![AT&T push button telephone western electric model 2500 dmg black](https://upload.wikimedia.org/wikipedia/commons/8/81/AT%26T_push_button_telephone_western_electric_model_2500_dmg_black.jpg)
A telephone is a
telecommunication
Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than that fe ...
s 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
In physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid.
In human physiology and psychology, sound is the ''reception'' of such waves and their ''perception'' by the ...
, typically and most efficiently the
human voice, into electronic
signal
In signal processing, a signal is a function that conveys information about a phenomenon. Any quantity that can vary over space or time can be used as a signal to share messages between observers. The '' IEEE Transactions on Signal Processing' ...
s that are transmitted via
cable
Cable may refer to:
Mechanical
* Nautical cable, an assembly of three or more ropes woven against the weave of the ropes, rendering it virtually waterproof
* Wire rope, a type of rope that consists of several strands of metal wire laid into a hel ...
s and other communication channels to another telephone which reproduces the sound to the receiving user. The term is derived from el, 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.
In 1876,
Alexander Graham Bell was the first to be granted a United States
patent
A patent is a type of intellectual property that gives its owner the legal right to exclude others from making, using, or selling an invention for a limited period of time in exchange for publishing an enabling disclosure of the invention."A p ...
for a device that produced clearly intelligible replication of the human voice at a second device. This instrument was further developed by many others, and became rapidly indispensable in
business
Business is the practice of making one's living or making money by producing or Trade, buying and selling Product (business), products (such as goods and Service (economics), services). It is also "any activity or enterprise entered into for pr ...
,
government
A government is the system or group of people governing an organized community, generally a state.
In the case of its broad associative definition, government normally consists of legislature, executive, and judiciary. Government is a ...
, and in
household
A household consists of two or more persons who live in the same dwelling. It may be of a single family or another type of person group. The household is the basic unit of analysis in many social, microeconomic and government models, and is im ...
s.
The essential elements of a telephone are a
microphone
A microphone, colloquially called a mic or mike (), is a transducer that converts sound into an electrical signal. Microphones are used in many applications such as telephones, hearing aids, public address systems for concert halls and public ...
(''transmitter'') to speak into and an
earphone
Headphones are a pair of small loudspeaker drivers worn on or around the head over a user's ears. They are electroacoustic transducers, which convert an electrical signal to a corresponding sound. Headphones let a single user listen to an au ...
(''receiver'') which reproduces the voice at a distant location. The receiver and transmitter are usually built into a
handset
A handset is a component of a telephone that a user holds to the ear and mouth to receive audio through the receiver and speak to the remote party using the built-in transmitter. In earlier telephones, the transmitter was mounted directly on ...
which is held up to the ear and mouth during conversation. The transmitter converts the
sound wave
In physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid.
In human physiology and psychology, sound is the ''reception'' of such waves and their ''perception'' by the ...
s 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
A loudspeaker (commonly referred to as a speaker or speaker driver) is an electroacoustic transducer that converts an electrical audio signal into a corresponding sound. A ''speaker system'', also often simply referred to as a "speaker" or " ...
. 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
A telephone number is a sequence of digits assigned to a landline telephone subscriber station connected to a telephone line or to a wireless electronic telephony device, such as a radio telephone or a mobile telephone, or to other devices f ...
, 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
The public switched telephone network (PSTN) provides Communications infrastructure, infrastructure and services for public Telecommunications, telecommunication. The PSTN is the aggregate of the world's circuit-switched telephone networks that ...
. 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 phone
A mobile phone, cellular phone, cell phone, cellphone, handphone, hand phone or pocket phone, sometimes shortened to simply mobile, cell, or just phone, is a portable telephone that can make and receive calls over a radio frequency link whil ...
s 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.
Convergence in communication services has provided a broad spectrum of capabilities in cell phones, including mobile computing, giving rise to the
smartphone
A smartphone is a portable computer device that combines mobile telephone and computing functions into one unit. They are distinguished from feature phones by their stronger hardware capabilities and extensive mobile operating systems, whic ...
, the dominant type of telephone in the world today.
Early history
![Alexander Graham Telephone in Newyork](https://upload.wikimedia.org/wikipedia/commons/1/16/Alexander_Graham_Telephone_in_Newyork.jpg)
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 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
megaphone
A megaphone, speaking-trumpet, bullhorn, blowhorn, or loudhailer is usually a portable or hand-held, cone-shaped acoustic horn used to amplify a person's voice or other sounds and direct it in a given direction. The sound is introduced int ...
s. A communication device for sailing vessels, called ''telephone'', was invented by Captain John Taylor in 1844. This instrument used four
air horn
An air horn is a pneumatic device designed to create an extremely loud noise for signaling purposes. It usually consists of a source which produces compressed air, which passes into a horn through a reed or diaphragm. The stream of air cause ...
s to communicate with vessels in foggy weather.
Johann Philipp Reis
Johann Philipp Reis (; 7 January 1834 – 14 January 1874) was a self-taught German scientist and inventor. In 1861, he constructed the first ''make-and-break'' telephone, today called the Reis telephone.
Early life and education
Reis ...
used the term in reference to his invention, commonly known as the
Reis telephone
The Reis telephone was an invention named after Philipp Reis of a telephone-like device he constructed. Reis's first successful work is dated to October 1861.
History
In 1861, Philipp Reis succeeded in creating a device that captured sound, co ...
, in c. 1860. His device appears to be the first device based on the conversion of sound into electrical impulses.
The term ''telephone'' was adopted into the vocabulary of many languages. It is derived from the el, τῆλε, ''tēle'', "far" and φωνή, ''phōnē'', "voice", together meaning "distant voice".
