<PAGE>
 
                                                                   EXHIBIT 10.38

                            SHAREHOLDERS' AGREEMENT
                            -----------------------

     THIS SHAREHOLDERS' AGREEMENT ("Agreement") is made and entered into as of
this 12th day of February, 1999, by and among each of the individuals and the
entities listed on Schedule I hereto (individually a "Shareholder" and
collectively the "Shareholders"), Telefonos de Mexico, S.A. de C.V., a
corporation organized under the laws of Mexico ("Telmex"), and Topp Telecom,
Inc., a Florida corporation (the "Corporation").

                            Preliminary Statements
                            ----------------------

     A. The Corporation has (after giving effect to the filing of the Articles
of Amendment) authorized capital of 5,000,000 shares of Voting Common Stock and
5,000,000 shares of Non-Voting Common Stock.

     B. This Agreement is entered into in connection with that certain Purchase
Agreement, dated as of the date hereof (the "Acquisition Agreement"), among the
Corporation, certain of the Shareholders and Inmobiliaria Aztlan, S.A. de C.V.
("Telmex Investor"), a wholly owned subsidiary of Telefonos de Mexico, S.A. de
C.V. ("Telmex"), whereby Telmex Investor has purchased a controlling interest in
the Corporation.

     C. After giving effect to the consummation of the Acquisition Agreement,
the Corporation shall have issued shares of Common Stock to the Shareholders as
set forth on Schedule I.

     D. This Agreement shall amend and replace all Prior Shareholders'
Agreements.

     E. The Corporation and the Shareholders believe that it would be in the
best interest of the Corporation to place certain restrictions upon the right of
transfer of the Shareholder Stock.

     F. The directors of the Corporation, having considered the provisions of
this Agreement, have resolved that in their opinion the restrictions upon the
transfer of the Shareholders' Stock, the provisions for the redemption and/or
purchase of certain of the Shareholders' Stock and the establishment of rights
and obligations upon the occurrence of certain events, all as hereinafter set
forth, are in the best interest of the Corporation and the Shareholders.

                                   Agreement
                                   ---------

     NOW, THEREFORE, in consideration of the premises and mutual covenants set
forth in this Agreement, and such other good and valuable consideration, the
receipt and sufficiency of which is hereby acknowledged, each Shareholder and
the Corporation agree as follows:
<PAGE>
 
                                  ARTICLE ONE

                        Definitions and Interpretation
                        ------------------------------

     1.1  Definitions.  As used herein, the following terms when used in this
          -----------                                                        
Agreement have the meanings set forth below:

     "Acquisition Agreement" shall have the meaning given to it in the
      ---------------------                                           
Preliminary Statements to this Agreement.

     "Affiliate" has the meaning set forth in Rule 12b-2 of the regulations
      ---------                                                            
promulgated under the Securities Exchange Act of 1934, as amended; provided,
that, for purposes of Section 7.1, neither Southwestern Bell nor France Telecom
shall be deemed an Affiliate of the Telmex Investor or Telmex.

     "Agreement" means this Shareholders' Agreement and all exhibits and
      ---------                                                         
schedules hereto.

     "Approved Sale" shall have the meaning given to it in Section 4.1 of this
      -------------                                                           
Agreement.

     "Articles of Amendment" shall mean the Articles of Amendment to Articles of
      ---------------------                                                     
Incorporation of the Corporation filed (or to become effective) on the date
hereof.

     "Block Sale" shall mean a sale by Topp or CellStar after a Qualified Public
      ----------                                                                
Offering of more than 50% of such Shareholder's Stock (representing at least 1%
of the Corporation's then outstanding Common Stock) in a private sale to an
independent third party (excluding sales for estate or tax planning purposes)
not pursuant to Rule 144 under the Securities Act or as a result of the exercise
of registration rights under ARTICLE SIX hereof.

     "Board" means the Board of Directors of the Corporation.
      -----                                                  

     "CellStar Note" shall mean the Amended and Restated Promissory Note, dated
      -------------                                                            
the date hereof, payable to CellStar, Ltd. by the Corporation.

     "CellStar Shareholder" shall mean the shares of Common Stock held by
      --------------------                                               
CellStar Telecom, Inc. or its Affiliate.

     "CellStar Shareholder Stock" shall mean the Shareholder Stock owned by
      --------------------------                                           
CellStar.

     "Class A Common Stock" means the Corporation's Voting Common Stock, par
      --------------------                                                  
value $0.01 per share.

     "Class B Common Stock" means the Corporation's Non-Voting Common Stock, par
      --------------------                                                      
value $0.01 per share.

     "Commission" shall mean the Securities and Exchange Commission.
      ----------                                                    

                                       2
<PAGE>
 
     "Common Stock" means, collectively, the Class A Common Stock and the Class
      ------------                                                             
B Common Stock (or, if the Class A Common Stock and Class B Common Stock are
combined, the combined class of common stock resulting therefrom).

     "Corporation" shall have the meaning given to it in the first sentence of
      -----------                                                             
this Agreement.

     "Demand Registration" shall have the meaning given to it in Section 6.1 of
      -------------------                                                      
this Agreement.

     "Excess Offered Stock" shall have the meaning given to it in Section 3.3(c)
      --------------------                                                      
of this Agreement.

     "Excluded Stock" means (i) the Common Stock issuable pursuant to currently
      --------------                                                           
outstanding options or options granted under the Corporation's Stock Option
Plan, (ii) securities issuable as a stock dividend or upon any subdivision of
shares of Common Stock, as the case may be, provided that the securities issued
pursuant to such stock dividend or subdivision are limited to additional shares
of Common Stock, (iii) securities issuable pursuant to a Qualified Public
Offering, (iv) nonconvertible debt securities, and (v) securities issued in
connection with equipment or debt financing or leases (including securities
issued in consideration of guarantees of such financing or leases).

     "Exit Notice One" shall have the meaning given to it in Section 4.1 of this
      ---------------                                                           
Agreement.

     "Exit Notice Two" shall have the meaning given to it in Section 4.2 of this
      ---------------                                                           
Agreement.

     "Family Group" means the Shareholder and/or the Shareholder's spouse,
      ------------                                                        
parents, brothers, sisters  and descendants (including natural and adopted
children and step children and their spouses) and any trust formed and
maintained solely for the benefit of the Shareholder and/or the such other
Persons.

     "First Refusal Notice Date" shall have the meaning given to it in Section
      -------------------------                                               
3.3(a) of this Agreement.

     "Independent Third Party" shall have the meaning given to it in Section 4.1
      -----------------------                                                   
of this Agreement.

     "Long-Form Registration Demand" shall have the meaning given to it in
      -----------------------------                                       
Section 6.1 of this Agreement.

     "Management Shareholder" shall mean the shareholders listed on Schedule I
      ----------------------                                                  
as Management Shareholders.

     "New Issuance" shall have the meaning given to it in Section 8.1 of this
      ------------                                                           
Agreement.

     "Offered Stock" shall have the meaning given to it in Section 3.3(a)(i) of
      -------------                                                            
this Agreement.

                                       3
<PAGE>
 
     "Offered Terms" shall have the meaning given to it in Section 3.3(a)(ii) of
      -------------                                                             
this Agreement.

     "Offer Price" shall have the meaning given to it in Section 3.3(a)(ii) of
      -----------                                                             
this Agreement.

     "Offerees" shall have the meaning given to it in Section 8.1 of this
      --------                                                           
Agreement.

     "Other Shareholders" shall have the meaning given to it in Section 3.3(c)
      ------------------                                                      
of this Agreement.

     "Permitted Family Group Transferee" means any permitted transferee of a
      ---------------------------------                                     
Management Shareholder that is a member of such Shareholder's Family Group.

     "Person" means an individual, a partnership, a corporation, a limited
      ------                                                              
liability Corporation, an association, a joint stock Corporation, a trust, a
joint venture, an unincorporated organization and a governmental entity or any
department, agency or political subdivision thereof.

     "Prior Shareholders' Agreements" shall mean the following agreements:  (i)
      ------------------------------                                           
Shareholders' Agreement, dated May 15, 1996, among the Corporation, FJ Pollak
and David Topp; (ii) Subscription and Shareholders' Agreement, dated June 17,
1997, between the Corporation and Richard P. Anderson; and (iii) Shareholders'
Agreement, dated as of November 4, 1997, by and among the Corporation, CellStar
Telecom, Inc., David Topp and FJ Pollak, as amended on September 1, 1998.

     "Qualified Public Offering" means the initial public offering of the
      -------------------------                                          
Corporation's Common Stock to the public pursuant to a registration statement
filed and declared effective under the Securities Act.

     "Registration Expenses" shall have the meaning given to it in Section 6.5
      ---------------------                                                   
of this Agreement.

     "Representatives" shall have the meaning given to it in Section 7.2 of this
      ---------------                                                           
Agreement.

     "Securities Act" means the Securities Act of 1933, as amended.
      --------------                                               

     "Selling Shareholder" shall have the meaning given to it in Section 3.3 of
      -------------------                                                      
this Agreement.

     "Shareholder" means the Telmex Investor, the CellStar Shareholder and each
      -----------                                                              
Management Shareholder.

