The GPRS/GSM Shield provides you a way to use the GSM cell phone network to receive data from a remote location，it delivers GSM/GPRS 850/900/1800/1900MHz signals for Audio, SMS and GPRS Service. It is compatible with all boards which have the same form factor (and pinout) as a standard Arduino Board. This GPRS/GSM shield is configured and controlled via its UART using AT commands. The GPRS Shield Also has 6 GPIOs,2 PWMs and 1 ADC(They are all 2V8 logic), which can be controlled by AT commands of Controller.