Measuring just 22 x 22 x 3 mm, the GE865-QUAD M2M GSM/GPRS module uses quad-band technology, allowing it to operated on all of the global GSM networks and makes all of the various data services ...

If you are looking for a compact GSM/GPRS module, you can get the SIM800L from most eBay traders. It is not the most judicious choice, but you can build your own basic GSM projects with a cheap modem ...