     "Shareholder Stock" shall have the meaning given to it in Section 11.12 of
      -----------------                                                        
this Agreement.

                                       4
<PAGE>
 
     "Short-Form Registration Demand" shall have the meaning given to it in
      ------------------------------                                       
Section 6.1 of this Agreement.

     "Subsidiary" means any corporation with respect to which the Corporation
      ----------                                                             
(or a Subsidiary thereof) owns, directly or indirectly, a majority of the common
stock or has the power to vote or direct the voting of sufficient securities to
elect a majority of the directors.

     "Telmex" shall have the meaning given to it in the first sentence of this
      ------                                                                  
Agreement.

     "Telmex Investor" shall have the meaning given to it in the first sentence
      ---------------                                                          
of this Agreement.

     "Topp" shall mean David Topp and members of his Family Group that own
      ----                                                                
Shareholder Stock as set forth on Schedule I.

     "Topp Family Agreement" shall have the meaning given to it in Section 11.8
      ----------------------                                                   
hereof.

     "Topp Notes" shall mean the Promissory Notes, dated the date hereof,
      ----------                                                         
payable to Topp by the Corporation.

     "Topp Shareholder Stock" shall mean the Shareholder Stock owned by Topp.
      ----------------------                                                 

     1.2  Interpretation.  The words "herein," "hereof," "hereunder" and other
          --------------                                                      
words of similar import refer to this Agreement as a whole, as the same from
time to time may be amended or supplemented and not any particular section,
paragraph, subparagraph or clause contained in this Agreement.  Wherever from
the context it appears appropriate, each term stated in either the singular or
plural shall include the singular and the plural, and pronouns stated in
masculine, feminine or neuter gender shall include the masculine, feminine and
the neuter.

                                  ARTICLE TWO

                           Put Option for Topp Stock
                           -------------------------

     If at any time prior to a Qualified Public Offering the Corporation has
reported positive net earnings for at least two consecutive fiscal quarters and
Topp notifies Telmex of his desire to sell all or a substantial portion of the
Topp Shareholder Stock, Telmex agrees that it will negotiate in good faith
toward the purchase of those shares on reasonable price and other terms to be
agreed by both parties.

                                       5
<PAGE>
 
                                 ARTICLE THREE

                         Restrictions Imposed Upon the
       Transfer of Stock by the Shareholders Other Than Telmex Investor
       ----------------------------------------------------------------

     3.1  General Prohibition on Transfers.  Except as is specifically permitted
          --------------------------------                                      
by the provisions of this ARTICLE THREE, the sale, assignment, pledge, gift,
transfer or other disposition of any Shareholder Stock, either directly or
indirectly, to any person or entity other than the Corporation, the Telmex
Investor, Telmex or any Affiliate of Telmex, is prohibited.

     3.2  Permitted Transfers.  The following transfers of Shareholder Stock
          -------------------                                               
shall be permitted transfers which do not require the giving of a Notice of
Right of First Refusal under Section 3.3 of this ARTICLE THREE.

          (a) Transfers to Family Members.  Notwithstanding the provisions of
              ---------------------------                                    
Section 3.1, each Management Shareholder shall be permitted to transfer (whether
by purchase, assignment, gift, bequest, devise, levy, execution or other means
of transfer) all or any portion of his Shareholder Stock to a Permitted Family
Group Transferee; provided that Permitted Family Group Transferee executes a
written acknowledgment that (i) all Shareholder Stock held by the Permitted
Family Group Transferee will, notwithstanding the transfer to such Permitted
Family Group Transferee, be deemed for all purposes of this Agreement to be
owned by the transferring Shareholder, and (ii) the transferee agrees to be
bound by all of the terms of this Agreement as a Management Shareholder by
written instrument reasonably satisfactory to the Corporation.

          (b) Transfers Among the Management Shareholders.  Notwithstanding the
              -------------------------------------------                      
provisions of Section 3.1, each Management Shareholder shall be permitted to
transfer Shareholder Stock to any other Management Shareholder (as long as such
Management Shareholder is employed by the Corporation) without complying with
the Right of First Refusal provisions of this ARTICLE THREE.

          (c) Transfers by CellStar to Affiliates.  Notwithstanding the
              -----------------------------------                      
provisions of Section 3.1, CellStar shall be permitted to transfer (whether by
purchase, assignment, gift, bequest, devise, levy, execution of other means of
transfer) all or any portion of such Shareholder's Shareholder Stock to an
Affiliate of CellStar; provided that such transferee executes a written
acknowledgment that (i) all Shareholder Stock held by the transferee will,
notwithstanding the transfer to such transferee, be deemed for all purposes of
this Agreement to be owned by the transferring Shareholder, and (ii) such
transferee agrees to be bound by all of the terms of this Agreement by written
instrument reasonably satisfactory to the Corporation.

          (d) Pledge of CellStar Shareholder Stock to Creditors.
              -------------------------------------------------  
Notwithstanding the provisions of Section 3.1, CellStar shall be permitted to
pledge and grant a security interest in all or any portion of the CellStar
Shareholder Stock (i) to any Person who is a party to that certain Credit
Agreement dated as of October 15, 1997 (the "Credit Agreement") among CellStar
Corporation and certain banks; (ii) to any Person who becomes a party to the
Credit Agreement; and (iii) to any Person who extends credit to CellStar in
replacement or amendment of the Credit 

                                       6
<PAGE>
 
Agreement, including without limitation replacements or amendments that extend
additional credit. Any such pledge or grant of a security interest shall be free
of the provisions of this Agreement and any realization of the value of that
pledge or security interest, whether by private sale of the securities that are
the subject matter of the transfer or otherwise, shall be free of this Agreement
and the transferee shall not be bound hereby, except that any such transferee
shall succeed to the rights and obligations of CellStar contained in ARTICLES
FOUR, SIX, SEVEN and EIGHT hereof.

          (e) Transfers Under Other Articles.  Notwithstanding the provisions of
              ------------------------------                                    
Section 3.1, a transfer pursuant to any other provisions of this Agreement shall
be permitted without complying with the Right of First Refusal provisions of
this ARTICLE THREE.

     3.3  Transfers to Third Parties.
          -------------------------- 

          (a) Notice of Right of First Refusal.  Notwithstanding the provisions
              --------------------------------                                 
of Section 3.1, and absent the right to make a transfer of Shareholder Stock
pursuant to Section 3.2, if any Shareholder other than the Telmex Investor (the
"Selling Shareholder") receives a bona fide offer from a party unrelated to the
Selling Shareholder to purchase, assign, transfer or otherwise dispose of
Shareholder Stock owned by such Selling Shareholder, or any interest therein,
and the Selling Shareholder desires to accept such offer, the Selling
Shareholder shall cause such offer to be reduced in writing and the Selling
Shareholder shall, not less than 30 days prior to the date of the proposed sale,
assignment, transfer or other disposition, deliver a Notice of Right of First
Refusal to the Corporation and the Shareholders other than the Selling
Shareholder containing the following information:

               (i)   the number of shares of Shareholder Stock proposed to be so
     transferred (the "Offered Stock");

               (ii)  the terms and conditions of the proposed transfer, 
     including the identity of the proposed transferee(s) and the per share
     price to be charged (if any) for the shares of Shareholder Stock to be
     transferred and the type and nature of the consideration to be received
     therefor (the "Offered Terms"); and

               (iii) an affirmative offer made by the Selling Shareholder to
     transfer the Offered Stock to the Corporation at a price (the "Offer
     Price") equal to the total cash price plus the fair market value of any
     consideration other than cash offered in the proposed transfer for the
     Offered Stock as indicated in the Notice of Right of First Refusal (i.e.,
                                                                         ---- 
     the number of shares multiplied by the per share price, if any, to be
     charged for the shares of Offered Stock to be transferred).

     The date that the Notice of Right of First Refusal is received by the
Corporation shall constitute the First Refusal Notice Date.

          (b) Primary Right of First Refusal by the Telmex Investor.  The Telmex
              -----------------------------------------------------             
Investor shall have the sole and exclusive option to acquire all or any portion
of the shares of 

                                       7
<PAGE>
 
Shareholder Stock offered for transfer in accordance with the provisions of the
Notice of Right of First Refusal for a period of 15 days from the First Refusal
Notice Date. The Telmex Investor may exercise such option by giving written
notice of exercise to the Selling Shareholder prior to the termination of its
exclusive option period. Such notice of exercise shall refer to the Notice of
Right of First Refusal and shall set forth the number of shares to be acquired
by the Corporation.

          (c) Secondary Right of First Refusal by the Corporation.  The
              ---------------------------------------------------      
Corporation shall have the exclusive option from the 16th day to the 30th day
following the First Refusal Notice Date to acquire the Offered Stock not to be
acquired by the Telmex Investor.  The Corporation may exercise such option by
giving written notice of exercise to the Selling Shareholder prior to the
termination of its exclusive option period.  Such notice shall refer to the
Notice of Right of First Refusal and shall set forth the number of shares to be
acquired by the Corporation.

