HIGHWAYMASTER OFFERS PROMILES^® 99 INTEGRATION

DALLAS, Sept. 1, 1999 - HighwayMaster Communications, Inc. (NASDAQ: HWYM), the leading provider of wireless voice and data communications services to the commercial trucking and service vehicle industries, today announced that its HighwayMaster Corporation subsidiary and ProMiles Software Development Corporation (PSDC), developers of North America's largest and most accurate mileage database, have released the ProMiles^® 99 routing software integration with HighwayMaster's Series 5000 mobile communications system.

The Series 5000 provides both voice and data communications, combined with precise positioning through GPS (Global Positioning Satellite) technology. Optional features include EngineMaster^TM for engine performance monitoring, Michelle Wilde, Series 5000 Product Line Director of HighwayMaster, stated: MileMaster^® for turnkey automated fuel tax reporting and Rolling ETA^® for real-time, on-board, estimated-time-of-arrival calculations.

"The ProMiles integration offers our customers a cost-effective solution for viewing their tractors' status and location down to the street level, as well as the ability to easily send the route directions and fuel purchase plans to the drivers - all through the HighwayMaster system," said Michelle Wilde, HighwayMaster's Series 5000 product line director. "ProMiles 99 is the ideal choice for the integration, since it is one of the most comprehensive and competitively priced routing systems available today."

ProMiles 99 provides the largest and most accurate mileage database in North America, with over 805,000 miles of truck-usable roads and 965,000 accessible locations. Several options are available for ProMiles 99, including fuel purchase optimization, Canadian mapping and California Distance Table 8. PSDC plans to offer ProMiles 99 starting at $895 for a single user.

"We believe the HighwayMaster and ProMiles integration will assist customers in a number of ways," said Tony Stroncheck, PSDC president. "They can:

• Locate lost/stolen equipment quickly - in the US and Canada;
• View and plot the equipment's historical locations;
• Locate consignee by address;
• Send detailed routing instructions from ProMiles directly to the driver;
• Send optimized fuel purchase plan from ProMiles directly to the driver;
• Track equipment estimated time of arrival (ETA) more efficiently;
• Save time and money by eliminating out-of-route (OOR) miles.

We are confident that this integration can help trucking and service companies increase productivity and enhance customer satisfaction."

"We have been relying on the ProMiles and HighwayMaster interface since we began our initial testing," said Gary Krofchalk, Chief Financial Officer of Texas American Express. "We were looking for an affordable way to rate trips and route drivers. This advanced solution provides us with trip mileages and routing, locates our tractors and customer sites, and selects the best truck stops for our drivers. We've been extremely happy with the performance of the integrated HighwayMaster and ProMiles solution."

HighwayMaster is the leading nationwide mobile communications system provider of voice and data communications, combined with GPS vehicle location technology, for the trucking and service vehicle industries. Through strategic alliances, HighwayMaster has created one of the largest enhanced-cellular network in existence today, providing seamless wireless services in more than 99 percent of the available cellular coverage areas in the United States and 100 percent of the A-side cellular coverage areas in Canada. HighwayMaster sells and markets its system, which is currently covered by 22 issued U.S. Patents and other U.S. and international patents pending, throughout the United States and Canada.

ProMiles Software Development Corporation was founded by a unique combination of professional programmers, tax auditors, ICC practitioners and truck drivers who began working together in 1980. PSDC, with offices in Bridge City, Texas, Las Cruces, N.M., and Ontario, Canada, has developed FHWA, IFTA and IRP-compliant software used by over 5,800 customers in the U.S. and Canada, including over 70 percent of the Canadian Provinces, the majority of U. S. states/DOT auditors, and large corporations like Con-Way, General Motors, Hewlett-Packard, Penske Logistics, Ryder Logistics and Wal-Mart. PSDC also develops other quality desktop and online products such as ProMiles Fuel Tax and ProMilesOnline.

HighwayMaster is a federally registered trademark and service mark of HighwayMaster Communications, Inc. ProMiles is a federally registered trademark of Road Legal, Inc. and PSDC.

Legal notice to investors: Certain matters discussed in this press release are "forward-looking statements" intended to qualify for the safe harbors from liability established by the Private Securities Litigation Reform Act of 1995. These forward-looking statements can generally be identified as such because the context of the statement will include words such as the Company "expects," "anticipates" or words of similar import. Similarly, statements that describe the Company's future plans, objectives or goals are also forward-looking statements. Such forward-looking statements generally involve known and unknown risks, uncertainties and other facts which may cause the actual results, performance or achievements of the Company to be materially different from any future results, performance or achievements expressed or implied by such forward-looking statements. Such factors include, among others, the following: general economic and business conditions; competition; success of operating initiatives; development and operating costs; market conditions; advertising and promotional efforts; brand awareness; adverse publicity; acceptance of new product offerings; consumer trial and frequency; changes in business strategy or development plans; quality of management; availability, terms and development of capital; business abilities and judgment of personnel; availability of qualified personnel; labor and employee benefit costs; changes in, or the failure to comply with government regulations. Additionally, there can be no assurance that the Company=s ProMiles integration will allow trucking and service companies to increase productivity and customer satisfaction. For a listing of risks applicable to the future prospects of the Company, please refer to the reports filed with the SEC, such as recent 10-K and 10-Q Reports.

For more information, contact:

Todd Felker
Senior Vice President
Marketing and Sales
HighwayMaster Corporation
(972) 301-2024
www.highwaymaster.com

Tony Stroncheck
President
ProMiles Software
Development Corporation
US Corporate Office
(800) 324-8588
www.promiles.com

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