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