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This article describes the functional components of the modern telephone and traces the historical development of the telephone instrument. In addition it describes the development of what is known as the public switched telephone network (PSTN).
In the 1870s two American inventors, Elisha Gray and Alexander Graham Bell, each independently, designed devices that could transmit speech electrically. Gray’s first device made use of a harmonic telegraph, the transmitter and receiver of which consisted of a set of metallic reeds tuned to different frequencies.
Alexander Graham Bell, Scottish-born American inventor, scientist, and teacher of the deaf whose foremost accomplishments were the invention of the telephone (1876) and refinement of the phonograph (1886). He also worked on use of light to transmit sound, development of a metal detector, and heavier-than-air flight.
The earliest telephone instrument to see common use was introduced by Charles Williams, Jr., in 1882. Designed for wall mounting, this instrument consisted of a ringer, a hand-cranked magneto (for generating a ringing voltage in a distant instrument), a hand receiver, a switch hook, and a transmitter.
mobile telephone, portable device for connecting to a telecommunications network in order to transmit and receive voice, video, or other data. Mobile phones typically connect to the public switched telephone network (PSTN) through one of two categories: cellular telephone systems or global satellite-based telephony.
Telegraph, any device or system that allows the transmission of information by coded signal over distance. The term most often refers to the electric telegraph, which was developed in the mid-19th century and for more than 100 years was the principal means of transmitting printed information.
The U.S. patent granted to Alexander Graham Bell in 1876 for developing a device to transmit speech sounds over electric wires is often called the most valuable ever issued. Within 20 years the telephone acquired a form that would remain fundamentally unchanged for decades.
The iPhone is a smartphone produced by Apple Inc. that combines mobile telephone, digital camera, music player, and personal computing technologies. After more than two years in development, the device was first released in the United States in 2007.
From the earliest days of the telephone, it was observed that it was more practical to connect different telephone instruments by running wires from each instrument to a central switching point, or telephone exchange, than it was to run wires between all the instruments.
Telephone service across the Atlantic Ocean began in 1927. The first cell phones appeared in the late 1970s. At about the same time advances in electronics made telephones useful for more than just talking. Fax machines became common in the 1970s. They use telephone wires to send words and pictures.