Global System for Mobile Communications

Global System for Mobile Communications (GSM) is one of the major standards for digital mobile communications.

History
In 1982, the (now ) was formed by the  (CEPT) to design a pan-European mobile technology. GSM was named after the "Groupe de travail Spéciale pour les services Mobiles" group of CEPT that wrote the first GSM specifications.

By 2011, GSM was in use in over 60 countries and serving over six billion subscribers. The 2G GSM standard uses the 900, 1800, and 1900 MHz bands. allows packet-switched data communications over GSM, and is widely used for web and electronic mail access from mobile devices.

UMTS
The Universal Mobile Telecommunications System is based on GSM, and used as a successor technology by AT&T's 3G network. The iPhone 3G was the first device from Apple to utilize it.

Retirement of 3G service
AT&T is scheduled to shut down its GSM-based 3G network in February 2022 to make room for more advanced wireless services in the United States. T-Mobile will shut down its UMTS network on July 1, 2022. Both shutdowns will also affect early 4G phones that do not support (iPhone 5C, 5S and earlier). This will also affect the 3G-enabled original iPad and iPad 2.