Glossary

GSM

Acronym for Global System for Mobile Communications, which is a 2G (second generation) standard for digital cellular communications. It is based on narrowband TDMA (Time Division Multiple Access), which allows eight simultaneous calls on the same radio frequency. GSM was first introduced in 1991 in Europe, but nowadays it is used worldwide and is one of the main 2G digital wireless standards. Most GSM networks operate in 900 MHz or 1800 MHz frequency bands with the exception of some networks in parts of the Americas, including the USA and Canada, that operate in 850 MHz and 1900 MHz. A key feature of GSM is the Subscriber Identity Module (SIM), commonly known as a SIM card. It contains the user's account information and phonebook, thus allowing the user to retain his information after switching handsets. SIM cards can be programmed to display custom menus for personalized services.