          (d) Tertiary Right of First Refusal by Shareholders.  The Shareholders
              -----------------------------------------------                   
other than the Selling Shareholder and the Telmex Investor (the "Other
Shareholders") shall have an exclusive option from the thirty-first day to the
fiftieth day following the First Refusal Notice Date to acquire the Offered
Stock in accordance with the procedure described in this Section 3.3.  The Other
Shareholders may, by agreement, allocate among themselves the right to acquire
such part of the Offered Stock that will not be acquired by the Corporation.

     In the absence of such an agreement, each Other Shareholder will be
entitled to give written notice to the Selling Shareholder, to the Corporation,
and to the Other Shareholders, within fifty days from the First Refusal Notice
Date, of such Shareholder's election to acquire all or any part of such Offered
Stock that is not being acquired by the Corporation  ("Excess Offered Stock").
If the Shareholders' offers to purchase exceed the amount of Excess Offered
Stock, the option to acquire such Stock shall be allocated among the
Shareholders desiring to purchase it as follows:

               (i)   Each Shareholder shall be absolutely entitled to acquire 
     any number of shares of Excess Offered Stock that is equal to or less than
     his proportionate part of such Excess Offered Stock, based upon the number
     of shares owned by each Shareholder electing to acquire any of the Excess
     Offered Stock;

               (ii)  Each Shareholder electing to acquire more than his
     proportionate part of the Excess Offered Stock under the previous
     allocation step may acquire a proportionate part of the remainder of the
     Excess Offered Stock which is not previously allocated to Other
     Shareholders (i.e., because some acquiring Shareholders did not elect to
                   ----                                                      
     acquire their entire ratable portion under the preceding allocation  step),
     based upon the number of shares owned by each such acquiring Shareholder
     who has elected to acquire more than his proportionate part of the Excess
     Offered Stock;

               (iii) The allocation procedure described in Paragraph (ii) shall
     be repeated until all of the Excess Offered Stock has been allocated among
     all of the Shareholders electing to acquire such Excess Offered Stock and
     no such acquiring 

                                       8
<PAGE>
 
     Shareholder has been allocated more than his proportionate share of the
     remaining Excess Offered Stock under the last such allocation step.

     If a husband and wife are both Shareholders, the Shareholder Stock owned by
each such spouse shall be limited to the Stock actually registered in a spouse's
name plus one-half of the Stock registered in the joint names of both spouses
for the limited purpose of determining each Shareholder's proportionate part of
the Offered Stock.

     If the Corporation and Other Shareholders have not given written notice of
election to acquire all of the Offered Stock within fifty days of the First
Refusal Notice Date, then between the fifty-first and sixtieth day following the
First Refusal Notice Date, the Corporation, the Telmex Investor or any of the
Other Shareholders may give written notice to the Selling Shareholder, to the
Corporation, and to the Other Shareholders of an election to purchase any or all
of the Offered Stock that the Corporation or Other Shareholders have not
previously agreed to purchase.  Such additional shares shall be allocated on a
first-to-give-notice basis determined as of the date written notice is received
by the Corporation.

          (e) Requirement to Purchase All Offered Stock.  Notwithstanding the
              -----------------------------------------                      
provisions of the preceding Sections, the option to purchase shares of
Shareholder Stock described in the Notice of Right of First Refusal may be
exercised and the Closing (as hereinafter defined) consummated only if the
Corporation, the Telmex Investor and the Other Shareholders, if applicable,
collectively agree to purchase all of the shares of the Offered Stock.

          (f) Closing and Tender Requirements.  The closing shall be held at the
              -------------------------------                                   
principal office of the Corporation, at 10:00 a.m. on the sixty-fifth day
subsequent to the date of giving of the Notice of Right of First Refusal.  At
the closing, the Selling Shareholder shall present to the Corporation and/or the
acquiring Shareholders, as the case may be, all share certificates for
Shareholder Stock required to be sold in proper form for transfer.  Such
Shareholder Stock shall be transferred free of all liens and encumbrances or
adverse claims of any kind or character.  At the closing, the Corporation and/or
the acquiring Shareholders, as the case may be, upon receipt of proper tender of
the Shareholder Stock, shall tender full payment of the Offer Price in
conformity with the Offered Terms as set forth in the Notice of Right of First
Refusal, or upon such other terms and conditions as favorable or more favorable
to the Offered Terms.

          (g) Permitted Transfer Following Right of First Refusal.  If all of
              ---------------------------------------------------            
the Shareholder Stock identified in the Notice of Right of First Refusal is not
purchased by the Corporation and/or the acquiring Shareholders prior to the
sixty-sixth day subsequent to the First Refusal Notice Date, then all of such
Shareholder Stock (including any Shareholder Stock for which a proper tender was
made) may be transferred by the Selling Shareholder at any time during the
ensuing thirty days in strict conformity with the Offered Terms set forth in the
Notice of Right of First Refusal; provided, however, the purchaser(s) of such
Shareholder Stock must execute a written acknowledgment that he or they have
become a Shareholder as if he or they had 

                                       9
<PAGE>
 
been original signatory parties to this Agreement and that he or they agree to
be bound by the terms of this Agreement.

     3.4  Notification to Board of Solicited Offers.  In addition to the other
          -----------------------------------------                           
provisions of this ARTICLE THREE, in the event any Shareholder desires to
solicit third parties to purchase such Shareholder's Shareholder Stock, such
Shareholder shall notify the Board in writing at least 30 days prior to making
any such solicitation.  After such notice has been given, the Shareholder shall
then be subject to the right of first refusal provisions contained elsewhere in
this ARTICLE THREE if a bona fide offer is received from any third party.

     3.5  Transfers Include Foreclosure.  For purposes of this ARTICLE THREE, a
          -----------------------------                                        
transfer of Shareholder Stock by a Shareholder shall be deemed to include, but
shall not be limited to, any transfer of legal or beneficial ownership by reason
of foreclosure under any pledge, hypothecation or similar credit transactions,
other than (a) as expressly contemplated by the Acquisition Agreement, or (b)
the pledge by CellStar of its Shareholder Stock pursuant to the provisions of
this Agreement.

     3.6  Compliance Required.  Absent the right to make a transfer of
          -------------------                                         
Shareholder Stock pursuant to Sections 3.2 or 3.3 hereof, any transfer described
in this ARTICLE THREE of a Shareholder's Stock without complying with the giving
of a Notice of Right of First Refusal shall be void, and the Corporation shall
issue a Notice of Right of First Refusal upon discovery of such transfer, a copy
of which shall be sent to the person making such transfer and his transferee.
The duty of the Corporation to cause the issuance of such Notice of Right of
First Refusal shall not be considered to be elective, but shall be mandatory.
Upon the giving of the Notice of Right of First Refusal, the time periods for
the exercise of the options specified in Section 3.3 shall commence running.  If
a Notice of Right of First Refusal had already been given to the Corporation,
but the Corporation is required to issue a new Notice of Right of First Refusal
under this Section 3.6, the prior Notice of Right of First Refusal shall have no
effect and the time periods under the Notice of Right of First Refusal issued by
the Corporation shall apply.

     3.7  Additional Restrictions on Transfer.
          ----------------------------------- 

          (a) Legend. The certificates representing Shareholder Stock will bear
              ------                                                           
the following legend:

          THE SECURITIES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO
          RESTRICTIONS ON TRANSFER, CERTAIN REPURCHASE OPTIONS AND CERTAIN OTHER
          AGREEMENTS SET FORTH IN A SHAREHOLDERS' AGREEMENT AMONG THE COMPANY
          AND ITS SHAREHOLDERS, DATED _______ __, 1999, A COPY OF WHICH MAY BE
          OBTAINED BY THE HOLDER OF THIS CERTIFICATE AT THE COMPANY'S PRINCIPAL
          PLACE OF BUSINESS WITHOUT CHARGE.

                                       10
<PAGE>
 
     (b) Opinion of Counsel.  No holder of Shareholder Stock may sell, pledge or
         ------------------                                                     
otherwise directly or indirectly transfer (whether with or without consideration
and whether voluntarily or involuntarily or by operation of law) any Shareholder
Stock (except pursuant to an effective registration statement under the
Securities Act) without first delivering to the Corporation an opinion of
counsel (reasonably acceptable in form and substance to the Corporation) that
neither registration nor qualification under the Securities Act and applicable
state securities laws is required in connection therewith.

     3.8  Private Sales After a Qualified Public Offering.  In the event Topp or
          -----------------------------------------------                       
CellStar desires to make a Block Sale after a Qualified Public Offering, the
Telmex Investor shall have a right of first refusal to purchase all, but not
less than all, of the shares to be sold in the Block Sale.  The party making
such Block Sale shall notify the Telmex Investor in writing of its intention to
make a Block Sale at least five Business Days prior to the date on which such
Block Sale is priced, and shall include in such notice the price for such
Shares.  The Telmex Investor shall notify the party making such Block Sale of
its intention to exercise its right of first refusal within three Business Days
from the date of receipt of written notice by Topp or CellStar, as the case may
be, and shall tender payment for such Shares within three Business Days of
giving of such notice.  In the event the Telmex Investor does not exercise its
rights hereunder, Topp or CellStar, as the case may be, may proceed with such
Block Sale; provided that, if such sale is consummated within three Business
Days of the date the Telmex Investor was required to provide notification of its
intent to exercise its rights, such sale must be at the same price as identified
in the original notice to the Telmex Investor.

