... local or internet7,Field proven compatible with Asterisk-based softswitches ModelSinoV-508SGSinoV-508SCSinoV-508WNumber of Channels8GSM ... , NAT, Telnet, HTTP, FTP, TFTPConfiguration and Maintenance·Web-based GUI·Console, Telnet command line·Centralized network managementFirmware UpdateLocal file ... 50ºC·Operating humidity: 10 – 90%Warranty12 MonthsWEB:Application:1,GSM to VOIP and VOIP to GSM2,diagram: ...