CMU-B21 Universal signaling unit, includes signal module for AMPS, TDMA, GSM/ GPRS/ EGPRS If you have these used products in stock, pls email to me ( buyer2@ jetest.cn) Tel: + 86-0755-8362-1889 Fax: + 86-0755-8362-8677 Mobiles: + 86-137-2425-0404