Strong interface capacity,Optimized call route,SMS functions,Caller's ID, ... been working on R&D and manufacturing of PBX for 8 years. One year ago, we rolled ... PSTN, CDMA, GSM, and IP networks.2. Optimized call route: can access to different networks CDMA, GSM, ... make international calls while enjoying local call payment, and make free call for company’s internal communication between different cities ...