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                                                                   Exhibit 10.28

                                                                  3 YEAR VESTING



                       HIGHWAYMASTER COMMUNICATIONS, INC.

                             STOCK OPTION AGREEMENT

         This OPTION AGREEMENT is entered into by and between HighwayMaster
Communications, Inc., a Delaware corporation (the "Company"), and the
undersigned employee of the Company's subsidiary, HighwayMaster Corporation,
(the "Optionee").

         1.      Grant of Option.  The Company hereby grants to the Optionee
effective as of the date set forth in Section 18 hereof (the "Date of Grant"),
the right and option (the "Option") to purchase up to the aggregate number of
shares of common stock, par value $.01 per share, of the Company (the "Common
Stock") set forth in Section 18 hereof, subject to adjustment pursuant to
Section 3 hereof and subject to the Optionee's acceptance and agreement to all
of the terms and conditions and restrictions described in the HighwayMaster
Communications, Inc. (formerly known as HM Holding Corporation) 1994 Stock
Option Plan, as amended (the "Plan"), a copy of which has been provided to the
Optionee, and to the further terms, conditions and restrictions set forth
below.

         2.      Exercise Price.  Subject to adjustment pursuant to Section 3,
the exercise price payable by the Optionee upon exercise of this Option is set
forth in Section 17 hereof.  

         3.      Tax Status.  This Option will be treated as an "incentive
stock option" within the meaning of Section 422 of the Code to the extent that
any portion of this Option meets the requirements of Section 422 of the Code.
To the extent that any portion of this Option does not meet such Code
requirements, this Option shall be deemed a nonqualified stock option.

         4.      Exercise of Option.  Subject to the terms of the Plan and this
Option Agreement, as of the Date of Grant and each of the first, second, and
third anniversaries of the Date of Grant, Optionee may exercise (cumulatively)
rights to acquire one-third of the Common Stock subject to the Option.
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         5.      Expiration of Option.  This Option shall expire and cease to
be exercisable on the sixth anniversary of the Date of Grant or such earlier
date as may be specified in the Plan.

         6.      Termination of Affiliation.

                 (a)      Subject to the following provisions of this Section 6
         and Article VI of the Plan, this Option may not be exercised unless at
         the time of exercise the Optionee is an Employee of the Company or a
         Subsidiary.

                 (b)      If the Optionee's position as an Employee of the
         Company or a Subsidiary shall terminate for any reason other than
         death, and other than Termination by Employer With Notice without
         cause as set forth in Section 6(d) of that certain Employment
         Agreement entered into between Optionee and a Subsidiary of the
         Company as of May 29, 1998 (the "Employment Agreement"), the Optionee
         may exercise this Option, to the same extent it was exercisable on the
         date of such termination, during the 60-day period following the
         effective date of such termination.  In no event may the Optionee
         exercise this Option later than the date on which the Option would
         have expired under Section 5 hereof.

                 (c)      If the Optionee's position as an Employee of the
         Company or a Subsidiary shall terminate by reason of Termination by
         Employer With Notice without cause as set forth in Section 6(d) of the
         Employment Agreement, the options set forth in Section 17 of this
         Agreement shall continue to vest as set forth in Section 4 of this
         Agreement, and Optionee may exercise this Option for the duration of
         the initial term of the Employment Agreement as set forth in Section 8
         of the Employment Agreement, as if the Employee's employment not been
         terminated until the last day of the initial term set forth in Section
         8 of the Employment Agreement.  In no event may the Optionee exercise
         this Option later than the date on which the Option would have expired
         under Section 5 hereof.


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                 (d)      If the Optionee's position as an Employee of the
         Company or a Subsidiary shall terminate by reason of the Optionee's
         death, the executor or administrator of the Optionee's estate or the
         person to whom this Option is transferred by will or the laws of
         descent or distribution may exercise this Option with respect to any
         or all shares covered by this Option within 60 days after the date of
         the Optionee's death.  In no event may the Optionee or her estate
         exercise this Option later than the date on which the Option would
         have expired under Section 5 hereof.

