whether any action is brought against the Borrower of any other guarantor if any
of the Guaranteed Obligations or whether the Borrower or any such other
guarantor is joined in any such action. The liability of the Guarantor hereunder
shall be absolute and unconditional irrespective of: (i) any lack of validity or
enforceability of any Loan Document or any agreement or instrument relating
thereto; (ii) any change in the time, manner or place of payment of, or in any
other term in respect of, all or any of the Guaranteed Obligations (including,
without limitation, any extension for longer than the original period), or any
other amendment or waiver of or consent to any departure from any provision of
any Loan Document other than this Guaranty (including the creation or existence
of any Guaranteed Obligations in excess of the amount permitted by any lending
formulas or other conditions contained in the Loan Documents or the amount
evidenced by the Loan Documents); (iii) any exchange or release of, or
non-perfection of any lien on or security interest in, any collateral, or any
release or amendment or waiver of or consent to any departure from any other
guaranty, for all or any of the Guaranteed Obligations; (iv) the existence of
any claim, set-off, defense or other right that the Guarantor may have against
any natural person, corporation, limited partnership, general partnership,
limited liability company, limited liability partnership, joint stock company,
joint venture, association, company, trust, bank, trust company, land trust,
business trust or other organizations, whether or not legal entities, and
Governmental Authorities (as hereinafter defined) (collectively, "Person"),
including, without limitation, the Lender, or (v) any other circumstance which
might otherwise constitute a defense available to, or a discharge of, the
Borrower or any other guarantor in respect of the Guaranteed Obligations or the
Guarantor in respect hereof.

     (b) This Guaranty (i) is a continuing guaranty and shall remain in full
force and effect until such date on which all of the Guaranteed Obligations and
all other expenses to be paid by the Guarantor pursuant hereto shall have been
indefeasibly paid in full in cash and (ii) shall continue to be effective or
shall be reinstated, as the case may be, if at any time any payment of any of
the Guaranteed Obligations is rescinded or must otherwise be returned by the
Lender upon the insolvency, bankruptcy or reorganization of the Borrower or
otherwise, all as though such payment had not been made.

     SECTION 4. Waivers. The Guarantor hereby waives, to the extent permitted by
applicable law, (i) promptness and diligence; (ii) notice of acceptance and
notice of the incurrence of any Guaranteed Obligation by the Borrower; (iii)
notice of any actions taken by the Lender under any Loan Document or any other
agreement or instrument relating thereto; (iv) all other notices, demands and
protests, and all other formalities of every kind in connection with the
enforcement of the Guaranteed Obligations or of the obligations of the Guarantor
hereunder, the omission of or delay in which, but for the provisions of this
Section 4, might constitute grounds for relieving the Guarantor of his
obligations hereunder; (v) any right to compel or direct the Lender to seek
payment or recovery of any amounts owed under this Guaranty from any one
particular fund or source; (vi) any requirement that the Lender protect, secure,
perfect or insure any Lien (as hereinafter defined) or any property subject
thereto or exhaust any right or take any action against the Borrower or any
other Person and (vii) any other defense available to the Guarantor.

     SECTION 5. Subrogation. Until the indefeasible payment in full in cash of
all Guaranteed Obligations together with all other expenses to be paid by the
Guarantor and the termination of the Loan Agreement, the Guarantor hereby
irrevocably waives and agrees he will not exercise any and all rights which he
has or may have at any time or from time to time (whether arising directly or
indirectly by operation of law or contract) to assert any claim against the
Borrower on account of any payments made under this Agreement, including,
without limitation, any and all

                                       2
<PAGE>

existing and future rights of subrogation, reimbursement, exoneration,
contribution and/or indemnity. If any amount shall be paid to the Guarantor on
account of such subrogation rights at any time when all of the Guaranteed
Obligations and all such other expenses shall not have been paid in full, such
amount shall be (a) held in trust for the benefit of the Lender, (b) identified
on the books and records of Guarantor as the Lender's property, and (c)
segregated from the other funds of the Guarantor and shall forthwith be paid
over to the Lender to be applied in whole or in part by the Lender against the
Guaranteed Obligations, whether matured or unmatured, and all such other
expenses in accordance with the terms of the Loan Agreement.

     SECTION 6. Representations and Warranties. The Guarantor hereby represents
and warrants as follows:

     (a) The Guarantor has the legal capacity to own his assets, execute,
deliver and perform this Guaranty.

     (b) The execution, delivery and performance by the Guarantor of this
Guaranty (i) does not and will not contravene any applicable law; (ii) does not
and will not violate any contractual restriction binding on or otherwise
affecting the Guarantor or any of his assets or properties; and (iii) does not
and will not result in or require the creation of any (x) lien, mortgage,
pledge, assignment, security interest, charge or encumbrance of any kind
(including any agreement to give any of the foregoing, any conditional sale or
other title retention agreement and any lease in the nature thereof) and any
option, trust or other preferential arrangement having the practical effect of
any of the foregoing and (y) in the case of securities, any purchase option,
call or similar right of a third party with respect to such securities ("LIEN")
upon or with respect to any of the Guarantor's properties.