Credit for the invention of the electric telephone is frequently disputed. As with other influential
invention
An invention is a unique or novel device, method, composition, idea or process. An invention may be an improvement upon a machine, product, or process for increasing efficiency or lowering cost. It may also be an entirely new concept. If an i ...
s such as
radio
Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmit ...
,
television
Television, sometimes shortened to TV, is a telecommunication medium for transmitting moving images and sound. The term can refer to a television set, or the medium of television transmission. Television is a mass medium for advertisin ...
, the
light bulb, and the
computer
A computer is a machine that can be programmed to Execution (computing), carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital electronic computers can perform generic sets of operations known as C ...
, several inventors pioneered experimental work on ''voice transmission over a wire'' and improved on each other's ideas. New controversies over the issue still arise from time to time.
Charles Bourseul
Charles Bourseul (28 April 1829 – 23 November 1912) was a pioneer in development of the "make and break" telephone about 20 years before Bell made a practical telephone.
Bourseul was born in Brussels, Belgium, and grew up in Douai, France ...
,
Antonio Meucci
Antonio Santi Giuseppe Meucci ( , ; 13 April 1808 – 18 October 1889) was an Italian inventor and an associate of Giuseppe Garibaldi, a major political figure in the history of Italy. ,
Johann Philipp Reis
Johann Philipp Reis (; 7 January 1834 – 14 January 1874) was a self-taught German scientist and inventor. In 1861, he constructed the first ''make-and-break'' telephone, today called the Reis telephone.
Early life and education
Reis ...
,
Alexander Graham Bell, and
Elisha Gray, amongst others, have all been credited with the invention of the telephone.
Alexander Graham Bell was the first to be awarded a patent for the electric telephone by the
United States Patent and Trademark Office
The United States Patent and Trademark Office (USPTO) is an agency in the U.S. Department of Commerce that serves as the national patent office and trademark registration authority for the United States. The USPTO's headquarters are in Alexa ...
(USPTO) in March 1876.
Before Bell's patent, the telephone transmitted sound in a way that was similar to the telegraph. This method used vibrations and circuits to send electrical pulses, but was missing key features. Bell found that this method produced a sound through intermittent currents, but in order for the telephone to work a fluctuating current reproduced sounds the best. The fluctuating currents became the basis for the working telephone, creating Bell's patent. That first patent by Bell was the ''master patent'' of the telephone, from which other patents for electric telephone devices and features flowed.
In 1876, shortly after Bell's patent application, Hungarian engineer
Tivadar Puskás
Tivadar Puskás de Ditró (in older English technical literature: Theodore Puskás) (17 September 1844 – 16 March 1893) was a Hungarian inventor, telephone pioneer, and inventor of the telephone exchange. He was also the founder of Te ...
proposed the telephone switch, which allowed for the formation of
telephone exchange
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 syst ...
s, and eventually networks.
In the United Kingdom, ''the blower'' is used as a slang term for a telephone. The term came from navy slang for a
speaking tube
A speaking tube or voicepipe is a device based on two cones connected by an air pipe through which speech can be transmitted over an extended distance.
Use of pipes was suggested by Francis Bacon in the ''New Atlantis'' (1672). The usage for tel ...
. In the U.S., a somewhat dated slang term refers to the telephone as "the horn," as in "I couldn't get him on the horn," or "I'll be off the horn in a moment."
Timeline of early development
![Wall Hanging Telephone with Detachable Earpiece - Communication Gallery - BITM - Calcutta 2000 211](https://upload.wikimedia.org/wikipedia/commons/b/bf/Wall_Hanging_Telephone_with_Detachable_Earpiece_-_Communication_Gallery_-_BITM_-_Calcutta_2000_211.JPG)
* 1844:
Innocenzo Manzetti
Innocenzo Vincenzo Bartolomeo Luigi Carlo Manzetti (; 17 March 1826 – 15 March 1877) was an Italians, Italian inventor born in Aosta. Following his primary school studies he went to the Jesuit-run Saint Bénin Boarding School and then on to ...
first mooted the idea of a "speaking telegraph" or telephone. Use of the "speaking telegraph" and "sound telegraph" monikers would eventually be replaced by the newer, distinct name, "telephone".
* 26 August 1854:
Charles Bourseul
Charles Bourseul (28 April 1829 – 23 November 1912) was a pioneer in development of the "make and break" telephone about 20 years before Bell made a practical telephone.
Bourseul was born in Brussels, Belgium, and grew up in Douai, France ...
published an article in the magazine ''
L'Illustration
''L'Illustration'' was a weekly French language, French newspaper published in Paris from 1843 to 1944. It was founded by Édouard Charton with the first issue published on 4 March 1843, it became the first illustrated newspaper in France then, a ...
'' (Paris): "Transmission électrique de la parole" (electric transmission of speech), describing a "make-and-break" type telephone transmitter later created by Johann Reis.
* 26 October 1861:
Johann Philipp Reis
Johann Philipp Reis (; 7 January 1834 – 14 January 1874) was a self-taught German scientist and inventor. In 1861, he constructed the first ''make-and-break'' telephone, today called the Reis telephone.
Early life and education
Reis ...
(1834–1874) publicly demonstrated the
Reis telephone
The Reis telephone was an invention named after Philipp Reis of a telephone-like device he constructed. Reis's first successful work is dated to October 1861.
History
In 1861, Philipp Reis succeeded in creating a device that captured sound, co ...
before the Physical Society of Frankfurt.
[ Reis's telephone was not limited to musical sounds. Reis also used his telephone to transmit the phrase "Das Pferd frisst keinen Gurkensalat" ("The horse does not eat cucumber salad").
* 22 August 1865, ''La Feuille d'Aoste'' reported "It is rumored that English technicians to whom Manzetti illustrated his method for transmitting spoken words on the telegraph wire intend to apply said invention in England on several private telegraph lines". However, telephones would not be demonstrated there until 1876, with a set of telephones from Bell.
