The sim 300 and sim 300c are tri-band gsm /gprs (900 /1800 /1900 mhz) solution in a compact plug-in module. \n\nthey are compliant with gsm /gprs and tcp /ic protocols with stable property. sim 300c is with dip board-to-board connector, it is designed for vehicle application specifically. \n\ntechnical feature of sim 3xx series product is the same as siemens mc55 (tri-band), however, it is much cheaper than mc55.