     (c) No authorization, approval or other action by, and no notice to or
filing with, any federal, state, provincial, municipal, national or other
government, governmental department, commission, board, bureau, court, agency or
instrumentality or political subdivision thereof or any entity or officer
exercising executive, legislative, judicial, regulatory or administrative
functions of or pertaining to any government or any court, in each case whether
associated with a state of the United States, the United States, or a foreign
entity or government ("GOVERNMENTAL AUTHORITY") or other regulatory body is
required in connection with the due execution, delivery and performance by the
Guarantor of this Guaranty.

     (d) This Guaranty is a legal, valid and binding obligation of the
Guarantor, enforceable against the Guarantor in accordance with its terms,
except as may be limited by applicable bankruptcy, insolvency, reorganization,
moratorium or other similar laws and general principles affecting the
enforcement of creditor's rights generally.

     (e) There is no pending or, to the best knowledge of the Guarantor after
due inquiry, threatened action, suit or proceeding against the Guarantor or to
which any of the assets of the Guarantor is subject, before any court or other
Governmental Authority or any arbitrator (i) which challenges the validity or
enforceability of this Guaranty, or (ii) in which there is a reasonable
possibility of an adverse decision which would materially adversely affect the
condition (financial or otherwise) of the Guarantor.

     (f) The Guarantor now has and will continue to have independent means of
obtaining information concerning the affairs and financial condition of the
Borrower, and has no

                                       3
<PAGE>

need of, or right to obtain from the Lender, any credit or other information
concerning the affairs or financial condition of the Borrower that may come
under the control of the Lender.

     (g) All federal, state, local and foreign tax returns, reports and
statements (collectively, the "TAX RETURNS") required to be filed by the
Guarantor have been filed with the appropriate governmental agencies in all
jurisdictions in which such Tax Returns are required to be filed (after giving
effect to any extensions obtained for the filing thereof), all such Tax Returns
are true and correct in all material respects, and all taxes, charges and other
impositions due and payable have been timely paid prior to the date on which any
fine, penalty, interest, late charge or loss may be added thereto for
non-payment thereof.

     (h) No written statement prepared or furnished to the Lender in connection
with the transactions contemplated hereby, by or on behalf of the Guarantor,
when all such statements are taken as a whole, contains any untrue statement of
a material fact or omits to state a material fact necessary to make the
statements contained therein not misleading. All facts known to the Guarantor
which are material to an understanding of the financial condition, business,
properties or prospects of the Guarantor and the Borrower have been disclosed to
the Lender.

     (i) The Guarantor is not in default under or with respect to any
contractual obligation owed by the Guarantor and, to the knowledge of the
Guarantor after due inquiry, no other party is in default under or with respect
to any contractual obligation owed to the Guarantor.

     (j) No Event of Default (as hereinafter defined) or event which, with the
lapse of time and/or notice, would become an Event of Default (such event, a
"DEFAULT") has occurred and is continuing.

     SECTION 7. Covenants. Until the indefeasible payment in full in cash of all
Guaranteed Obligations and all other expenses to be paid by the Guarantor:

     (a) The Guarantor shall furnish to the Lender no later than December 1,
2000 a summary of assets and liabilities of the Guarantor as of June 30, 2000,
in form and substance acceptable to the Lender, together with a schedule of
contingent liabilities, signed by the Guarantor as fairly presenting his
financial condition as of such date.

     (b) The Guarantor shall have a minimum net worth of $ 25 million.

     (c) The Guarantor shall comply in all material respects with all
requirements of law, contractual obligations, commitments, instruments,
licenses, permits and franchises, the noncompliance with could reasonably be
expected to have a material adverse effect on (i) the business, assets,
revenues, results of operations, or financial condition of the Borrower, (ii)
the ability of the Borrower to perform its material obligations under the Loan
Documents or (iv) the validity or enforceability of the Loan Documents, the
Lender's Liens or the Lender's rights and remedies under the Loan Documents
("MATERIAL ADVERSE EFFECT").

     (d) The Guarantor shall pay and discharge, before the same shall become
delinquent, all lawful governmental claims, taxes, assessments, charges and
levies.

     (e) The Guarantor shall furnish to the Lender promptly and in any event
within two business days after the Guarantor becomes (or should have become)
aware of the existence of

                                       4
<PAGE>

(i) any breach or non-performance of, or any default under, any contractual
obligation which is material to the business, prospects operations or financial
condition of the Borrower or the Guarantor, as the case may be, or (ii) any
event, development or other circumstances which has any reasonable likelihood of
causing of resulting in a Material Adverse Effect, written notice in reasonable
detail specifying the nature of the breach, non-performance, default, event,
development or circumstance, including without limitation, the anticipated
effect thereof, which notice shall be promptly confirmed in writing within five
days.

