Global System for Mobile Communications (GSM)

An international standard for mobile networks, used by the 2G mobile phones. It is one of the leading digital cellular systems, available in more than 160 countries, and accounting for approximately 70% of the total digital cellular wireless market. GSM provides services such as voice-calling, data services and multimedia messaging. The most obvious feature of GSM is SIM cards.

The standard is used in three frequency bands – 900MHz, 1800MHz, and 1900MHz. In the UK, the term GSM is commonly used to mean GSM900, the 900 MHz digital frequency used by O2, Vodafone and the rest of Europe. PCN/DCS networks such as Orange and T-Mobile often refer to their digital 1800 MHz frequency as GSM 1800.

GSM uses narrowband TDMA, which allows eight simultaneous calls on the same radio frequency. It reaches a speed of 9.600 BIT/s and can thus not be used for bandwidth applications.