Sim 340, sim 340c and sim340d are complete quad-band gsm /gprs (850 /900 /1800 /1900 mhz) solution compliant with tcp /ip protocol. \n\nsim 340c is in a compact plug-in module with dip board-to-board connector and sim 340d is a complete quad-band solution in a smt module, which can save your trouble and money to buy connectors.\n\ntechnical feature of sim 3xx series product is the same as siemens mc55 (tri-band), however, it is much cheaper than mc55.