     3.9  Restrictions of Transfer not Applicable to Telmex Investor, Telmex or
          ---------------------------------------------------------------------
Affiliate of Telmex.  Other than the restrictions set forth in Section 3.7, or
-------------------                                                           
as otherwise provided in this Section 3.9, the restrictions on transfer set
forth in this ARTICLE THREE hereof shall not apply to the Telmex Investor,
Telmex or an Affiliate of Telmex; provided, that, (x) the transferee  of any
such Shareholder Stock executes a written acknowledgement that (i) all stock so
transferred shall be deemed to remain Shareholder Stock hereunder and will,
notwithstanding the transfer to such transferee, be deemed for all purposes of
this Agreement to be Shareholder Stock owned by the transferring Shareholder,
and (ii) the transferee agrees to be bound as if the transferee were the Telmex
Investor by all of the terms of this Agreement pursuant to a written instrument
reasonably satisfactory to the Other Shareholders, and (y) in the event the
Telmex Investor exercises its "drag-a-long" rights set forth in Section 4.2
hereof, the Other Shareholders shall have an exclusive option for a period of
ten Business Days from the receipt of the Exit Notice Two to acquire the
Shareholder Stock of the Telmex Investor identified in such notice, such option
to purchase to be allocated among the Other Shareholders as set forth in Section
3.3(d) hereof.  This option to purchase the shares of the Telmex Investor may be
exercised only if the Other Shareholders collectively agree to purchase all of
such shares identified in the Exit Notice Two and, if not so purchased prior to
the 11th Business Day subsequent to the receipt of the Exit Notice Two, the
Other Shareholders will be subject to the drag-a-long rights set forth in
Section 4.2 hereof.

                                       11
<PAGE>
 
                                 ARTICLE FOUR

                   Participation Rights of All Shareholders
                   ----------------------------------------

     4.1  Tag-Along.  If Telmex or the Telmex Investor proposes to sell or
          ---------                                                       
convey, in a single transaction or a series of transactions, all or
substantially all of the shares of Common Stock owned by it, or any interest
therein (other than a transfer of a security interest therein as collateral
security for any obligation of the Telmex Investor), to an independent third
party (including, without limitation, a sale of the Corporation by merger,
consolidation, sale of all or substantially all of its assets, sale of all of
the outstanding Common Stock or otherwise) (an "Approved Sale"), the Telmex
Investor shall give written notice (the "Exit Notice One") to the holders of
Shareholder Stock setting forth the terms and conditions of the proposed
transfer, including the identity of the independent third party, the number of
shares of Common Stock to be transferred, the per share price to be paid for the
shares of Common Stock to be transferred and the type and nature of the
consideration to be received therefor.  If the Telmex Investor shall issue an
Exit Notice One with respect to an Approved Sale, the other holders of
Shareholder Stock, by written notice to the Telmex Investor delivered within 20
days after the date of such Exit Notice One, shall be entitled to require that
the Telmex Investor include in the proposed sale to the independent third party
in the same transaction all of their shares of Common Stock and rights to
acquire shares of Common Stock (or, if the Telmex Investor is selling less than
all of its Common Stock, a percentage of each such holder's shares of Common
Stock and rights to acquire shares of Common Stock equivalent to the percentage
of Common Stock and rights to acquire shares of Common Stock to be sold by the
Telmex Investor), on the same terms and conditions set forth in the Exit Notice
One.  For purposes of this Section 4.1, an "independent third party" is any
person who, prior to such sale, does not own in excess of 5% of the
Corporation's Common Stock on a fully-diluted basis, who is not controlling,
controlled by or under common control with any such 5% owner of the
Corporation's Common Stock and who is not the spouse, ancestor or descendant (by
birth or adoption) of any such 5% owner of the Corporation's Common Stock.

     4.2  Drag-A-Long.  If Telmex or the Telmex Investor proposes to sell or
          -----------                                                       
convey, in a single transaction or a series of transactions, all or
substantially all the shares of Common Stock owned by it, or any interest
therein (other than a transfer of a security interest therein as collateral
security for any obligation of the Telmex Investor), to an independent third
party (including, without limitation, an Approved Sale), the Telmex Investor
shall give written notice (the "Exit Notice Two") to the holders of Shareholder
Stock setting forth the terms and conditions of the proposed transfer, including
the identity of the independent third party, the number of shares of Common
Stock to be transferred, the per share price to be paid for the shares of Common
Stock to be transferred and the type and nature of the consideration to be
received therefor.  By so indicating in the Exit Notice Two, the Telmex Investor
shall be entitled to require the holders of Shareholder Stock to sell to the
independent third party in the same transaction all of their shares of Common
Stock and rights to acquire shares of Common Stock, on the same terms and
conditions set forth in the Exit Notice Two.

                                       12
<PAGE>
 
                                 ARTICLE FIVE

                             Election of Directors
                             ---------------------

     5.1  Voting for Directors.  During the term of this Agreement, each
          --------------------                                          
Shareholder agrees (i) to use its best efforts to cause the Corporation's Board
of Directors to fix the number of their members at seven (7), (ii) to vote all
shares of Shareholder Stock owned by such Shareholder to elect seven (7)
directors of the Corporation; and (iii) that at each meeting of the shareholders
of the Corporation for the election of directors, each Shareholder shall vote
all shares of Shareholder Stock owned by such Shareholder for the election of
the seven (7) persons as provided in Section 5.2.

     5.2  Nominations.  (i) As long as Topp owns at least 8% of the outstanding
          -----------                                                          
shares of Common Stock, Topp shall be entitled to designate one (1) nominee for
election as director, (ii) as long as FJ Pollak is employed by the Corporation
and owns at least 1% of the outstanding shares of Common Stock, FJ Pollak shall
be entitled to designate one (1) nominee for election as director, (iii) as long
as the CellStar Shareholder owns at least 8% of the outstanding shares of Common
Stock, CellStar Shareholder shall be entitled to designate one (1) nominee for
election as director, and (iv) Telmex Investor shall be entitled to designate
the remaining nominees for election as director.  Each Shareholder agrees to
vote such Shareholder's shares of Stock in favor of the election of the nominees
designated above.

     5.3  Vacancies.  During the term of this Agreement, should a vacancy in the
          ---------                                                             
Board of Directors be caused by death, resignation, or removal for any other
reason, each of the Shareholders agrees to vote all shares of Shareholder Stock
owned by such Shareholder, and each Shareholder who is then a director agrees,
insofar as it is consistent with his fiduciary duties as a director, to vote as
director to appoint the persons designated as follows:

               (i)   In the event of a vacancy in the Board caused by the death,
     resignation or removal for any reason of a director nominated by Telmex
     Investor, the nominee for that vacancy shall be designated by Telmex
     Investor.  Such nominee shall hold office until the next meeting of the
     Corporation's shareholders at which directors are elected.

               (ii)  In the event of a vacancy in the Board caused by the death,
     resignation or removal for any reason of a director nominated by David
     Topp, the nominee for that vacancy shall be designated by David Topp.  Such
     nominee shall hold office until the next meeting of the Corporation's
     shareholders at which directors are elected.

               (iii) In the event of a vacancy in the Board caused by the
     death, resignation or removal for any reason of a director nominated by FJ
     Pollak, the nominee for that vacancy shall be designated by FJ Pollak.
     Such nominee shall hold office until the next meeting of the Corporation's
     shareholders at which directors are elected.

                                       13
<PAGE>
 
               (iv) In the event of a vacancy in the Board caused by the death,
     resignation or removal for any reason of a director nominated by CellStar
     Shareholder, the nominee for that vacancy shall be designated by CellStar
     Shareholder.  Such nominee shall hold office until the next meeting of the
     Corporation's shareholders at which directors are elected.

     5.4  Removal of Directors.  If at any time any Shareholder proposes to
          --------------------                                             
remove any director, each Shareholder agrees to vote all of the Shareholder
Stock held by such Shareholder for such removal if removal has been approved by
the Shareholder which designated such director.

     5.5  Written Consent.  Notwithstanding any reference herein to votes cast
          ---------------                                                     
at a meeting of the Corporation's shareholders, nominees for election as
directors may be designated by the Shareholders acting by written consent
without a meeting to the extent permitted by law and by the articles of
incorporation and the bylaws of the Corporation; provided, however, that nothing
in this Subsection 5.5 shall authorize the designation, election or removal of
directors other than in accordance with the requirements set forth in this
Agreement.