     (f) (A) If the Mergers are not consummated and the Guaranteed Obligations
are not paid in full , the Guarantor shall, within ninety (90) days after the
date of a written notice delivered by Lender to RWC advising RWC that the Merger
Agreement is being terminated and that the Mergers will not be consummated,
assign, transfer and convey to Lender, without recourse, all or a portion of his
membership interests in RWC so that Lender shall own, in addition to any other
membership interests in RWC that the Lender may already own or have the right to
own under any other agreement with RWC, the Guarantor or others, on a fully
diluted basis, 10% of the total memberships interests in RWC, free and clear of
all liens and encumbrances. Such obligation of the Guarantor is evidenced by the
Assignment Agreement in the Form of Exhibition B to the Loan Agreement.

         (B) If (x) the Mergers are consummated, and (y) the Guaranteed
Obligations are not paid in full prior to or simultaneously with the Parent
Merger, the Roberts agree that Lender shall be entitled to retain all or a
portion of the cash and stock due to the Roberts as part of the Parent Merger
consideration and apply such consideration towards the payment of the Guaranteed
Obligations.

     SECTION 8. Events of Default. Each of the following shall constitute an
"EVENT OF DEFAULT":

     (a) The Guarantor shall fail to perform any term, covenant or agreement
   contained herein;

     (b) Any representation or warranty of the Guarantor herein shall prove to
   have been false in any material respect as of the date on which it was made
   or deemed to have been made;

     (c) The Guarantor shall die or become incapacitated;

     (d) The Guarantor shall (i) apply for or consent to the appointment of a
   receiver, custodian, trustee or liquidator; (ii) be generally unable to pay
   his debts as such debts become due; (iii) make a general assignment for the
   benefit of the Guarantor's creditors; (iv) commence a voluntary case under
   the United States Bankruptcy Code (as now or hereafter in effect); (v) file a
   petition seeking to take advantage of any other law of any jurisdiction
   relating to bankruptcy, insolvency, or composition or readjustment of debts;
   (vi) fail to controvert in a timely and appropriate manner, or acquiesce in
   writing to, any petition filed against the Guarantor in an involuntary case
   under the United States Bankruptcy Code; or (vii) take any action for the
   purpose of effecting any of the foregoing;

     (e) A proceeding or case shall be commenced, without the application or
   consent of the Guarantor, in any court of competent jurisdiction, seeking (i)
   the liquidation of his assets,

                                       5
<PAGE>

   or the composition or readjustment of his debts, (ii) the appointment of a
   trustee, receiver, custodian, liquidator or the like of any substantial part
   of his assets, or (iii) similar relief in respect of the Guarantor under any
   law of any jurisdiction relating to bankruptcy, insolvency, or the
   composition or readjustment of debts, and such proceedings or case shall
   continue undismissed, or an order, judgment or decree approving or ordering
   any of the foregoing shall be entered and continue unstayed and in effect for
   a period of sixty (60) days; or an order for relief against the Guarantor
   shall be entered in an involuntary case under any bankruptcy, insolvency,
   composition, readjustment of debt, liquidation of assets or similar law of
   any jurisdiction; or

     (f) The Guarantor shall disavow this Guaranty.

     SECTION 9. Notices, Etc. All notices and other communications provided for
hereunder shall be in writing and shall be mailed, telecopied or delivered, if
to the Guarantor, to the address set forth below his signature to this Guaranty;
if to the Lender, to it at its address set forth in the Loan Agreement; or, as
to any such Person, at such other address as shall be designated by said Person
in a written notice to such other Person complying as to delivery with the terms
of this Section 9. All such notices and other communications shall be effective
(i) if mailed, when received or three business days after mailing, whichever
first occurs, (ii) if telecopied, when transmitted and a confirmation is
received, or (iii) if delivered, upon delivery.

     SECTION 10. Consent to Jurisdiction; Waiver of Immunities.

     (a) The Guarantor hereby irrevocably submits to the jurisdiction of any
Texas State or Federal court sitting in _________ in any action or proceeding
arising out of or relating to this Guaranty, and the Guarantor hereby
irrevocably agrees that all claims in respect of such action or proceeding may
be heard and determined in such Texas State or Federal court. The Guarantor
irrevocably consents to the service of any and all process in any such action or
proceeding by the mailing (by certified or registered mail, postage prepaid and
return receipt requested) or delivering a copy of such process to the Guarantor
at its address specified in Section 9 hereof, in the case of mailing, such
service to become effective thirty (30) days after such mailing. The Guarantor
agrees that a final judgment in any such action or proceeding shall be
conclusive and may be enforced in other jurisdictions by suit on the judgment or
in any other manner provided by law.

