EXHIBIT 21 SUBSIDIARIES OF REGISTRANT NAMES UNDER WHICH PLACE OF INCORPORATION DOING BUSINESS ---------------------- --------------------------- 1. Voice Systems Technology Inc. Delaware Boston Communications Group 2. Cellular Express, Inc. Massachusetts Boston Communications Group 3. BCG Securities Corp. Massachusetts Boston Communications Group 4. BCG Foreign Sales Corp. U.S. Virgin Islands BCG Foreign Sales Corp. 5. BCG de Mexico, S.r.l. Mexico Boston Communications Group