The SIM808 GSM GPRS Module is at the heart of our Adafruit FONA 808 - Mini Cellular GSM + GPS Breakout. For people who want to integrate a cellular (GSM/GPRS) module into their design without the full breakout, this hand-solderable module is pretty nice! Please note we don't provide any tech support for this module, but we do have a schematic as well as a collection of datasheets and app notes that can be used to interface.