Dr Martin Cooper, a former general manager for the systems division at Motorola, is considered the inventor of the first modern portable handset. Cooper made the first call on a portable cell phone to his rival, Joel Engel, head of research at Bell Laboratories.

Bell had introduced the idea of cellular communications in 1947 with their police car technology and had been racing to beat Motorola. But in the end Motorola was first to incorporate the technology into a portable device designed for use outside a vehicle.

By 1977 AT&T and Bell Labs had constructed a prototype cellular system. A year later, public trials of the new system started in Chicago with over 2,000 test customers. In 1981 Motorola and American Radio telephone started a second U.S. test in the Washington/Baltimore area. By 1982 the slow-moving FCC finally authorised commercial cellular services in the USA.

In the mid 1970s, it was the radiopager that marked out the busy professional on the move.

Radiopagers were a stepping stone to mobile communications - call alerts and short messages could reach you if you were in range of a radio transmitter - but you still needed to find a telephone to return the call.

Surveys carried out by the Post Office in 1968 showed that Britain was ready for wide area radio paging. The first system was introduced in 1973, covering the Thames Valley. It was extended to London in 1976. By the end of the 1970s, most of Britain was covered by several networks.

The reign of the pager as the primary form of mobile communications lasted into the early 1990s. By then, mobile phones had made the pager almost obsolete.