Telephone communication

Telephone communication has greatly advanced since 1945. By the mind-1950s, almost all telephone exchanges were automatic: users could dial local numbers for themselves without the aid of an operator. Direct dialling was extended to long-distance calls in the 1960s and overseas calls in the 1970s.
Today, the world-wide telephone system can justifiably be called the world´s largest machine. Its parts are linked together not only by wire cables, but also by rádio, satellites, and fiber optics.
In the 1980s, cellular telephones came into wide use.These require no connection to wires because they are linked by rádio to the nearest antenna tower. Mobile radiotelephones had existed since the 1950s, but they required the user to be within a few miles of a particular tower. Cellular phones, by contrast, divide the country into cells, each served by its own tower, and cellular phones are automatically “handed off” fro one cell to the next as the user moves around. Thus, cellular phones work almost anywhere.

By Andreia