EXHIBIT 10.28

                                  AMENDMENT TO
                      CDPD SERVICE AND EQUIPMENT AGREEMENT


         This   Amendment  to  CDPD  Service  and  Equipment   Agreement   (this
"Amendment"),  dated this 9th day of September,  1998 and effective as of August
18, 1998 (the "Effective Date"),  amends that certain CDPD Service and Equipment
Agreement  (the   "Agreement")   between  GTE  Mobile   Communications   Service
Corporation  ("GTEMC") and U.S. Wireless Data, Inc. ("Customer") dated August 1,
1997.

         GTEMC and Customer hereby agree as follows:

1.       Substitution of Party. GTE Mobile  Communications  Service  Corporation
         assigned  its interest in the  Agreement  to GTE Wireless  Incorporated
         ("GTEW"),  an  affiliate of GTEMC,  as of January 1, 1998.  Pursuant to
         Section  10F  of  the  Agreement,   this  assignment  did  not  require
         Customer's  consent.  Accordingly,  GTEW has  assumed  all  rights  and
         responsibilities  of GTEMC under the Agreement and has been substituted
         for  GTEMC  therein,  and  GTEMC  no  longer  has any  interest  in the
         Agreement.  In the Agreement,  the term "GTEMC" in every instance means
         GTEW.

2.       Exhibit B. Exhibit B is hereby amended by removing  Sections 2, 3 and 4
         thereof in their  entirety.  The pricing in Section 1 is hereby deleted
         in its entirety  and  replaced  with the pricing set forth in Section 4
         (the  "Alternate  Rate Plan").  The Alternate Rate Plan provides for an
         activation  fee of  $15.00,  a monthly  minimum of $9.00,  75  included
         kilobytes  and a $.09 charge for  kilobytes  in excess of the  included
         kilobytes.

3.       Conversion of Existing  NEIs.  The parties agree that all of Customer's
         NEIs  currently  existing on the MERCHT rate plan will be  converted to
         the Alternate Rate Plan as of the Effective Date. Further,  the parties
         agree  that all NEIs  added  after  the  Effective  Date will be billed
         according to the Alternate Rate Plan.

4.       Exhibit C.  Section 4 of Exhibit C is hereby  amended by  removing  the
         second paragraph of such section in its entirety.

5.       Reaffirmation  of Other Terms and Conditions.  All terms and conditions
         not expressly  amended  hereby  remain  unchanged and in full force and
         effect,  and the parties ratify and reaffirm such terms as if they were
         set forth in full herein.
<PAGE>


This 9th day of September, 1998.


GTE WIRELESS INCORPORATED                            U.S. WIRELESS DATA, INC.


By: /s/ Byron W. Smith                               By:   /s/ Rod Stambaugh  
-------------------------------                         -------------------- 
Print Name:  Byron W. Smith                          Print Name:  Rod Stambaugh
Title: Vice President - Sales                        Title:  President  


By:  /s/ Catherine H. La Fiandra            
     ---------------------------            
Print Name: Catherine H. La Fiandra            
Title: Asst. Secretary                   


                                       -2-