The shield is based around the SIM900 GSM/GPRS radio module, and is compatible with the SIM908 GSM/GPRS module that adds a GPS receiver. Also on board this shield are a pair of 1/8″ audio ...

This tasty proof-of-concept cellular sandwich is made by adding a Sim900 GSM/GPRS module, which communicates via UART, to the Pi/TFT hardware while using a piece of foam core board in the middle ...