... modem, rs485 modem 2.with standard TCP/IP protocol stack, i/o 3.Support transparent data transfer 4. Support DDNS IP modem, RS232 modem ... , GSM IP modem, GPRS data modem, data terminal,GPRS DTU, TCP/IP modem, Support transparent data transfe, gprs ip modem, gsm modemgprs modem with rs232 rs485 ... io for m2m meter readinggprs modem(DTU) with ...