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Early history
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Digital telephones and voice over IP
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From Wikipedia, the free encyclopedia
"Phone" redirects here. For the handheld personal computer, see Smartphone. For other uses, see Phone (disambiguation) and Telephone (disambiguation).
AT&T push button telephone made by Western Electric, model 2500 DMG black, 1980
Telephone
An old rotary dial telephone
Inventor Alexander Graham Bell
Inception 1876; 148 years ago
A telephone is a telecommunications device that permits two or more users to conduct a conversation when they are too far apart to be easily heard directly. A telephone converts sound, typically and most efficiently the human voice, into electronic signals that are transmitted via cables and other communication channels to another telephone which reproduces the sound to the receiving user. The term is derived from Greek: τῆλε (tēle, far) and φωνή (phōnē, voice), together meaning distant voice. A common short form of the term is phone, which came into use early in the telephone's history.[1] Nowadays, phones are almost always in the form of smartphones or mobile phones, due to technological convergence.
In 1876, Alexander Graham Bell was the first to be granted a United States patent for a device that produced clearly intelligible replication of the human voice at a second device.[2] This instrument was further developed by many others, and became rapidly indispensable in business, government, and in households.
The essential elements of a telephone are a microphone (transmitter) to speak into and an earphone (receiver) which reproduces the voice at a distant location.[3] The receiver and transmitter are usually built into a handset which is held up to the ear and mouth during conversation. The transmitter converts the sound waves to electrical signals which are sent through the telecommunication system to the receiving telephone, which converts the signals into audible sound in the receiver or sometimes a loudspeaker. Telephones permit transmission in both directions simultaneously.
Most telephones also contain an alerting feature, such as a ringer or a visual indicator, to announce an incoming telephone call. Telephone calls are initiated most commonly with a keypad or dial, affixed to the telephone, to enter a telephone number, which is the address of the call recipient's telephone in the telecommunication system, but other methods existed in the early history of the telephone.
The first telephones were directly connected to each other from one customer's office or residence to another customer's location. Being impractical beyond just a few customers, these systems were quickly replaced by manually operated centrally located switchboards. These exchanges were soon connected together, eventually forming an automated, worldwide public switched telephone network (PSTN). For greater mobility, various radio systems were developed for transmission between mobile stations on ships and automobiles in the mid-20th century. Hand-held mobile phones were introduced for personal service starting in 1973. In later decades, their analog cellular system evolved into digital networks with greater capability and lower cost.
Early history
Main article: History of the telephone
Further information: Invention of the telephone and Elisha Gray and Alexander Bell telephone controversy
Alexander Graham Bell's Telephone Patent Drawing
Replica of the telettrofono, invented by Antonio Meucci and credited by several sources as the first telephone[4]
Bell placing the first New York to Chicago telephone call in 1892
Before the development of the electric telephone, the term telephone was applied to other inventions, and not all early researchers of the electrical device used the term. Perhaps the earliest use of the word for a communications system was the telephon created by Johann Sigismund Gottfried Huth in 1796. Huth proposed an alternative to the optical telegraph of Claude Chappe in which the operators in the signaling towers would shout to each other by means of what he called "speaking tubes", but would now be called giant megaphones.[5] A communication device for sailing vessels, called telephone, was invented by Captain John Taylor in 1844. This instrument used four air horns to communicate with vessels in foggy weather.[6][7]
Johann Philipp Reis used the term in reference to his invention, commonly known as the Reis telephone, in c.1860. His device appears to be the first device based on the conversion of sound into electrical impulses
