SainSmart Small GSM GPRS SIM900 for Arduino UNO, Mega Can work with Arduino Uno; Only work for 2G network SainSmart is well known and provides high quality electronics product Embedded TCP/UDP stack - allows you to upload data to a web server Quad-Band 850/900/1800/1900 MHz - would work on GSM networks in all countries across the world Short Message Service - so that you can send small amounts of data over the network (ASCII or raw hexadecimal)