     (b) Nothing in this Section 10 shall affect the right of the Lender to
serve legal process in any other manner permitted by law or affect the right of
the Lender to bring any action or proceeding against the Guarantor or its
property in the courts of any other jurisdictions.

     (c) The Guarantor hereby expressly and irrevocably waives, to the fullest
extent permitted by law, any objection which he may now or hereafter have to the
laying of venue of any such action or proceeding brought in any such court
referred to above and any claim that any such action or proceeding has been
brought in an inconvenient forum. To the extent that the Guarantor has or
hereafter may acquire any immunity from jurisdiction of any court or from any
legal process (whether through service or notice, attachment prior to judgment,
attachment in aid of execution or otherwise) with respect to himself or his
property, the Guarantor hereby irrevocably waives such immunity in respect of
his obligations under this Guaranty and the other Loan Documents.

     SECTION 11. WAIVER OF JURY TRIAL. EACH OF THE GUARANTOR AND, BY ACCEPTANCE
HEREOF, THE LENDER WAIVES ANY RIGHT TO A TRIAL BY JURY

                                       6
<PAGE>

IN ANY ACTION, PROCEEDING OR COUNTERCLAIM CONCERNING ANY RIGHTS UNDER THIS
GUARANTY, THE LOAN DOCUMENTS OR UNDER ANY AMENDMENT, WAIVER, CONSENT,
INSTRUMENT, DOCUMENT OR OTHER AGREEMENT DELIVERED OR WHICH IN THE FUTURE MAY BE
DELIVERED IN CONNECTION THEREWITH, OR ARISING FROM ANY RELATIONSHIP EXISTING IN
CONNECTION WITH THIS GUARANTY, AND AGREES THAT ANY SUCH ACTION, PROCEEDING OR
COUNTERCLAIM SHALL BE TRIED BEFORE A COURT AND NOT BEFORE A JURY.

     SECTION 12. Miscellaneous.

     (a) The Guarantor will make each payment hereunder in lawful money of the
United States of America and in immediately available funds to the Lender, at
such address specified by the Lender from time to time by notice to the
Guarantor.

     (b) No amendment of any provision of this Guaranty shall be effective
unless it is in writing and signed by the Guarantor and the Lender, and no
waiver of any provision of this Guaranty, and no consent to any departure by the
Guarantor therefrom, shall be effective unless it is in writing and signed by
the Lender, and then such waiver or consent shall be effective only in the
specific instance and for the specific purpose for which given.

     (c) No failure on the part of the Lender, to exercise, and no delay in
exercising, any right hereunder or under any other Loan Document shall operate
as a waiver thereof, nor shall any single or partial exercise of any right
preclude any other or further exercise thereof or the exercise of any other
right. The rights and remedies of the Lender provided herein and in the other
Loan Documents are cumulative and are in addition to, and not exclusive of, any
rights or remedies provided by law. The rights of the Lender under any Loan
Document against any party thereto are not conditional or contingent on any
attempt by the Lender to exercise any of its rights under any other Loan
Document against such party or against any other Person.

     (d) Any provision of this Guaranty which is prohibited or unenforceable in
any jurisdiction shall, as to such jurisdiction, be ineffective to the extent of
such prohibition or unenforceability without invalidating the remaining portions
hereof or thereof or affecting the validity or enforceability of such provision
in any other jurisdiction.

     (e) This Guaranty shall (i) be binding on the Guarantor and his heirs and
legal representatives, and (ii) inure, together with all rights and remedies of
the Lender hereunder, to the benefit of the Lender and its successors or
transferees in respect of the Note and the other Loan Documents.

     (f) At any time and from time to time, upon the request of the Lender, the
Guarantor shall execute, deliver and acknowledge, or cause to be executed,
delivered and acknowledged, such further documents and instruments and do such
other acts and things as the Lender may reasonably request in order to effect
fully the intent and purposes of this Guaranty and the Loan Documents, and any
other agreements, instruments and documents delivered pursuant hereto or in
connection with the making of the Loan, in proper form for recording and
otherwise in form and substance reasonably satisfactory to the Lender and its
counsel.

                                       7
<PAGE>

     (g) This Guaranty shall be governed by and construed and enforced in
accordance with the internal laws of the State of Texas applicable to contracts
made and to be performed therein without regard to conflict of law principles.

                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]

                                       8
<PAGE>

     IN WITNESS WHEREOF, the Guarantor has caused this Guaranty to be executed
as of the date first above written.

                                         By:/s/ Michael V. Roberts
                                            ------------------------------------
                                            Name: Michael V. Roberts
                                            Address:
                                                     ----------
                                            1408 N. Kingshighway
                                            --------------------
                                            St. Louis, MO 63113
                                            --------------------

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

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