     5.6  Indemnification.  The Corporation shall at all times maintain
          ---------------                                              
provisions in its Bylaws and/or Articles of Incorporation indemnifying all
directors against liability and absolving all directors from liability to the
Corporation and its shareholders to the maximum extent permitted under the law
of the State of Florida.  The Corporation shall not amend the indemnification
provisions of the Corporation's Articles of Incorporation or Bylaws to eliminate
or reduce the indemnification provided for all directors and officers and such
provisions as so written shall be deemed to be a contract with each director
regarding his or her indemnification by the Corporation.  The Corporation shall
also enter into separate indemnification agreements with each director and each
Management Shareholder in his capacity of an officer of the Corporation or any
of its Subsidiaries in substantially the form of Exhibit A attached hereto.
                                                 ---------                 

     5.7  Committees.  For so long as Topp, F.J. Pollak, CellStar or Telmex
          ----------                                                       
Investor is entitled to designate a nominee for election as a director pursuant
to Section 5.2, such party shall also be entitled to designate his or its
representative to any committee of the Board.

                                  ARTICLE SIX

                              Registration Rights
                              -------------------

     6.1  Demand Registrations.
          -------------------- 

          (a) Requests for Registration.  At any time at least six months after
              -------------------------                                        
the Corporation has completed a Qualified Public Offering under the Securities
Act, each Management Shareholder, CellStar Shareholder and Telmex Investor (in
each case, as long as such Shareholder could not otherwise dispose of such
Shares under Rule 144(k) of the Securities Act) may request registration under
the Securities Act of the underwritten public offering of all 

                                       14
<PAGE>
 
or part of their Shareholder Stock on Form S-1 or any similar long-form
registration (a "Long-Form Registration Demand"). In addition, at any time after
the Corporation qualifies for use of a Form S-2 or S-3 under the Act, or any
similar short-form registration, each Management Shareholder, CellStar
Shareholder and Telmex Investor (in each case, as long as such Shareholder holds
at least one percent (1%) of the then outstanding Common Stock) may request
registration under the Act of the underwritten public offering of all or part of
their Stock on such short-form registration statement (a "Short-Form
Registration Demand", which together with a Long-Form Registration Demand is
sometimes collectively referred to as a "Demand Registration"). Each request for
a Demand Registration shall specify the approximate number of shares of
Shareholder Stock requested to be registered. Within ten days after receipt of
any such request, the Corporation will give written notice of such requested
registration to all other holders of Shareholder Stock and will include in such
registration all Shareholder Stock with respect to which the Corporation has
received written requests for inclusion therein in accordance with this Section
6.1(a) and Section 6.2, in each case subject to the pro rata reduction
provisions of Section 6.3.

          (b) Number of Demand Registrations.  In no event shall the Corporation
              ------------------------------                                    
be required to effect in the aggregate (i) more than one Long-Form Registration
or one Short-Form Registration pursuant to this Section 6.1 for any one
Shareholder, or (ii) more than one (1) Demand Registration in any one 12-month
period.  A registration will not count as a Demand Registration until it has
become effective and the Shareholder requesting inclusion in the Demand
Registration is able to include at least 75% of the Shareholder Stock requested
to be included in such registration.  The Corporation will pay all Registration
Expenses as provided in Section 6.5 hereof in connection with any registration
initiated as a Demand Registration whether or not it has become effective.

          (c) Selection of Underwriters.  The Corporation will select the
              -------------------------                                  
investment banker(s) and manager(s) to administer the offering.

     6.2  Piggyback Rights.  If at any time the Corporation proposes to file a
          ----------------                                                    
registration statement under the Securities Act for any underwritten sales of
shares of any of the Corporation's equity securities (or any warrants, units,
convertibles, rights or other securities related or linked to any shares of the
Corporation's equity securities), whether for a secondary offering or for a
primary offering of equity securities by the Corporation, including a Qualified
Public Offering, except for any registration statement (i) on Form S-8 or any
successor form to such form, (ii) on Form S-4 or any successor form to such
form, (iii) filed in connection with an exchange offer or an offering of Common
Stock or of securities convertible or exchangeable into Common Stock made solely
to its existing stockholders in connection with a rights offering or solely to
the Corporation's employees, or (iv) a post-effective amendment to any then
effective registration statement.  the Corporation shall give written notice of
such registration no later than 15 days before its filing with the Commission to
each Shareholder.  If any of the Shareholders so request within 10 days, the
Corporation shall include in any registration the Shareholder Stock of such
Shareholder requested to be included in such registration.

                                       15
<PAGE>
 
     6.3  Pro Rata Reduction and Other Limitations.
          ---------------------------------------- 

          (a) Pro Rata Reduction.  The Corporation shall not be obligated to so
              ------------------                                               
include the Shareholder Stock of any Shareholder (including any Shareholder
initiating a Demand Registration pursuant to Section 6.1) to the extent the
underwriter or underwriters of such securities being otherwise registered by the
Corporation shall determine in good faith that the inclusion of such
Shareholder's Stock would jeopardize the successful sale at the desired price of
such other securities proposed to be sold by such underwriter or underwriters,
in which case the Shareholders requesting to participate in such registration
shall be entitled to participate in any such reduced number of shares of
Shareholder Stock (if any) which may be included in such registration along with
any other Shareholders exercising demand or piggyback rights with respect to
such registration on a pro rata basis in proportion to their relative holdings
of shares of Shareholder Stock (including shares of Shareholder Stock issuable
upon exercise of any vested and immediately exercisable options held by such
Shareholder), in the aggregate.

          (b) Other Limitations on Obligations of the Corporation.
              ---------------------------------------------------  
Notwithstanding the provisions of Sections 6.1 and 6.2 hereof, (i) the
Corporation shall not be required to file a Demand Registration if the
Corporation intends in good faith  to conduct a primary offering of its capital
stock within three months of receipt of the notice from the Shareholder
exercising such Shareholder's rights for a Demand Registration; provided, that,
(x) if the Corporation fails to file a registration statement within such three-
month period, then the Corporation shall be obligated to file a Demand
Registration pursuant to Section 6.1 hereof; and (y) if the Corporation files a
registration statement within such three-month period, the Shareholder shall be
entitled to the piggyback registration rights set forth in Section 6.2 hereof;
and (ii) the Corporation may postpone filing of any registration statement
hereunder for a reasonable period of time (not to exceed 90 days) if the
Corporation has been advised by legal counsel that such filing would require a
special audit or if the Corporation determines reasonably and in good faith that
filing would result in a material detriment to the Corporation.

     6.4  Registration Procedures.  Whenever any Shareholder has requested that
          -----------------------                                              
any Shareholder Stock be registered pursuant to this ARTICLE SIX, the
Corporation will use its best efforts to effect the registration and the sale of
such Shareholder Stock in accordance with the intended method of disposition
thereof and pursuant thereto the Corporation will as expeditiously as possible:

               (i) prepare and file with the Commission a registration statement
     with respect to such Shareholder Stock and use its best efforts to cause
     such registration statement to become effective (provided that before
     filing a registration statement or prospectus or any amendments or
     supplements thereto, the Corporation will furnish to the counsel selected
     by each of the holders of Shareholder Stock covered by such registration
     statement copies of all such documents proposed to be filed, which
     documents will be subject to the review of such counsel);

                                       16
<PAGE>
 
               (ii)   prepare and file with the Commission such amendments and
     supplements to such registration statement and the prospectus used in
     connection therewith as may be necessary to keep such registration
     statement effective for a period of not less than 90 days and comply with
     the provisions of the Securities Act with respect to the disposition of all
     securities covered by such registration statement during such period in
     accordance with the intended methods of disposition by the sellers thereof
     set forth in such registration statement;

               (iii)  furnish to each seller of Shareholder Stock such number of
     copies of such registration statement, each amendment and supplement
     thereto, the prospectus included in such registration statement (including
     each preliminary prospectus) and such other documents as such seller may
     reasonably request in order to facilitate the disposition of the
     Shareholder Stock owned by such seller;

               (iv)   notify each seller of such Shareholder Stock, at any time
     when a prospectus relating thereto is required to be delivered under the
     Securities Act, of the happening of any event as a result of which the
     prospectus included in such registration statement contains an untrue
     statement of a material fact or omits any fact necessary to make the
     statements therein not misleading and, at the request of any such seller,
     the Corporation will prepare a supplement or amendment to such prospectus
     so that, as thereafter delivered to the purchasers of such Shareholder
     Stock, such prospectus will not contain an untrue statement of a material
     fact or omit to state any fact necessary to make the statements therein not
     misleading;

               (v)    use its best efforts to cause all such Shareholder Stock 
     to be listed on each securities exchange on which similar securities issued
     by the Corporation are then listed and, if not so listed, to be listed on
     the NASD automated quotation system and, if listed on the NASD automated
     quotation system, use its best efforts to secure designation of all such
     Shareholder Stock covered by such registration statement as a NASDAQ
     "national market system security" within the meaning of Rule 11Aa2-1 of the
     Commission or, failing that, to secure NASDAQ authorization for such Common
     Stock;

               (vi)   provide a transfer agent and registrar for all such
     Shareholder Stock not later than the effective date of such registration
     statement;

               (vii)  enter into such customary agreements (including
     underwriting agreements in customary form) and take all such other actions
     as the holders of a majority of the Shareholder Stock being sold or the
     underwriters, if any, reasonably request in order to expedite or facilitate
     the disposition of such Shareholder Stock (including, without limitation,
     effecting a stock split or a combination of shares);

               (viii) make available for inspection by any seller of
     Shareholder Stock any underwriter participating in any disposition pursuant
     to such registration statement and any attorney, accountant or other agent
     retained by any such seller or underwriter, all financial and other
     records, pertinent corporate documents and properties of the 

                                       17
<PAGE>
 
     Corporation, and cause the Corporation's officers, directors, employees and
     independent accountants to supply all information reasonably requested by
     any such seller, underwriter, attorney, accountant or agent in connection
     with such registration statement;

               (ix) permit any holder of Shareholder Stock which is reasonably
     likely to be deemed to be an underwriter or a controlling person of the
     Corporation, to participate in the preparation of such registration or
     comparable statement and to require the insertion therein of material,
     furnished to the Corporation in writing, which in the reasonable judgment
     of such holder and its counsel should be included; and

               (x)  in the event of the issuance of any stop order suspending 
     the effectiveness of a registration statement, or of any order suspending
     or preventing the use of any related prospectus or suspending the
     qualification of any Shareholder Stock included in such registration
     statement for sale in any jurisdiction, the Corporation will use it
     reasonable best efforts promptly to obtain the withdrawal of such order.

