The concept of cellular telephony was first articulated in 1947 by D. H. Ring, in a Bell Labs Technical Memorandum that started with the prescient statement:

“an adequate mobile radio system should provide service to any equipped vehicle at any point in the whole country.”

The idea was to divide a large area into a grid of small zones called cells, each having a low-power transceiver to send and receive calls to mobile units within the cell. There would be automatic handoff from cell to cell and reuse of frequencies. The idea was visionary but the technology to implement it simply did not exist, and the bandwidth needed was not available. It lay dormant until the 1960s, when Joe Engel and Richard Frenkiel of Bell Labs leveraged computers and electronics to make it work. The first call from a handheld phone, however, was placed by their rival, Motorola's Martin Cooper, on April 3rd 1973, who –to the amazement of those passing by- phoned Engel while walking in New York. The handset weigthed 1 Kg and cost $4000. The first trial system was deployed by AT&T in Chicago in 1978 and went commercial in 1983. By 2011, there were 261,392 cells in the US alone.

(Richard Frenkiel's chronicle "Cellular dreams and cordless nightmares" can be downloaded here)