... 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( ...