... ,Optimized call route,SMS functions,Caller's ID. GSM WIRELESS PBX GSM WIRELESS PBX Feature: PBXs, a popular technology in the past ... 20 years, were welcome by group customers, which offered best solutions ... . But today’s PSTN, which include fixed line PSTN, wireless CDMA PSTN, wireless GSM PSTN, NGN PSTN etc., are greatly different from ...