* 28 December 1871: ]Antonio Meucci
Antonio Santi Giuseppe Meucci ( , ; 13 April 1808 – 18 October 1889) was an Italian inventor and an associate of Giuseppe Garibaldi, a major political figure in the history of Italy. files patent caveat
A patent caveat, often shortened to caveat, was a legal document filed with the United States Patent Office. History
Caveats were instituted by the U.S. Patent Act of 1836, but were discontinued in 1909, with the U.S. Congress abolishing the sys ...
No. 3335 in the U.S. Patent Office, titled "Sound Telegraph", describing communication of voice between two people by wire. A patent caveat was not an invention patent
A patent is a type of intellectual property that gives its owner the legal right to exclude others from making, using, or selling an invention for a limited period of time in exchange for publishing an enabling disclosure of the invention."A p ...
award, but only an unverified notice filed by an individual that he or she intends to file a patent application in the future.
* 1874: Meucci, after having renewed the caveat for two years does not renew it again, and the caveat lapses.
* 6 April 1875: Bell's U.S. Patent 161,739 "Transmitters and Receivers for Electric Telegraphs" is granted. This uses multiple vibrating steel reeds in make-break circuits.
* 11 February 1876: Elisha Gray invents a liquid transmitter for use with the telephone but does not build one.
* 14 February 1876: Gray files a patent caveat
A patent caveat, often shortened to caveat, was a legal document filed with the United States Patent Office. History
Caveats were instituted by the U.S. Patent Act of 1836, but were discontinued in 1909, with the U.S. Congress abolishing the sys ...
for transmitting the human voice through a telegraphic circuit.
* 14 February 1876: Alexander Graham Bell applies for the patent "Improvements in Telegraphy", for electromagnetic telephones using what is now called amplitude modulation (oscillating current and voltage) but which he referred to as "undulating current".
* 19 February 1876: Gray is notified by the U.S. Patent Office of an interference between his caveat and Bell's patent application. Gray decides to abandon his caveat.
* 7 March 1876: Bell's U.S. patent 174,465 "Improvement in Telegraphy" is granted, covering "the method of, and apparatus for, transmitting vocal or other sounds telegraphically…by causing electrical undulations, similar in form to the vibrations of the air accompanying the said vocal or other sound."
* 10 March 1876: The first successful telephone transmission of clear speech using a liquid transmitter when Bell spoke into his device, "Mr. Watson, come here, I want to see you." and Watson heard each word distinctly.
* 30 January 1877: Bell's U.S. patent 186,787 is granted for an electromagnetic telephone using permanent magnets, iron diaphragms, and a call bell.
* 27 April 1877: Thomas Edison
Thomas Alva Edison (February 11, 1847October 18, 1931) was an American inventor and businessman. He developed many devices in fields such as electric power generation, mass communication, sound recording, and motion pictures. These inventio ...
files a patent application for a carbon (graphite) transmitter. It was published as No. 474,230 on 3 May 1892, after a 15-year delay because of litigation. Edison was granted patent 222,390 for a carbon granules transmitter in 1879.
Early commercial instruments
Early telephones were technically diverse. Some used a water microphone, some had a metal diaphragm that induced current in an electromagnet wound around a permanent magnet, and some were dynamic
Dynamics (from Greek δυναμικός ''dynamikos'' "powerful", from δύναμις ''dynamis'' "power") or dynamic may refer to:
Physics and engineering
* Dynamics (mechanics)
** Aerodynamics, the study of the motion of air
** Analytical dyna ...
– their diaphragm vibrated a coil of wire in the field of a permanent magnet or the coil vibrated the diaphragm. The sound-powered dynamic variants survived in small numbers through the 20th century in military and maritime applications, where its ability to create its own electrical power was crucial. Most, however, used the Edison/Berliner carbon transmitter
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 granul ...
, which was much louder than the other kinds, even though it required an induction coil which was an impedance matching
In electronics, impedance matching is the practice of designing or adjusting the input impedance or output impedance of an electrical device for a desired value. Often, the desired value is selected to maximize power transfer or minimize signal ...
transformer to make it compatible with the impedance of the line. The Edison patents kept the Bell monopoly viable into the 20th century, by which time the network was more important than the instrument.
Early telephones were locally powered, using either a dynamic transmitter or by the powering of a transmitter with a local battery. One of the jobs of outside plant
In telecommunication, the term outside plant has the following meanings:
*In civilian telecommunications, outside plant refers to all of the physical cabling and supporting infrastructure (such as conduit, cabinets, tower or poles), and any associ ...
personnel was to visit each telephone periodically to inspect the battery. During the 20th century, telephones powered from the telephone exchange over the same wires that carried the voice signals became common.
Early telephones used a single wire for the subscriber's line, with ground return used to complete the circuit (as used in telegraph
Telegraphy is the long-distance transmission of messages where the sender uses symbolic codes, known to the recipient, rather than a physical exchange of an object bearing the message. Thus flag semaphore is a method of telegraphy, whereas p ...
s). The earliest dynamic telephones also had only one port opening for sound, with the user alternately listening and speaking (or rather, shouting) into the same hole. Sometimes the instruments were operated in pairs at each end, making conversation more convenient but also more expensive.
At first, the benefits of a telephone exchange were not exploited. Instead, telephones were leased in pairs to a subscriber, who had to arrange for a telegraph contractor to construct a line between them, for example, between a home and a shop. Users who wanted the ability to speak to several different locations would need to obtain and set up three or four pairs of telephones. Western Union
The Western Union Company is an American multinational financial services company, headquartered in Denver, Colorado.
Founded in 1851 as the New York and Mississippi Valley Printing Telegraph Company in Rochester, New York, the company chang ...