     6.5  Registration Expenses.  All expenses incident to the Corporation's
          ---------------------                                             
performance of or compliance with this ARTICLE SIX, including without limitation
all registration and filing fees, fees and expenses of compliance with
securities or blue sky laws, printing expenses, messenger and delivery expenses,
and fees and disbursements of counsel for the Corporation and all independent
certified public accountants, underwriters (excluding discounts and commissions)
and other persons or entities retained by the Corporation (all such expenses
being herein called "Registration Expenses"), will be borne by the Corporation,
and the Corporation will, in any event, pay its internal expenses (including,
without limitation, all salaries and expenses of its officers and employees
performing legal or accounting duties), the expense of any annual audit or
quarterly review, the expense of any liability insurance and the expenses and
fees for listing the securities to be registered on each securities exchange on
which similar securities issued by the Corporation are then listed or on the
NASD automated quotation system.  The Corporation shall not, however, pay (i)
underwriting discounts or commissions to the extent related to the sale of the
Shareholder's Stock sold in any registration and qualification, or (ii) fees and
expenses of counsel to the Shareholder relating to such registration and
qualification.

     6.6  Indemnification.  The Corporation will indemnify and hold harmless
          ---------------                                                   
each Shareholder and any underwriter (as defined in the Act) for such
Shareholder and each person, if any, who controls the Shareholder or underwriter
within the meaning of the Act against any losses, claims, damages or
liabilities, joint or several, and expenses (including reasonable attorneys'
fees and expenses and reasonable costs of investigation) to which the
Shareholder or underwriter or such controlling person may be subject, under the
Act or otherwise, insofar as any thereof arise out of or are based upon (i) any
untrue statement or alleged untrue statement of a material fact contained in (A)
any registration statement under which such Shareholder's Stock was registered
under the Act pursuant to this ARTICLE SIX, any prospectus or preliminary
prospectus contained therein, or any amendment or supplement thereto or (B) any
other document incident to the registration of the Stock under the Act or the
qualification of the Shareholder Stock under any state securities laws
applicable to the Corporation, (ii) the omission 

                                       18
<PAGE>
 
or alleged omission to state in any item referred to in the preceding clause (i)
a material fact required to be stated therein or necessary to make the
statements therein not misleading or (iii) any violation or alleged violation by
the Corporation of the Securities Act, the Securities Exchange Act of 1934, as
amended, or any other federal or state securities law, rule or regulation
applicable to the Corporation and relating to action or inaction by the
Corporation in connection with any such registration or qualification, except
insofar as such losses, claims, damages, liabilities or expenses arise out of or
are based upon any untrue statement or alleged untrue statement or omission or
alleged omission based upon information furnished to the Corporation in writing
by such Shareholder or by any underwriter expressly for use therein (with
respect to which information such Shareholder or underwriter shall so indemnify
and hold harmless the Corporation and each person, if any, who controls the
Corporation or such underwriter within the meaning of the Act). The Corporation
will enter into an underwriting agreement with the underwriter or underwriters
for any offering registered under the Act pursuant to this ARTICLE SIX hereof
and with the Shareholders selling Stock pursuant to such offering, and such
underwriting agreement shall contain customary provisions with respect to
indemnification and contribution.

                                 ARTICLE SEVEN

                             Protective Covenants
                             --------------------

     7.1  Transactions with Affiliates of Telmex or Telmex Investor; Allocation
          ---------------------------------------------------------------------
of Corporate Overhead.  All transactions by the Corporation with an Affiliate of
---------------------                                                           
Telmex, Telmex Investor or Telmex, whether or not such transactions are deemed
to be at arms' length or at fair market value, including without limitation,
transactions involving the use of services or personnel of Telmex or its
Affiliates, must be approved by a majority of the Board, excluding any members
of the Board designated by Telmex Investor.  In addition, all allocations of
corporate overhead to the Corporation or a Subsidiary by Telmex or its Affiliate
must be approved by a majority of the Board, excluding any members of the Board
designated by Telmex Investor.  All transactions with Southwestern Bell and
France Telecom must be on terms and conditions substantially equivalent to the
terms and conditions under which the Corporation engages in such transactions
with an independent third party.  For the avoidance of doubt, no provision of
this Agreement shall be deemed or construed to limit any legal duty of Telmex,
Telmex Investor and the directors of the Corporation selected by Telmex Investor
pursuant to Article 5 hereof, whether under statutory or common law or
otherwise.

     7.2  Access to Documents.  The Corporation agrees and each of the
          -------------------                                         
Shareholders agree to cause the Corporation (i) to make available for inspection
by the Shareholders and its directors, officers, employees, counsel,
representatives, accountants and auditors (collectively "Representatives"),
during normal business hours, corporate records, books of account, contracts and
all other documents requested by the Shareholders, and (ii) to permit the
Shareholders reasonable access to the properties of the Corporation, upon
reasonable advance notice to the Corporation, in order to make reasonable
inspection of and examination of the business, 

                                       19
<PAGE>
 
operations and affairs of the Corporation. The Corporation agrees and each of
the Shareholders agree to cause the Corporation to cause its Representatives to
be available upon reasonable notice to answer questions of the Shareholder's
Representatives concerning the business, operations and affairs of the
Corporation and to make available all relevant books and records in connection
with such inspection and examination.

     7.3  Corporate Existence.  The Corporation agrees and each of the
          -------------------                                         
Shareholders agree to cause the Corporation to preserve and maintain its
corporate existence.

     7.4  Financial Statements.  The Corporation agrees and each of the
          --------------------                                         
Shareholders agree to cause the Corporation to furnish to each Shareholder:  (i)
within 120 days after the end of each fiscal year of the Corporation, financial
statements as at the close of such year, audited by independent public
accountants selected by the Corporation, and (ii) within 45 days after the end
of each quarter, financial statements as at the end of such period for such
quarter.  In addition, the Corporation will provide monthly financial statements
within a reasonable period after such statements are available.

     7.5  New Shareholders.  As a condition to the issuance by the Corporation
          ----------------                                                    
of any authorized but unissued shares of Common Stock, or any rights or options
to acquire, or securities convertible into, Common Stock, to any person who is
not a Shareholder, the Corporation shall require such Person to execute an
agreement to become lawfully bound by the provisions of ARTICLES THREE, FOUR,
NINE, TEN and ELEVEN.

     7.6  Distributions.  The Corporation agrees that it will not and, each of
          -------------                                                       
the Shareholders agree not to cause the Corporation to, declare or pay any cash
dividends, make any distribution of property to its shareholders based on such
shareholder's ownership in the Corporation or redeem, retire or purchase shares
of Common Stock; provided that, (i) the Corporation may declare and deliver
dividends and distributions payable only in Common Stock of the Corporation,
(ii) such distributions can be made with the consent of Topp and the CellStar
Shareholders, (iii) transactions contemplated by this Agreement hereof shall not
be subject to this prohibition, (iv) this covenant will expire on the earlier to
occur of (x) the two-year anniversary date of this Agreement, and (y) with
respect to Topp, on the date the Topp Notes have been satisfied in full, and
with respect to the CellStar Shareholder, on the date the CellStar Note has been
satisfied in full, and (v) the Corporation may redeem, retire or purchase shares
of its employees other than the Management Shareholders.

                                 ARTICLE EIGHT

                               Preemptive Rights
                               -----------------

     8.1  Participation Rights.  The Corporation shall, at least 20 days prior
          --------------------                                                
to any issuance by the Corporation of any of its securities other than Excluded
Stock to any Person or Persons (other than issuances to Shareholders and other
holders of Shareholder Stock pursuant to this Section 8.1) after the date of
this Agreement, give written notice of such issuance (a "New 

                                       20
<PAGE>
 
Issuance") to each Management Shareholder and the CellStar Shareholder (the
"Offerees"). The Corporation's written notice to the Offerees shall describe the
securities proposed to be issued by the Corporation and specify the number,
price and payment terms. Each Offeree shall have the right, for a period of 20
days from such notice, to purchase, at the same price and on the same terms and
conditions, that number of additional securities of the Corporation as would be
necessary to preserve such holder's percentage interest in the Common Stock of
the Corporation on a fully diluted, as of the time immediately prior to such New
Issuance. Each Offeree may accept the Corporation's offer as to the full number
of securities offered to such Offeree or any lesser number, by written notice
thereof given by such Offeree to the Corporation prior to the expiration of the
aforesaid 20 day period, in which event the Corporation shall promptly sell and
such Offeree shall buy, upon the terms specified, the number of securities
agreed to be purchased by such Offeree. CellStar may, in its sole discretion,
upon an exercise of its rights hereunder, apply all or a portion of the then
accrued interest and the outstanding principal amount of the CellStar Note to
the purchase price of the securities CellStar is otherwise entitled to purchase,
upon issuance of an appropriate credit on such note, to be applied first to
accrued and unpaid interest and then ratably across all remaining amortizations
of principal of the CellStar Note.

