It is a device capturing and controling all the signals, which are being created by the whole system, especially the made and received phone call signals. The device is mostly used for connecting regular phone system with the Internet and backwards.
Portech MV-374 is a 4-channel VoIP-GSM gateway, which is responsible for converting GSM signal into VoIP (SIP) protocol. Used as a terminal server to route incoming calls from GSM network operators, VoIP communication, as well as a device for switching IP PBX, protocol-based SIP (RFC2543, RFC3261) with GSM. The device is compatible with IP PBX Asterisk, Elastix, Trixbox, Free PBX and registered on the SIP-server as a terminal device.