Telephone is an instrument that sends and receives voice messages in the form of electrical or radio signals. It is one of our most valuable means of communication. In just a few seconds, you can telephone a person across the street or on another continent. Alexander Graham Bell, a Scottish-born teacher of the deaf, patented the telephone in 1876. The word telephone comes from two Greek words meaning far and sound.
A telephone enables people to talk with each other at distances beyond the range of the human voice. More sophisticated telephones can send and receive not only voice messages but also written words, songs, drawings, photographs, and video.
Telephones are connected through a vast, complex communication network. The network includes large computers, tremendous lengths of copper wire and hair-thin glass fibers, cables buried in the ground and laid along the ocean floor, radio transmitters and receivers, and artificial satellites orbiting far above Earth.
Many telephones connect with the communication network by means of wires that run through the walls of buildings. Usually, a small clip connects a telephone to the wiring. Other phones, called wireless telephones or mobile telephones, are not wired to the network but rather are linked to it via radio signals.
