1,RoIP Gateway,VoIP phone,gsm voip 2,Build in GSM/CDMA Module 3,Point-to-Point Mode ... Mode 4,Link up radio RoIP Gateway,VoIP phone,GSM VoIP Description:What is a Cross-Network Gateway? ... communicate with the radio network via a PSTN or GSM phone.A PTT user can make and receive calls via ... direct access to the radio networks connected via any phone in the existing telephone networks (PSTN and Cellular). ...