, already using telegraph exchanges, quickly extended the principle to its telephones in New York City
New York, often called New York City or NYC, is the List of United States cities by population, most populous city in the United States. With a 2020 population of 8,804,190 distributed over , New York City is also the L ...
and San Francisco
San Francisco (; Spanish language, Spanish for "Francis of Assisi, Saint Francis"), officially the City and County of San Francisco, is the commercial, financial, and cultural center of Northern California. The city proper is the List of Ca ...
, and Bell was not slow in appreciating the potential.
Signalling
In signal processing, a signal is a function that conveys information about a phenomenon. Any quantity that can vary over space or time can be used as a signal to share messages between observers. The ''IEEE Transactions on Signal Processing'' ...
began in an appropriately primitive manner. The user alerted the other end, or the exchange operator, by whistling
Whistling without the use of an artificial whistle is achieved by creating a small opening with one's lips, usually after applying moisture (licking one's lips or placing water upon them) and then blowing or sucking air through the space. The a ...
into the transmitter. Exchange operation soon resulted in telephones being equipped with a bell in a ringer box
A ringer box is a telephone signaling device, similar to a bell box. It usually contains an electromechanical gong and was used with most early desk stand telephones, such as candlestick telephones and the Western Electric type Western Electric h ...
, first operated over a second wire, and later over the same wire, but with a condenser (capacitor
A capacitor is a device that stores electrical energy in an electric field by virtue of accumulating electric charges on two close surfaces insulated from each other. It is a passive electronic component with two terminals.
The effect of ...
) in series with the bell coil to allow the AC ringer signal through while still blocking DC (keeping the phone "on hook 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 th ...
"). Telephones connected to the earliest Strowger switch
The Strowger switch is the first commercially successful electromechanical stepping switch telephone exchange system. It was developed by the Strowger Automatic Telephone Exchange Company founded in 1891 by Almon Brown Strowger. Because of it ...
automatic exchanges had seven wires, one for the knife switch
A knife switch is a type of switch used to control the flow of electricity in a circuit. It is composed of a hinge which allows a metal lever, or knife, to be lifted from or inserted into a slot or jaw. The hinge and jaw are both fixed to an ...
, one for each telegraph key
A telegraph key is a specialized electrical switch used by a trained operator to transmit text messages in Morse code in a telegraphy system. Keys are used in all forms of electrical telegraph systems, including landline (also called wire) ...
, one for the bell, one for the push-button and two for speaking. Large wall telephones in the early 20th century usually incorporated the bell, and separate bell boxes for desk phones dwindled away in the middle of the century.
Rural and other telephones that were not on a common battery exchange had a magneto
A magneto is an electrical generator that uses permanent magnets to produce periodic pulses of alternating current. Unlike a dynamo, a magneto does not contain a commutator to produce direct current. It is categorized as a form of alternator, ...
hand-cranked generator to produce a high voltage alternating signal to ring the bells of other telephones on the line and to alert the operator. Some local farming communities that were not connected to the main networks set up barbed wire telephone lines that exploited the existing system of field fences to transmit the signal.
In the 1890s a new smaller style of telephone was introduced, packaged in three parts. The transmitter stood on a stand, known as a "candlestick
A candlestick is a device used to hold a candle in place. Candlesticks have a cup or a spike ("pricket") or both to keep the candle in place. Candlesticks are less frequently called "candleholders".
Before the proliferation of electricity, candl ...
" for its shape. When not in use, the receiver hung on a hook with a switch in it, known as a "switchhook". Previous telephones required the user to operate a separate switch to connect either the voice or the bell. With the new kind, the user was less likely to leave the phone "off the hook". In phones connected to magneto exchanges, the bell, induction coil, battery and magneto were in a separate bell box or "ringer box
A ringer box is a telephone signaling device, similar to a bell box. It usually contains an electromechanical gong and was used with most early desk stand telephones, such as candlestick telephones and the Western Electric type Western Electric h ...
". In phones connected to common battery exchanges, the ringer box was installed under a desk, or other out-of-the-way place, since it did not need a battery or magneto.
Cradle designs were also used at this time, having a handle with the receiver and transmitter attached, now called a handset
A handset is a component of a telephone that a user holds to the ear and mouth to receive audio through the receiver and speak to the remote party using the built-in transmitter. In earlier telephones, the transmitter was mounted directly on ...
, separate from the cradle base that housed the magneto crank and other parts. They were larger than the "candlestick" and more popular.
Disadvantages of single-wire operation such as crosstalk and hum from nearby AC power wires had already led to the use of twisted pairs and, for long-distance telephones, four-wire circuit
In telecommunication, a four-wire circuit is a two-way circuit using two paths so arranged that the respective signals are transmitted in one direction only by one path and in the other direction by the other path. The four-wire circuit gets its ...
s. Users at the beginning of the 20th century did not place long-distance call
In telecommunications, a long-distance call (U.S.) or trunk call (also known as a toll call in the U.K. ) is a telephone call made to a location outside a defined local calling area. Long-distance calls are typically charged a higher billing rate ...
s from their own telephones but made an appointment and were connected with the assistance of a telephone operator.
What turned out to be the most popular and longest-lasting physical style of telephone was introduced in the early 20th century, including Bell's 202-type desk set. A carbon granule transmitter and electromagnetic receiver were united in a single molded plastic handle, which when not in use was secured in a cradle in the base unit. The circuit diagram of the model 202 shows the direct connection of the transmitter to the line, while the receiver was inductively coupled. In local battery configurations, when the local loop was too long to provide sufficient current from the exchange, the transmitter was powered by a local battery and inductively coupled, while the receiver was included in the local loop. The coupling transformer and the ringer were mounted in a separate enclosure, called the subscriber set. The dial switch in the base interrupted the line current by repeatedly but very briefly disconnecting the line one to ten times for each digit, and the hook switch (in the center of the circuit diagram) disconnected the line and the transmitter battery while the handset was on the cradle.
