Model GOIP-1 Hybertone VoIP GSM Gateway GOIP-1 1 Port for call termination (VoIP to GSM) and origination (GSM to VoIP). It is SIP&H.323 based and compatible with Asterisk, Trixbox, 3CX, SIP Proxy Server, VoipBuster. It can enable to make 1/4/8/16 calls simultaneously from IP phones to GSM networks and GSM networks to IP phone. Our GoIPs come with all the common network, VoIP, and GSM features and they have been widely tested for compatibility, stability, and reliability. In addition, we've developed our proprietary Remote SIM technology for SIM card management without inserting SIM cards to GoIPs. Together with the SMS Server and SIM Sever, you can now build your own system for voice traffics between VoIP and GSM or a SMS Messaging system based on your application requirements. In addition, each GoIP is equipped with a Remote Control client which enables a secure remote access method for technical support and GoIP management. All of the above features are available at no additional charges