1. Global System for Mobile (GSM):
It is the most successful standard. It uses narrow band TDMA(Time Division Multiple Access), allows simultaneous calls on the same frequency range of 900 MHz to 1800 MHz. The network is identified using the SIM(Subscriber Identity Module).
2. GPRS (General Packet Radio Services):
It is a packet oriented mobile data service on the 2G on GSM. GPRS was originally standardized by European Telecommunications Standards Institute (ETSl) GPRS usage is typically charged based on volume of data transferred. Usage above the bundle cap is either charged per megabyte or disallowed.
3. EDGE(Enhanced Data rates for GSM Evolution):
It is three times faster than GPRS. It is used for voice communication as well as an internet connection.
4. Code Division Multiple Access (CDMA):
It is a channel access method used by various radio communication technologies. CDMA is an example of multiple access, which is where several transmitters can send information simultaneously over a single communication channel.
This allows several users to share a band of frequencies To permit this to be achieved without undue interference between the users, and provide better security.