In the 1930s, telephone sets were developed that combined the bell and induction coil with the desk set, obviating a separate ringer box. The rotary dial
A rotary dial is a component of a telephone or a telephone switchboard that implements a signaling technology in telecommunications known as pulse dialing. It is used when initiating a telephone call to transmit the destination telephone number ...
becoming commonplace in the 1930s in many areas enabled customer-dialed service, but some magneto systems remained even into the 1960s. After World War II, the telephone networks saw rapid expansion and more efficient telephone sets, such as the model 500 telephone
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 ...
in the United States, were developed that permitted larger local networks centered around central offices. A breakthrough new technology was the introduction of Touch-Tone signaling using push-button telephone
The push-button telephone is a telephone that has buttons or keys for dialing a telephone number, in contrast to having a rotary dial as in earlier telephone instruments.
Western Electric experimented as early as 1941 with methods of using mech ...
s by American Telephone & Telegraph Company
AT&T Corporation, originally the American Telephone and Telegraph Company, is the subsidiary of AT&T Inc. that provides voice, video, data, and Internet telecommunications and professional services to businesses, consumers, and government agen ...
(AT&T) in 1963.
File:Ericsson bakelittelefon 1931 sv.jpg, Ericsson DBH 1001 (ca. 1931), the first combined telephone made with a Bakelite housing and handset.
File:Minalinpampangajf2520 02.JPG, Telephone used by American soldiers (WWII, Minalin, Pampanga
Minalin, officially the Municipality of Minalin ( pam, Balen ning Minalin; fil, Bayan ng Minalin), is a 4th class municipality in the province of Pampanga, Philippines. According to the 2020 census, it has a population of 48,380 people.
Original ...
, Philippines
The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no),
* bik, Republika kan Filipinas
* ceb, Republika sa Pilipinas
* cbk, República de Filipinas
* hil, Republ ...
)
File:Oldphone.ogv, Video shows the operation of an Ericofon
The Ericofon is a one-piece plastic telephone created by the Ericsson Company of Sweden and marketed through the second half of the 20th century. It was the first commercially marketed telephone to incorporate the dial and handset into a singl ...
File:Sound-Powered Telephone Systems.jpg, Modern sound-powered emergency telephone
File:Motorola L71 on the China Mobile network 20100521.jpg, One type of mobile phone
A mobile phone, cellular phone, cell phone, cellphone, handphone, hand phone or pocket phone, sometimes shortened to simply mobile, cell, or just phone, is a portable telephone that can make and receive calls over a radio frequency link whil ...
, called a cell phone
Digital telephones and voice over IP
The invention of the transistor
upright=1.4, gate (G), body (B), source (S) and drain (D) terminals. The gate is separated from the body by an insulating layer (pink).
A transistor is a semiconductor device used to Electronic amplifier, amplify or electronic switch, switch e ...
in 1947 dramatically changed the technology used in telephone systems and in the long-distance transmission networks, over the next several decades. With the development of stored program control and MOS integrated circuit
upright=1.6, gate (G), body (B), source (S), and drain (D) terminals. The gate is separated from the body by an gate oxide">insulating layer (pink).
The metal–oxide–semiconductor field-effect transistor (MOSFET, MOS-FET, or MOS FET), also ...
s for electronic switching systems, and new transmission technologies such as pulse-code modulation
Pulse-code modulation (PCM) is a method used to digitally represent sampled analog signals. It is the standard form of digital audio in computers, compact discs, digital telephony and other digital audio applications. In a PCM Stream (comp ...
(PCM), telephony
Telephony ( ) is the field of technology involving the development, application, and deployment of telecommunication services for the purpose of electronic transmission of voice, fax, or data, between distant parties. The history of telephony is i ...
gradually evolved towards digital telephony
Telephony ( ) is the field of technology involving the development, application, and deployment of telecommunication services for the purpose of electronic transmission of voice, fax, or data, between distant parties. The history of telephony is i ...
, which improved the capacity, quality, and cost of the network.
Integrated Services Digital Network (ISDN) was launched in the 1980's, providing businesses and consumers with access to digital telephony services such as data, voice, video
Video is an electronic medium for the recording, copying, playback, broadcasting, and display of moving visual media. Video was first developed for mechanical television systems, which were quickly replaced by cathode-ray tube (CRT) syste ...
, and fax
Fax (short for facsimile), sometimes called telecopying or telefax (the latter short for telefacsimile), is the telephonic transmission of scanned printed material (both text and images), normally to a telephone number connected to a printer o ...
services.
The development of digital data communications methods made it possible to digitize voice and transmit it as real-time data across computer network
A computer network is a set of computers sharing resources located on or provided by network nodes. The computers use common communication protocols over digital interconnections to communicate with each other. These interconnections are ...
s and the Internet
The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a '' network of networks'' that consists of private, pub ...
, giving rise to the field of Internet Protocol (IP) telephony, also known as voice over Internet Protocol
Voice over Internet Protocol (VoIP), also called IP telephony, is a method and group of technologies for the delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks, such as the Internet. The terms Internet t ...
(VoIP). VoIP has proven to be a disruptive technology that is rapidly replacing traditional telephone network infrastructure.