     8.2  Corporation's Right to Sell. The Corporation shall be free at any time
          ---------------------------                                           
after the end of the aforesaid 20 day period and prior to 90 days after the date
of its notice of offer to the Offerees, to offer and sell to any Person the
number of such securities not agreed by the Offerees to be purchased by them, at
a price and on payment terms no less favorable to the Corporation than those
specified in such notice of offer to the Offerees.  However, if such sale or
sales are not consummated within such ninety 90 day period, the Corporation
shall not sell such securities as shall not have been purchased within such
period without again complying with this ARTICLE EIGHT.  The obligations of the
Corporation under this ARTICLE EIGHT shall terminate upon the completion of a
Qualified Public Offering. Notwithstanding anything contained in this Agreement
to the contrary, the written notice of an offer to purchase newly issued shares
to which a participation right applies (as provided in Section 8.1 above) need
not be given prior to the purchase by the Person intending to purchase the newly
issued shares, provided such offer is sent within five days thereafter and
remains open for a 20 day period from the receipt thereof, and further provided
that the Corporation has set aside a number of shares sufficient to satisfy the
obligations of the Corporation pursuant to this ARTICLE EIGHT.

                                 ARTICLE NINE

          Conversion of Class B Common Stock to Class A Common Stock
          ----------------------------------------------------------

     9.1  Conversion of Class B Common Stock to Class A Common Stock.  Subject
          ----------------------------------------------------------          
to Section 9.2 hereof, each share of Class B Common Stock shall be convertible,
at any time and from time to time, and without payment of additional
consideration by the holder thereof into one fully paid and nonassessable share
of Class A Common Stock at the option of a holder thereof.  Upon the exercise of
such option by any Shareholder, all Class B Common Stock shall 

                                       21
<PAGE>
 
immediately be converted to Class A Common Stock, without further action by any
holder of Class B Common Stock.

     9.2  HSR Filing.  In connection with any conversion by a Shareholder of
          ----------                                                        
Class B Common Stock to Class A Common Stock, each Shareholder and the
Corporation agrees to file any notifications, reports and approvals required
under the Hart-Scott-Rodino Antitrust Improvements Act of 1976 and the rules and
regulations promulgated thereunder, at its expense, and to comply with all
reasonable requests of any other party for information necessary in connection
with the preparation by such other party of its notification and report form.

                                  ARTICLE TEN

               The Giving of Notices Required by This Agreement
               ------------------------------------------------

     10.1  Addresses.  Any notices, requests, demands and other communications
           ---------                                                          
required or permitted to be given hereunder must be in writing and, except as
otherwise specified in writing, will be deemed to have been duly given when
personally delivered, telexed or facsimile transmitted, or three days after
deposit in the United States mail, by certified mail, postage prepaid, return
receipt requested, as follows.  The addresses of the Corporation and the
Shareholders, which shall be considered to be their last known addresses unless
subsequently changed in accordance with the provisions of this Agreement, are as
follows:

        To the Corporation:               Topp Telecom, Inc.
                                          8390 N.W. 25 Street
                                          Miami, FL  33122
                                          Telecopier:  (305) 640-2070
                                          Attention:  President

        To Telmex Investor or Telmex:     Inmobiliaria Aztlan, S.A. de C.V.
                                          c/o Telefonos de Mexico, S.A. de C.V.
                                          Parque Via 198
                                          Colonia
                                          06599 Mexico, D.F.
                                          Mexico
                                          Telecopier:  011 52 5 625-3852
                                          Attention:  Daniel Hajj

        To CellStar Shareholder:          CellStar Telecom, Inc.
                                          c/o CellStar Corporation
                                          1730 Briercroft Court
                                          Carrollton, TX  75006
                                          Telecopier:  (972) 323-4539
                                          Attention:  General Counsel

                                       22
<PAGE>
 
        To any Management Shareholder:    at the address reflected on the
                                          Corporation's payroll records

Any party may change its address for the purposes of this Agreement by giving
notice of such change of address to the other parties in the manner herein
provided for giving notice.

     10.2  Form of Notice.  Any notice or communication hereunder must be in
           --------------                                                   
writing, and may be personally delivered or given by registered or certified
mail, return receipt requested, and if given by registered or certified mail,
shall be deemed to have been given and received forty-eight hours after deposit
in the United States mail of a registered or certified letter, return receipt
requested, containing such notice, properly addressed, with postage prepaid; and
if given otherwise than by registered or certified mail, it shall be deemed to
have been given when received by the party to whom it is addressed at the time
received.

     10.3  Failure to Notify of Changed Address.  It shall be the responsibility
           ------------------------------------                                 
of each of the parties to this Agreement to notify all other parties of their
respective addresses and any changes thereof, and any objections to the
performance of any act required hereunder based upon a failure to receive a
notice mailed in conformity with the provisions of this Agreement shall be
meritless.

                                ARTICLE ELEVEN

                                 Miscellaneous
                                 -------------

     11.1  Termination.  This Agreement shall terminate upon the earlier to
           -----------                                                     
occur of (i) the dissolution of the Corporation, (ii) the filing of a voluntary
or involuntary petition by or against the Corporation under Chapter 7 or Chapter
11 of the Bankruptcy Code, (iii) appointment of a receiver for the Corporation,
(iv) the ten-year anniversary date of the date of the Agreement Closing, or (v)
except with respect to the registration rights provisions set forth in ARTICLE
SIX and the right of first refusal provisions set forth in Section 3.8, the
consummation of a Qualified Public Offering (it being understood that the
provisions of this Agreement shall not apply to any Shareholder Stock sold
pursuant thereto).  This Agreement shall terminate as to any specific
Shareholder upon the date such Shareholder ceases to own any Shareholder Stock.

     11.2  Modification.  This Agreement may only be amended, terminated or
           ------------                                                    
modified by the written consent of all parties; provided, that, ARTICLE TWO of
this Agreement may be amended by consent of David Topp and Telmex.

     11.3  Successors.  This Agreement shall be binding upon the parties hereto,
           ----------                                                           
their heirs, administrators, successors, executors and assigns, and the parties
hereto do covenant and agree that they themselves and their respective heirs,
executors, successors, administrators and assigns will execute any and all
instruments, releases, assignments and consents that may be reasonably required
of them to more fully execute the provisions of this Agreement.

                                       23
<PAGE>
 
     11.4  Counterparts.  This Agreement may be executed in several
           ------------                                            
counterparts, each of which shall serve as an original for all purposes, but all
copies of which shall constitute but one and the same Agreement.

     11.5  Headings.  All headings set forth in this Agreement are intended for
           --------                                                            
convenience only and shall not control or affect the meaning, construction or
effect of this Agreement or of any of the provisions thereof.

     11.6  Governing Law.  This Agreement shall be governed by and shall be
           -------------                                                   
construed and enforced in accordance with the laws of the State of Florida.

     11.7  Waiver.  The waiver by any party hereto of a breach of any provision
           ------                                                              
of this Agreement shall not operate or be construed as a waiver of any
subsequent breach by any party.

     11.8  Entire Agreement.  This Agreement constitutes the entire Agreement of
           ----------------                                                     
the parties hereto with respect to the transactions contemplated hereby, and it
is hereby agreed that any prior oral or written agreements concerning the sale
or disposition of Shareholder Stock, including, but not limited to, the Prior
Shareholders' Agreement, shall be null and void.  To the extent of any
inconsistency between this Agreement and that certain Agreement dated as of
December 23, 1994, by and among David Topp, Dora Topp, Mark Topp and Risia Topp
Wire (the "Topp Family Agreement"), the Topp Family Agreement shall be construed
so as to be consistent herewith.

     11.9  Severability.  If any provision of this Agreement shall be held to be
           ------------                                                         
illegal or unenforceable, such illegality or unenforceability shall extend to
that provision solely, and the remainder of this Agreement shall be enforced as
if such illegal or unenforceable provision were not incorporated herein.

     11.10 Specific Performance.  The parties acknowledge that remedies at law
           --------------------                                               
may be inadequate to protect the parties against any actual or threatened breach
of this Agreement, and, without prejudice to any other rights and remedies
otherwise available to the parties, the parties agree that they shall be
entitled to the remedy of specific performance and other temporary and permanent
injunctive or equitable relief without proof of actual damages.

