2G (or 2-G) is short for second-generation wireless telephone technology. It cannot normally transfer data, such as email or software, other than the digital voice call itself, and other basic ancillary data such as time and date. Nevertheless, SMS messaging is also available as a form of data transmissiom for some standards.
In the Americas this is called D-AMPS, or known just as digital cellular. In Europe, GSM is employed as 2G standard. Both GSM and D-AMPS use TDMA multiplexing. Another widely spread 2G standard in the Americas and in Asia is IS-95 also known as CDMA due to the multiplexing technology employed.