GPRS GSM GPS SIM808 Board for Arduino
Have you ever thought of making a portable tracking device? There is a module that is just right for this kind of project, the sim808 GPS/GPRS/GSM board.
This board uses the sim808 chip that supports Quad-Band 850/900 1800/1900 MHz. It has a low power consumption at around 1mA in sleep mode and can be supplied with 3.1v to 4.8v power. It has a logic level of 3.3V to 5V. It also supports the use of standard SIM card size.
The sim808 chip also supports the use of GPS NMEA (National Marine Electronics Association) protocol.
You can do what a regular phone could do, like sending/receiving an SMS, making/taking a call, connecting to GPRS(data) for internet usage. You could use this if you want to make a DIY mobile phone.
This board is a GPRS Class B meaning it could only do one service (GPS/GPRS) at a time. To elaborate, you could receive/make calls, or send/receive an SMS during a GPRS connection but the GPRS service is suspended and resumes once done with call/SMS.