... Power, Ready, Status, WAN, PC, GSM Call forward from GSM to VoIP and VoIP to GSM ... Mechanismdraft-ietf-sipping-cc-transfer-04 Session Initiation Protocol Call Control - TransferCodec: G.711 (A/µ law), ... SIP/H323 platform, GOIP4, 4 SIM cards 1. Call forward:Description: Someone is in China, but all ... phone, this can save a lot of international call fee.2, Call backDescription: User A uses the normal ...