By January 2005, up to 10% of telephone subscribers in Japan and South Korea
South Korea, officially the Republic of Korea (ROK), is a country in East Asia, constituting the southern part of the Korea, Korean Peninsula and sharing a Korean Demilitarized Zone, land border with North Korea. Its western border is formed ...
had switched to this digital telephone service. A January 2005 Newsweek
''Newsweek'' is an American weekly online news magazine co-owned 50 percent each by Dev Pragad, its president and CEO, and Johnathan Davis (businessman), Johnathan Davis, who has no operational role at ''Newsweek''. Founded as a weekly print m ...
article suggested that Internet telephony may be "the next big thing." The technology has spawned a new industry comprising many VoIP companies that offer services to consumer
A consumer is a person or a group who intends to order, or uses purchased goods, products, or services primarily for personal, social, family, household and similar needs, who is not directly related to entrepreneurial or business activities. T ...
s and business
Business is the practice of making one's living or making money by producing or Trade, buying and selling Product (business), products (such as goods and Service (economics), services). It is also "any activity or enterprise entered into for pr ...
es. The reported global VoIP market in October 2021 was $85.2 billion with a projection of $102.5 billion by 2026.
IP telephony uses high-bandwidth Internet connections and specialized customer premises equipment to transmit telephone calls via the Internet, or any modern private data network. The customer equipment may be an analog telephone adapter
An analog telephone adapter (ATA) is a device for connecting traditional analog telephones, fax machines, and similar customer-premises devices to a digital telephone system or a voice over IP telephony network.
An ATA is often built into a sma ...
(ATA) which translates the signals of a conventional analog telephone; an IP Phone
A VoIP phone or IP phone uses voice over IP technologies for placing and transmitting telephone calls over an IP network, such as the Internet. This is in contrast to a standard phone which uses the traditional public switched telephone network ...
, a dedicated standalone device; or a computer softphone
A softphone is a software program for making telephone calls over the Internet using a general purpose computer rather than dedicated hardware. The softphone can be installed on a piece of equipment such as a desktop, mobile device, or other comp ...
application, utilizing the microphone and headset devices of a personal computer or smartphone.
While traditional analog telephones are typically powered from the central office through the telephone line, digital telephones require a local power supply. Internet-based digital service also requires special provisions to provide the service location to the emergency services when an emergency telephone number
Most public switched telephone networks have a single emergency telephone number (sometimes known as the universal emergency telephone number or the emergency services number) that allows a caller to contact local emergency services for assis ...
is called.
Cordless telephones
A cordless telephone
A cordless telephone or portable telephone has a portable telephone handset that connects by radio to a base station connected to the public telephone network. The operational range is limited, usually to the same building or within some short ...
or portable telephone consists of a base station unit and one or more portable cordless handset
A handset is a component of a telephone that a user holds to the ear and mouth to receive audio through the receiver and speak to the remote party using the built-in transmitter. In earlier telephones, the transmitter was mounted directly on ...
s. The base station connects to a telephone line, or provides service by voice over IP (VOIP). The handset communicates with the base station via radio frequency
Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around to around . This is roughly between the upp ...
signals. A handset's operational range is limited, usually to within the same building or within a short distance from the base station.
Base station
Base stations include a radio transceiver which enables full-duplex, outgoing and incoming signals and speech with the handsets. The base station often includes a microphone, audio amplifier, and a loudspeaker to enable hands-free speakerphone
A speakerphone is a telephone with a microphone and loudspeaker provided separately from those in the handset. This device allows multiple persons to participate in a conversation. The loudspeaker broadcasts the voice or voices of those on the ot ...
conversations, without needing to use a handset. The base station may also have a numeric keypad for dialing, and a display for caller ID
Caller identification (Caller ID) is a telephone service, available in analog and digital telephone systems, including voice over IP (VoIP), that transmits a caller's telephone number to the called party's telephone equipment when the call i ...
. In addition, answering machine function may be built in.
The cordless handset contains a rechargeable battery, which the base station recharges when the handset rests in its cradle. Muilt-handset systems generally also have additional charging stands. A cordless telephone typically requires a constant electricity supply
Mains electricity or utility power, power grid, domestic power, and wall power, or in some parts of Canada as hydro, is a general-purpose alternating-current (AC) electric power supply. It is the form of electrical power that is delivered to h ...
to power the base station and charger units by means of a DC transformer which plugs into a wall AC power outlet.
Mobile phones
A typical SIM card (mini-SIM with a cutout to convert the card to micro-SIM size)
A mobile phone
A mobile phone, cellular phone, cell phone, cellphone, handphone, hand phone or pocket phone, sometimes shortened to simply mobile, cell, or just phone, is a portable telephone that can make and receive calls over a radio frequency link whil ...
or cellphone or hand phone is a handheld telephone which connects via radio transmissions to a cellular telephone network. The cellular network consists of a network of ground based transmitter/receiver stations with antennas – which are usually located on towers or on buildings – and infrastructure connecting to land-based telephone lines. Analog cellular networks first appeared in 1979, with the first digital cellular networks appearing in the early 1990s.
Mobile phones require a SIM card
A typical SIM card (mini-SIM with micro-SIM cutout)
A GSM mobile phone
file:Simkarte NFC SecureElement.jpg, T-Mobile nano-SIM card with NFC capabilities in the SIM tray of an iPhone 6s
file:Tf sim both sides.png, A TracFone Wireless SIM card ha ...
to be inserted into the phone. The SIM card is a small PVC card containing a small integrated circuit
An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuits on one small flat piece (or "chip") of semiconductor material, usually silicon. Large numbers of tiny ...
which stores the user's international mobile subscriber identity
The international mobile subscriber identity (IMSI) is a number that uniquely identifies every user of a cellular network. It is stored as a field and is sent by the mobile device to the network. It is also used for acquiring other details of th ...
(IMSI) number and its related key, which are used to identify and authenticate subscribers to the cellular network.
