Mobile telephony is the provision of telephone services to phones which may move around freely rather than stay fixed in one location. Mobile phones connect to a terrestrial cellular network of base stations (cell sites), whereas satellite phones connect to orbiting satellites. Both networks are interconnected to the public switched telephone network (PSTN) to allow any phone in the world to be dialled.
In 2008 there were 4.1 billion mobile cellular subscriptions in the world
The history of mobile phones begins with early efforts to develop radio telephone technology and from two-way radios in vehicles and continues through emergence of modern mobile phones and associated services.
Radiophones have a long and varied history going back to Reginald Fastener's invention and shore-to-ship demonstration of radio telephony, through the Second World War with military use of radio telephony links and civil services in the 1950s, while hand-held mobile radio devices have been available since 1973. Mobile phone history is often divided into generations (first, second, third and so on) to mark significant step changes in capabilities as the technology improved over the years.
Mobile phones send and receive radio signals with any number of cell site base stations fitted with microwave antennas. These sites are usually mounted on a tower, pole or building, located throughout populated areas, then connected to a cabled communication network and switching system. The phones have a low-power transceiver that transmits voice and data to the nearest cell sites, normally not more than 8 to 13 km (approximately 5 to 8 miles) away. In areas of low coverage, a cellular repeater may be used, which uses a long distance high-gain dish antenna or yogi antenna to communicate with a cell tower far outside of normal range, and a repeater to rebroadcast on a small short-range local antenna that allows any cellphone within a few meters to function properly.
When the mobile phone or data device is turned on, it registers with the mobile telephone exchange, or switch, with its unique identifiers, and can then be alerted by the mobile switch when there is an incoming telephone call. The handset constantly listens for the strongest signal being received from the surrounding base stations, and is able to switch seamlessly between sites. As the user moves around the network, the "hand offs" are performed to allow the device to switch sites without interrupting the call.
In 1956, the first fully automatic mobile phone system, called MTA (Mobile Telephone system A), was developed by Ericsson and commercially released in Sweden. This was the first system that did not require any kind of manual control in base stations, but had the disadvantage of a phone weight of 40 kg (90 lb). MTB, an upgraded version with transistors, weighing 9 kg (20 lb), was introduced in 1965 and used DTMF signaling. It had 150 customers in the beginning and 600 when it shut down in 1983.
The first person to have a mobile phone in the United Kingdom was reputedly Prince Philip, who had a system fitted into the trunk of his Aston Martin in 1957. The Prince could make phone calls to the Queen while driving, which was thought to be quite amazing at the time. The Duke of Gloucester heard about the mobile phone and tried to obtain one, but the Post Office denied his request.
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