1.gsm modem, rs485 modem 2.with standard TCP/IP protocol stack, i/o 3.Support transparent ... /IP modem, Support transparent data transfe, gprs ip modem, gsm modemgprs modem with rs232 rs485 io for m2m meter readinggprs modem(DTU ... SMA female interface, 50 ohm, lighting protection(optional)SIM/UIMStandard 3V/1.8V user card interface, 15KV ESD protectionPowerTerminal block interface, reverse-voltage ...