Mobile phones generally incorporate an LCD or OLED
An organic light-emitting diode (OLED or organic LED), also known as organic electroluminescent (organic EL) diode, is a light-emitting diode (LED) in which the emissive electroluminescent layer is a film of organic compound that emits light i ...
display, with some types, such as smartphones, having touch screens. Since the 1990s, mobile phones have gained other features which are not directly related to their primary function as telephones. These include text messaging, calendars, alarm clocks, personal schedulers, cameras, music players, games and later, internet access and smartphone
A smartphone is a portable computer device that combines mobile telephone and computing functions into one unit. They are distinguished from feature phones by their stronger hardware capabilities and extensive mobile operating systems, whic ...
functionality. Nearly all mobile phones have the ability to send text messages to other users via the SMS
Short Message/Messaging Service, commonly abbreviated as SMS, is a text messaging service component of most telephone, Internet and mobile device systems. It uses standardized communication protocols that let mobile devices exchange short text ...
(Short Message Service) protocol. The multimedia messaging service (MMS) protocol enables users to send and receive multimedia content, such as photos, audio files and video files. As their functionality has increased over the years, many types of mobile phone, notably smartphones, require an operating system
An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs.
Time-sharing operating systems schedule tasks for efficient use of the system and may also in ...
to run. Popular mobile phone operating systems in the past have included Symbian
Symbian is a discontinued mobile operating system
A mobile operating system is an operating system for mobile phones, tablets, smartwatches, smartglasses, or other non-laptop personal mobile computing devices. While computers such as typic ...
, Palm OS
Palm OS (also known as Garnet OS) was a mobile operating system initially developed by Palm, Inc., for personal digital assistants (PDAs) in 1996. Palm OS was designed for ease of use with a touchscreen-based graphical user interface. It is pro ...
, BlackBerry OS
BlackBerry OS is a discontinued proprietary mobile operating system developed by Canadian company BlackBerry Limited for its BlackBerry line of smartphone handheld devices. The operating system provides multitasking and supports specialized i ...
and mobile phone versions of Windows. As of 2022, the most used operating systems are Google's Android and Apple's iOS
iOS (formerly iPhone OS) is a mobile operating system created and developed by Apple Inc. exclusively for its hardware. It is the operating system that powers many of the company's mobile devices, including the iPhone; the term also include ...
.
Before the era of smartphones, mobile phones were generally manufactured by companies specializing in telecommunications equipment, such as Nokia
Nokia Corporation (natively Nokia Oyj, referred to as Nokia) is a Finnish multinational corporation, multinational telecommunications industry, telecommunications, technology company, information technology, and consumer electronics corporatio ...
, Motorola
Motorola, Inc. () was an American multinational telecommunications company based in Schaumburg, Illinois, United States. After having lost $4.3 billion from 2007 to 2009, the company split into two independent public companies, Motorol ...
, and Ericsson
(lit. "Telephone Stock Company of LM Ericsson"), commonly known as Ericsson, is a Swedish multinational networking and telecommunications company headquartered in Stockholm. The company sells infrastructure, software, and services in informa ...
. Since the advent of smartphones, mobile phone manufacturers have also included consumer electronics companies, such as Apple
An apple is an edible fruit produced by an apple tree (''Malus domestica''). Apple fruit tree, trees are agriculture, cultivated worldwide and are the most widely grown species in the genus ''Malus''. The tree originated in Central Asia, wh ...
, Samsung
The Samsung Group (or simply Samsung) ( ko, 삼성 ) is a South Korean multinational manufacturing conglomerate headquartered in Samsung Town, Seoul, South Korea. It comprises numerous affiliated businesses, most of them united under the ...
and Xiaomi
Corporation (; ), commonly known as Xiaomi and registered as Xiaomi Inc., is a Chinese designer and manufacturer of consumer electronics and related software, home appliances, and household items. Behind Samsung, it is the second largest ma ...
.
Smartphones
As of 2022, most mobile phones are smartphones, being a combination of a mobile phone and a personal computing device in the same unit. Most smartphones are primarily operated using a graphical user interface
The GUI ( "UI" by itself is still usually pronounced . or ), graphical user interface, is a form of user interface that allows users to interact with electronic devices through graphical icons and audio indicator such as primary notation, inste ...
and a touch screen. Many phones have a secondary voice user interface, such as Siri
Siri ( ) is a virtual assistant that is part of Apple Inc.'s iOS, iPadOS, watchOS, macOS, tvOS, and audioOS operating systems. It uses voice queries, gesture based control, focus-tracking and a natural-language user interface to answer qu ...
on Apple iPhones, which can operate many of the device's functions, as well as enabling users to use spoken commands to interact with the internet. Typically alphanumeric text input is accomplished via an on-screen virtual keyboard, although some smartphones have a small physical keyboard. Smartphones offer the ability to access internet data through the cellular network and via wi-fi, and usually allow direct connectivity to other devices via Bluetooth
Bluetooth is a short-range wireless technology standard that is used for exchanging data between fixed and mobile devices over short distances and building personal area networks (PANs). In the most widely used mode, transmission power is limi ...
or a wired interface, such as USB
Universal Serial Bus (USB) is an industry standard that establishes specifications for cables, connectors and protocols for connection, communication and power supply (interfacing) between computers, peripherals and other computers. A broad ...
or Lightning
Lightning is a naturally occurring electrostatic discharge during which two electric charge, electrically charged regions, both in the atmosphere or with one on the land, ground, temporarily neutralize themselves, causing the instantaneous ...
connectors. Smartphones, being able to run apps, have vastly expanded functionality compared to previous mobile phones. Having internet access and built in cameras, smartphones have made video calling
Videotelephony, also known as videoconferencing and video teleconferencing, is the two-way or multipoint reception and transmission of audio and video signals by people in different locations for real time communication.McGraw-Hill Concise Ency ...
readily accessible via IP connections. Smartphones also have access to a large number of web services and web apps, giving them functionality similar to traditional computers, although smartphones are often limited by their relatively small screen size and the size of their keyboards. Typically, smartphones feature such tools as cameras, media players, web browsers, email clients, interactive maps, satellite navigation and a variety of sensors, such as a compass
A compass is a device that shows the cardinal directions used for navigation and geographic orientation. It commonly consists of a magnetized needle or other element, such as a compass card or compass rose, which can pivot to align itself with ...
