Quad Band 1xGSM SIM Gateway Converter SIP IP Phone Adapter+FREE LCD USB Voltage&Current Meter Tester Support dual protocols: ITU-H.323 V4 and IETF SIP V2 GSM module for making GSM calls,VAD,CNG,EC Provide 1 Sim Card ports for GSM extensions Support G.711 Alaw/ULaw, G.729A/B, G.723.1 Codecs,router function Support Multiple dial plans and line hun,QoS,NAT transversal