During the early 1980s, the first generation of analogue cellular telephone systems were experiencing rapid growth in Europe. Each country had developed its own system, which was incompatible with everyone else's in equipment and operation. Mobile equipment was limited to operation within national boundaries, and there was a very limited market for each type of equipment, so economies of scale, and the subsequent savings, could not be realized.

The European operators devised a new digital system which they called GSM (Global System for Mobile Communications), and this became known as the 'second generation' or 2G mobile communications service. Commercial 2G services started in mid 1991, and at the beginning of 2002 there were more than 662 million GSM users, accounting for approximately 70% percent of the world digital wireless market.

GSM operates at two frequencies, 900MHz and 1800 MHz (1900 MHz in the USA). The antenna for a 900MHz transmitter is typically 150 cm tall, 20 cm wide and 10 cm deep. It is actually a long, thin fibreglass box containing about a dozen small aerials. An 1800 MHz antenna can be about half this size, but covers a smaller area. Most new GSM installations are 1800 MHz.

GSM has always been able to provide slow data services. The UK networks are being upgraded with a system called GPRS which offers high data rate internet connections from a GSM phone. A higher signal strength is needed for good data services, and the operators are still adding base stations to their networks to improve coverage.

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