A telephone is a telecommunications device that permits two or more users to conduct a conversation when they are too far apart to be 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 and φωνή, together meaning distant voice. A common short form of the term is phone, which came into use almost immediately after the first patent was issued.
Pulse dialing is a signaling technology in telecommunications in which a direct current local loop circuit is interrupted according to a defined coding system for each signal transmitted, usually a digit. This lends the method the often used name loop disconnect dialing. In the most common variant of pulse dialing, decadic dialing, each of the ten Arabic numerals are encoded in a sequence of up to ten pulses. The most common version decodes the digits 1 through 9, as one to nine pulses, respectively, and the digit 0 as ten pulses. Historically, the most common device to produce such pulse trains is the rotary dial of the telephone, lending the technology another name, rotary dialing.
In telephony, on-hook and off-hook are two states of a communication circuit. On subscriber telephones the states are produced by placing the handset onto or off the hookswitch. Placing the circuit into the off-hook state is also called seizing the line. Off-hook originally referred to the condition that prevailed when telephones had a separate earpiece (receiver), which hung from its switchhook until the user initiated a telephone call by removing it. When off hook the weight of the receiver no longer depresses the spring-loaded switchhook, thereby connecting the instrument to the telephone line.
A telephone call is a connection over a telephone network between the called party and the calling party.
Elisha Gray was an American electrical engineer who co-founded the Western Electric Manufacturing Company. Gray is best known for his development of a telephone prototype in 1876 in Highland Park, Illinois. Some recent authors have argued that Gray should be considered the true inventor of the telephone because Alexander Graham Bell allegedly stole the idea of the liquid transmitter from him. Although Gray had been using liquid transmitters in his telephone experiments for more than two years previously, Bell's telephone patent was upheld in numerous court decisions.
A cordless telephone or portable telephone is a telephone which has a portable handset but which one can use like landline phone communication; such telephones operate using radio-frequency transmission rather than a physical insulated wire or a direct connection to a telephone line. A cordless telephone's base station connects with the telephone network through a telephone line and also includes a charger to charge the handset's batteries. The operational range is limited, usually to the same building or within some short distance from the base station.
The Western Electric model 500 telephone series was the standard domestic desk telephone set issued by the Bell System in North America from 1950 through the 1984 Bell System divestiture. Millions of model 500-series phones were produced and were present in most homes in North America. Many are still in use today because of their durability and ample availability. Its modular construction compared to previous types simplified manufacture and repair, and facilitated a large number of variants with added features.
The model 202 telephone was a desktop telephone produced by Western Electric for the Bell System from 1930 to 1939, and by Northern Electric in Canada. Refurbished units were installed into the mid-1950s. It was an updated version of the 102-type telephone, containing the newly developed anti-sidetone circuitry to reduce electronic feedback from the transmitter (mouthpiece) to the receiver (earpiece).
On analog telephone lines with special services, a flash or register-recall signal is used to control functions on the public telephone exchange, PBX or VoIP ATA.
The invention of the telephone was the culmination of work done by many individuals, and led to an array of lawsuits relating to the patent claims of several individuals and numerous companies.
The carbon microphone, also known as carbon button microphone, button microphone, or carbon transmitter, is a type of microphone, a transducer that converts sound to an electrical audio signal. It consists of two metal plates separated by granules of carbon. One plate is very thin and faces toward the speaking person, acting as a diaphragm. Sound waves striking the diaphragm cause it to vibrate, exerting a varying pressure on the granules, which in turn changes the electrical resistance between the plates. Higher pressure lowers the resistance as the granules are pushed closer together. A steady direct current is passed between the plates through the granules. The varying resistance results in a modulation of the current, creating a varying electric current that reproduces the varying pressure of the sound wave. In telephony, this undulating current is directly passed through the telephone wires to the central office. In public address systems it is amplified by an audio amplifier. The frequency response of most carbon microphones, however, are limited to a narrow range, and the device produces significant electrical noise.
This history of the telephone chronicles the development of the electrical telephone, and includes a brief overview of its predecessors. The first telephone patent was granted to Alexander Graham Bell in 1876.
The General Post Office (GPO) of the United Kingdom carried the sole responsibility for providing telecommunication services across the country with the exception of Hull. The GPO issued a range of telephone instruments to telephone service subscribers that were matched in function and performance to its telephone exchanges.
The model 102 telephone was a version of Western Electric's first widely distributed telephone set that featured the transmitter and receiver in a common handset. Although this type designation was not used before ca. 1930, predecessor types were produced starting approximately in 1927 with the A handset mounting, and the B handset mounting in 1928. Earlier telephones by Western Electric had been of the candlestick type which featured a transmitter fixed to the base, and a receiver held by the user to the ear. The design of the A handset mounting was inherited from the candlestick desk stands, while the B-type was slightly reshaped. Although the B handset mounting was produced until 1932, Western Electric introduced a newly designed models, the D handset mounting in 1930, which had an oval foot print to improve physical stability during dialing.
Daniel Drawbaugh was a purported inventor of the telephone for which he sought a patent in 1880. His claims were contested by the Bell Telephone Company, which won a court decision in 1888.
Hilborne Lewis Roosevelt was a pioneering organ builder, telecommunication engineer, and a member of the Roosevelt family.
The candlestick telephone is a style of telephone that was common from the late 1890s to the 1940s. A candlestick telephone is also often referred to as a desk stand, an upright, or a stick phone. Candlestick telephones featured a mouth piece (transmitter) mounted at the top of the stand, and a receiver that was held by the user to the ear during a call. When the telephone was not in use, the receiver rested in the fork of the switch hook protruding to the side of the stand, thereby disconnecting the audio circuit from the telephone network.
Francis Blake, Jr. was an American inventor.
A telephone exchange, telephone switch, or central office is a telecommunications system used in the public switched telephone network (PSTN) or in large enterprises. It interconnects telephone subscriber lines or virtual circuits of digital systems to establish telephone calls between subscribers.
Thomas Augustus Watson was an assistant to Alexander Graham Bell, notably in the invention of the telephone in 1876.
