Images Dated 11th February 1999

Man holding a mobile telephone to his ear

Mobile telephone. View of a man holding a mobile or cellular telephone to his ear. These telephones use low- power radio signals to transmit to a base station in the user's local area, or cell. A wide range of frequencies are used in each cell because the signals are too weak to interfere with those in other cells. Base stations relay calls to switching centres, from where calls can be transferred to other base stations, to the conventional telephone exchange, or to satellite stations for international calls

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