GSM.Global System for Mobile Communications

GSM (Global System for Mobile communication) is a digital mobile network that is widely used by mobile phone users in Europe and other parts of the world. GSM uses a variation of time division multiple access (TDMA) and is the most widely used of the three digital wireless telephony technologies: TDMA, GSM and code-division multiple access (CDMA). GSM digitizes and compresses data, then sends it down a channel with two other streams of user data, each in its own time slot. It operates at either the 900 megahertz (MHz) or 1,800 MHz frequency band.

GSM, together with other technologies, is part of the evolution of wireless mobile telecommunications that includes High-Speed Circuit-Switched Data (HSCSD), General Packet Radio Service (GPRS), Enhanced Data GSM Environment (EDGE) and Universal Mobile Telecommunications Service (UMTS).

History
Predecessors to GSM, including Advanced Mobile Phone Service (AMPS) in the U.S. and Total Access Communication System (TACS) in the U.K., were built with analog technology. However, these telecommunications systems were unable to scale with the adoption of more users. The shortcomings of these systems signaled the need for a more efficient cellular technology that could also be used internationally.

To achieve that goal, in 1983, the European Conference of Postal and Telecommunications Administrations (CEPT) set up a committee to develop a European standard for digital telecommunications. CEPT decided on several criteria that the new system must meet: international roaming support, high speech quality, support for hand-held devices, low service cost, support for new services and Integrated Services Digital Network (ISDN) capability.

In 1987, representatives from 13 European countries signed a contract to deploy a telecommunications standard. The European Union (EU) then passed laws to require GSM as a standard in Europe. In 1989, the responsibility of the GSM project was transferred from CEPT to the European Telecommunications Standards Institute (ETSI).

Mobile services based on GSM were first launched in Finland in 1991. That same year, the GSM standard frequency band was expanded from 900 MHz to 1,800 MHz. In 2010, GSM represented 80% of the global mobile market. However, several telecommunications carriers have decommissioned their GSM networks, including Telstra in Australia. In 2017, Singapore retired its 2G GSM network.