2G NETWORKS

2G (or 2-G) is short for second-generation wireless telephone technology.

The main differentiator to previous mobile telephone systems, retrospectively dubbed 1G, is that the radio signals that 1G networks use are analog, while 2G networks are digital. Both systems use digital signaling to connect the radio towers (which listen to the handsets) to the rest of the telephone system.


2G technologies

2G technologies can be divided into TDMA-based and CDMA-based standards depending on the type of multiplexing used. The main 2G standards are:

* GSM (TDMA-based), originally from Europe but used worldwide (Time Division Multiple Access)
* iDEN (TDMA-based), proprietary network used by Nextel in the United States and Telus Mobility in Canada
* IS-136 aka D-AMPS, (TDMA-based, commonly referred as simply TDMA in the US), used in the Americas
* IS-95 aka cdmaOne, (CDMA-based, commonly referred as simply CDMA in the US), used in the Americas and parts of Asia
* PDC (TDMA-based), used exclusively in Japan

2G services are frequently referred as Personal Communications Service, or PCS, in the United States.

2.5G services enable high-speed data transfer over upgraded existing 2G networks. Beyond 2G, there's 3G, with higher data speeds, and 4G, with even higher data speeds, to enable new services for subscribers, such as picture messaging and video telephony.