     11.11 Business Days.  Whenever the terms of this Agreement call for the
           -------------                                                    
performance of a specific act on a specified date, which date falls on a
Saturday, Sunday or legal holiday, the date for the performance of such act
shall be postponed to the next succeeding regular business day following such
Saturday, Sunday or legal holiday.

     11.12 Stock References.  References to "Shareholder Stock" herein shall
           ----------------                                                 
mean (i) any Shareholder Stock purchased or otherwise acquired by any
Shareholder, (ii) any equity securities issued or issuable directly or
indirectly with respect to the Shareholder Stock referred to in clause (i) above
by way of stock dividend or stock split or in connection with a combination of
shares, recapitalization, merger, consolidation or other reorganization, and
(iii) any other shares of any class or series of capital stock of the
Corporation held by a Shareholder, including all 

                                       24
<PAGE>
 
Shareholder Stock acquired by the Management Shareholder by reason of any option
agreements between the Corporation and each of the Management Shareholder,
pursuant to which the Corporation will grant each Management Shareholder the
option to purchase, subject to the terms and conditions thereof, additional
shares of Shareholder Stock. As to any particular shares constituting Stock,
such shares will cease to be Stock when they have been (x) effectively
registered under the Act and disposed of in accordance with the registration
statement covering them or (y) sold to the public through a broker, dealer or
market maker pursuant to Rule 144 (or any similar provision then in force) under
the Act.

     11.13  Failure to Deliver Stock.  If a Shareholder (or any personal
            ------------------------                                    
representative or other representative of a Shareholder) who has become
obligated to sell Shareholder Stock of the Corporation hereunder shall fail to
deliver such Shareholder Stock on the terms and in accordance with this
Agreement, the Corporation, in addition to all other remedies it may have, may
send to such obligated party by registered mail, return receipt requested, the
purchase price for such Stock on the terms provided for in this Agreement.
Thereupon, the Corporation, upon written notice to such Shareholder, shall
cancel on its books the certificates representing the Stock to be sold; and
thereupon, all of the obligated Shareholder's rights in and to such Shareholder
Stock shall terminate.

     11.14  David Topp as Representative and Attorney-In-Fact.  Each of Dora
            -------------------------------------------------               
Topp, Risia Wine Topp and Mark Topp hereby appoints David as such Shareholder's
custodian and attorney-in-fact to act for such Shareholder in connection with
the sale of the Common Stock and the other provisions contemplated by the terms
hereof, including the execution and delivery of any amendments to this
Agreement, and David Topp hereby accepts such appointment.  It is agreed by each
of such Shareholders that the arrangements made by such Shareholder hereunder
are irrevocable and that the obligations of such Shareholder hereunder shall not
be terminated by any acts of such Shareholder, or by operation of law, whether
by death or incapacity of such Shareholder or any other party to this Agreement
or the occurrence of any other event; and if any such death, incapacity or any
other such event shall occur after the execution of this Agreement and before
the delivery of the sale of the shares of Common Stock, David Topp is
nevertheless authorized and directed to hold and dispose of the Common Stock in
accordance with the terms and conditions of this Agreement as if such death,
incapacity or other event had not occurred, regardless of whether or not David
Topp shall have received notice of such death, incapacity or other event.

     11.15  Attorneys' Fees and Costs.  If either party seeks to enforce its
            -------------------------                                       
rights or remedies hereunder by arbitration, the prevailing party shall be
entitled to reasonable attorneys' fees, expenses, and costs incurred in
connection therewith.

     11.16  VENUE.  THE PARTIES HERETO CONSENT AND AGREE THAT THE STATE OR
            -----                                                         
FEDERAL COURTS LOCATED IN MIAMI-DADE COUNTY, FLORIDA SHALL HAVE EXCLUSIVE
JURISDICTION TO HEAR AND DETERMINE ANY CLAIMS OR DISPUTES BETWEEN THE PARTIES
PERTAINING TO THIS AGREEMENT OR TO ANY MATTER ARISING OUT OF OR RELATING TO THIS
AGREEMENT, PROVIDED, 

                                       25
<PAGE>
 
NOTHING IN THIS AGREEMENT SHALL BE DEEMED OR OPERATE TO PRECLUDE THE PARTIES
HERETO FROM BRINGING SUIT OR TAKING OTHER LEGAL ACTION IN ANY OTHER JURISDICTION
TO ENFORCE A JUDGMENT OR OTHER COURT ORDER IN FAVOR OF SUCH PARTY. THE PARTIES
HERETO HEREBY WAIVE PERSONAL SERVICE OF THE SUMMONS, COMPLAINTS AND OTHER
PROCESS ISSUED IN ANY SUCH ACTION OR SUIT AND AGREES THAT SERVICE OF SUCH
SUMMONS, COMPLAINTS AND OTHER PROCESS MAY BE MADE BY REGISTERED OR CERTIFIED
MAIL ADDRESSED TO SUCH PARTY AND THAT SERVICE SO MADE SHALL BE DEEMED COMPLETED
UPON THE EARLIER OF ACTUAL RECEIPT THEREOF OR THREE (3) DAYS AFTER DEPOSIT IN
THE U.S. MAIL, PROPER POSTAGE PREPAID.

     11.17  WAIVER OF JURY TRIAL.  THE PARTIES HERETO HEREBY KNOWINGLY,
            --------------------                                       
VOLUNTARILY AND INTENTIONALLY WAIVE ALL RIGHT TO TRIAL BY JURY IN ANY ACTION,
SUIT OR PROCEEDING BROUGHT TO RESOLVE ANY DISPUTE WHETHER SOUNDING IN CONTRACT,
TORT, OR OTHERWISE, BETWEEN THE PARTIES HERETO ARISING OUT OF, CONNECTED WITH,
RELATED TO, OR INCIDENTAL TO THIS AGREEMENT OR THE TRANSACTIONS RELATED HERETO
OR ANY COURSE OF CONDUCT, COURSE OF DEALING, STATEMENTS (WHETHER VERBAL OR
WRITTEN) OR ACTIONS OF EITHER PARTY.  THIS PROVISION IS A MATERIAL INDUCEMENT
FOR THE PARTIES HERETO ENTERING INTO THIS AGREEMENT.

                                       26
<PAGE>
 
     IN WITNESS WHEREOF, the parties to this Agreement have hereunto set their
names as of the date first above written.

                              TOPP TELECOM, INC.

                              By: /s/ F. J. POLLAK
                                 ----------------------------------------------
                                 F. J. Pollak
                                 President


                              TELEFONOS de MEXICO, S.A. de C.V.

                              By: /s/ ADOLFO CEREZO
                                 ----------------------------------------------
                                 Adolfo Cerezo


                              INMOBILIARIA AZTLAN, S.A. de C.V.

                              By: /s/ ADOLFO CEREZO
                                 ----------------------------------------------
                                 Adolfo Cerezo


                              CELLSTAR TELECOM, INC.

                              By: /s/ ELAINE FLUD RODRIGUEZ
                                 ----------------------------------------------
                                 Elaine Flud Rodriguez, Vice President


                              /s/ DAVID TOPP 
                              -------------------------------------------------
                              David Topp


                              /s/ DAVID TOPP 
                              -------------------------------------------------
                              David Topp, as attorney-in-fact for Dora Topp


                              /s/ DAVID TOPP 
                              -------------------------------------------------
                              David Topp, as attorney-in-fact for Risia Wine
                              Topp


                              /s/ DAVID TOPP 
                              -------------------------------------------------
                              David Topp, as attorney-in-fact for Mark Topp


                              /s/ F. J. POLLAK 
                              -------------------------------------------------
                              F. J. Pollak

 
                              /s/ RICHARD P. ANDERSON
                              -------------------------------------------------
                              Richard P. Anderson

                                       27
<PAGE>
 
                                   SCHEDULE I

<TABLE>
<CAPTION>
                                     Number of                           Percentage
   Name of Shareholder            Shares of Stock                        Ownership
------------------------       ----------------------       --------------------------------------
                               Voting      Non-voting       Voting       Non-voting       Combined
                               ------      ----------       ------       ----------       --------
<S>                            <C>         <C>              <C>          <C>              <C>
David Topp*                     2,472         16,151        17.80%           5.48%           6.04%

Dora Topp                         -           18,636                         6.33%           6.04%

David Topp and Dora
 Topp, Joint Tenants
 with right of                  
 Survivorship                     -            5,911                         2.01%           1.92%
 
Mark Topp                         -            6,212                         2.11%           2.01%

Risia Topp Wine                   -            6,212                         2.11%           2.01%
                               ------        -------        -----           -----           -----
Topp Family Total               2,472         53,122        17.80%          18.04%          18.03%

F.J. Pollak*                    1,000         19,000         7.20%           6.45%           6.49%

Richard P. Anderson*              -            1,500                         0.51%           0.49%

CellStar Telecom, Inc.          2,708         57,425        19.50%          19.50%          19.50%

Inmobiliaria Aztlan,           
 S.A. de C.V.                   7,708        163,442        55.50%          55.50%          55.50%
                               ======        =======        =====           =====           ===== 

Total                          13,888        294,489          100%            100%            100%
</TABLE>
----------------------
*   Management Shareholders

                                      D-1