Adafruit FONA 808 Shield - Mini Cellular GSM + GPS for Arduino
Cellular + GPS tracking, all in one, for your Arduino? Oh yes! Introducing Adafruit FONA 808 GSM + GPS Shield, an all-in-one cellular phone module with that lets you add location-tracking, voice, text, SMS and data to your project, in Arduino shield format for easy use.
Sounds delicious, right? So Adafruit plated this fine module onto a shield with all the extras you need to make your next project shine
Onboard LiPoly battery charging circuitry so you can take your project on the go. Use any 500mAh+ LiPoly or LiIon battery and recharge via the Arduino when necessary. Two LEDs let you know when its charging and done. You can then flip the switch and use the battery to run your circuit!
As of August 26, 2015 Adafruit is shipping with the version 2 SIM808 module which has a slightly different GPS command naming system (AT+CGNS rather then AT+CGPS), and a newer GPS chipset (MT3337 not MT3336)
SIM800 Command Manual - All the basic commands that the module supports (please note some are not supported by the FONA 808, such as FM radio, external audio, or bluetooth)