GSM, first introduced in 1991, is the leading digital cellular system. It uses narrowband TDMA (Time Division Multiple Access). Eight simultaneous calls can occupy the same radio frequency. GSM simplifies data transmission to allow laptop and palmtop computers to be connected to GSM phones. It provides integrated voice mail, high-speed data, fax, paging and Short Message Services (SMS) capabilities, as well as secure communications. It offers the best voice quality of any current digital wireless standard.
