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. BCGII Foreign Sales Corp. Barbados BCGII Foreign Sales Corp. 5. Wireless Roaming, Inc. Delaware Boston Communications Group 6. BCGI Communications Corp. Delaware Boston Communications Group