         7.      Procedure to Exercise.  This Option may be exercised only by
delivery of a written notice to the Company at its principal office, stating
the number of shares of Common Stock as to which the Option is being exercised
and accompanied by payment in full in cash or by certified check of the
exercise price for all such shares.

         8.      Nontransferability of Option.  This Option shall not be
assignable or transferable other than by will or the laws of descent and
distribution and shall be exercisable only by the Optionee during his lifetime.

         9.      Continued Employment or Retention.  Subject to the terms of
any employment agreement between the Company and the Optionee, nothing herein
shall confer upon the Optionee any right to be continued in the employ or
retention of the Company or a Subsidiary or shall prevent the Company or
Subsidiary which employs or retains the Optionee from terminating such
employment in accordance with the Employment Agreement.

         10.     Rights as Shareholder.  Nothing herein is intended to or shall
give to the Optionee any right or status of any kind as a stockholder of the
Company in respect of any shares of Common Stock covered by this Option or
entitle the Optionee to any dividends or distributions thereon unless and until
such shares shall have been delivered to the Optionee and registered in the
Optionee's name.

         11.     Interpretation.  If and when questions arise from time to time
as to the intent, meaning or application of the provisions hereof or of the
Plan, such questions shall be decided by the Board of Directors or the
Committee in its sole discretion, and any such decision shall be conclusive and
binding on the


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Optionee.  The Optionee hereby agrees that this Option is granted and accepted
subject to such condition and understanding.

         12.     Investment Representation.  At such time or times as the
Optionee may exercise this Option, the Optionee shall, upon the request of the
Company, represent in writing (i) that the shares being acquired by the
Optionee will not be sold except pursuant to an effective registration
statement, or applicable exemption from registration, under the Securities Act
of 1933, as amended, (ii) that it is the Optionee's intention to acquire the
shares being acquired for investment only and not with a view to distribution
thereof, and (iii) other customary representations as the Company deems
necessary or advisable.  No shares will be issued unless and until the Company
is satisfied as to the accuracy of such representations.

         13.     Withholding of Taxes.  Upon exercise of this Option (either
wholly or in part), the Optionee must pay to the Company, or make arrangements
satisfactory to the Company regarding payment of, any federal, state or local
taxes of any kind required to be withheld in connection with the issuance to
the Optionee of Common Stock upon exercise of this Option.

         14.     Notices.  All notices and other communications hereunder shall
be in writing and shall be deemed to have been duly given if delivered
personally, mailed certified mail (return receipt requested) or sent by
overnight delivery service, cable, telegram, facsimile transmission or telex to
the Optionee at the address on the signature page hereof and to the Company at
the address set forth below or at such other addresses as shall be specified by
the parties by like notice:

                 HighwayMaster Communications, Inc.
                 1155 Kas Drive
                 Richardson, TX  75081
                 Fax:  (972) 301-2263
                 Attn:  Secretary & General Counsel

         15.     Defined Terms.  All capitalized terms used herein and not
otherwise defined shall have the meanings given them in the Plan.

         16.     Confidentiality.  Unless otherwise permitted by the Chairman
of the Board or the President of the Company, Optionee agrees to keep
confidential the terms of this Option Agreement (and the terms



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of any other Option Agreement with any other employee of the Company known to
Optionee) and shall not disclose such terms to any other employee or otherwise.

         17.     Specified Information.  This Option Agreement shall apply with
respect to the following specific information:

                 a.       Date of Grant: SEPTEMBER 18, 1998

                 b.       Name of Optionee: JANA AHLFINGER BELL

                 c.       Number of Shares Covered by Option: 30,000

                 d.       Option Exercise Price Per Share:  $1.00

IN WITNESS WHEREOF, the undersigned have executed this Option Agreement to be
effective as of the Date of Grant set forth above.

                                      HIGHWAYMASTER COMMUNICATIONS, INC.

                                      By: /s/ J. RAYMOND BILBAO
                                          --------------------------------
                                      Name: J. Raymond Bilbao
                                           -------------------------------
                                      Title: General Counsel & Secretary
                                            ------------------------------


                                         /s/ JANA AHLFINGER BELL           
                                      ------------------------------------
                                      JANA AHLFINGER BELL, Optionee



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