Juvtmall ( a company supply PCB PrototypingPCBA service and sell kinds of components, modules and so on) 

The SIM808 GPRS/GSM+GPS Shield V1.0 is based on the chip named SIM808, it communicates with Catduino Uno via pins (RX, TX) with GPS data and GPRS data. For the operate voltage could either at 3.3V or 5V, it can be totally compatible to the Arduino. It can be also used to making/answering call, sending/receiving SMS messages and local the position. By the way, SIM GPRS/GSM+GPS Shield V1.0 suppose an SIM card holder at the opposite side.



Arduino learning notebook -- What is Arduino? (VOL. 2)

5. The design of PCB--design considerations and assembly rules

1. The design of PCB--- brief introduction and design steps