, accelerometers
An accelerometer is a tool that measures proper acceleration. Proper acceleration is the acceleration (the rate of change of velocity) of a body in its own instantaneous rest frame; this is different from coordinate acceleration, which is acce ...
and GPS receivers
A satellite navigation device (satnav device) is a user equipment that uses one or more of several global navigation satellite systems (GNSS) to calculate the device's geographical position and provide navigational advice.
Depending on the ...
. In addition to voice calls, smartphone users commonly communicate using a wide variety of messaging formats, including SMS, MMS, email, and various proprietary messaging services, such as iMessage
iMessage is an instant messaging service developed by Apple Inc. and launched in 2011. iMessage functions exclusively on Apple platforms: macOS, iOS, iPadOS, and watchOS.
Core features of iMessage, available on all supported platforms, in ...
and various social media platforms.
Mobile phone usage
In 2002, only 10% of the world's population used mobile phone
A mobile phone, cellular phone, cell phone, cellphone, handphone, hand phone or pocket phone, sometimes shortened to simply mobile, cell, or just phone, is a portable telephone that can make and receive calls over a radio frequency link whil ...
s and by 2005 that percentage had risen to 46%. By the end of 2009, there were a total of nearly 6 billion mobile and fixed-line telephone subscribers worldwide. This included 1.26 billion fixed-line subscribers and 4.6 billion mobile subscribers.Next-Generation Networks Set to Transform Communications
International Telecommunication Union website, 4 September 2007. Retrieved 5 July 2009.
See also
*
Bell System
The Bell System was a system of telecommunication companies, led by the Bell Telephone Company and later by the American Telephone and Telegraph Company (AT&T), that dominated the telephone services industry in North America for over one hundr ...
*
Bell Telephone Memorial
The Bell Memorial (also known as the Bell Monument or Telephone Monument) is a memorial designed by Walter Seymour Allward to commemorate the invention of the telephone by Alexander Graham Bell at the Bell Homestead National Historic Site, in Bra ...
*
Cellular network
A cellular network or mobile network is a communication network where the link to and from end nodes is wireless. The network is distributed over land areas called "cells", each served by at least one fixed-location transceiver (typically thre ...
*
Cordless telephone
A cordless telephone or portable telephone has a portable telephone handset that connects by radio to a base station connected to the public telephone network. The operational range is limited, usually to the same building or within some short ...
*
Harvard sentences
*
Index of telephone-related articles {{wiktionarypar, telephone
These are some of the links to articles that are telephone related.
See Telephony for many more links
0-9
* Harmonised service of social value, 116 telephone number
* Toll-free telephone number, 800 number
A-F
* Alexand ...
*
Jipp curve Jipp curve is a term for a graph plotting the number (density) of telephones against wealth as measured by the Gross Domestic Product (GDP) per capita. The Jipp curve shows across countries that teledensity increases with an increase in wealth or ec ...
*
List of telephone operating companies
This list identifies the fixed line operators and the mobile operators for the top 200 most populous countries in the world.
The list of countries and their populations is from List of countries by population. The CIA World Factbook is cited ...
*
Mobile operating system
A mobile operating system is an operating system for mobile phones, tablets, smartwatches, smartglasses, or other non-laptop personal mobile computing devices. While computers such as typical laptops are "mobile", the operating systems used on ...
*
Multimedia messaging service (MMS)
*
Party line (telephony)
A party line (multiparty line, shared service line, party wire) is a local loop telephone circuit that is shared by multiple telephone service subscribers.
Party line systems were widely used to provide telephone service, starting with the fir ...
*
Phone hacking
Phone hacking is the practice of exploring a mobile device often using computer exploits to analyze everything from the lowest memory and central processing unit levels up to the highest file system and process levels. Modern open source toolin ...
*
Radiotelephone
A radiotelephone (or radiophone), abbreviated RT, is a radio communication system for conducting a conversation; radiotelephony means telephony by radio. It is in contrast to '' radiotelegraphy'', which is radio transmission of telegrams (mes ...
*
Satellite phone
*
SIM card
A typical SIM card (mini-SIM with micro-SIM cutout)
A GSM mobile phone
file:Simkarte NFC SecureElement.jpg, T-Mobile nano-SIM card with NFC capabilities in the SIM tray of an iPhone 6s
file:Tf sim both sides.png, A TracFone Wireless SIM card ha ...
*
Spamming
Spamming is the use of messaging systems to send multiple unsolicited messages (spam) to large numbers of recipients for the purpose of commercial advertising, for the purpose of non-commercial proselytizing, for any prohibited purpose (especia ...
*
Telephone keypad
A telephone keypad is a keypad installed on a push-button telephone or similar telecommunication device for dialing a telephone number. It was standardized when the dual-tone multi-frequency signaling (DTMF) system was developed in the Bell Syst ...
*
Telephone jack and plug
A telephone jack and a telephone plug are electrical connectors for connecting a telephone set or other telecommunications apparatus to the telephone wiring inside a building, establishing a connection to a telephone network. The plug is inserted ...
*
Telephone tapping
Telephone tapping (also wire tapping or wiretapping in American English) is the monitoring of telephone and Internet-based conversations by a third party, often by covert means. The wire tap received its name because, historically, the monitorin ...
*
Tip and ring
Tip and ring are the two conductors or sides of a telephone line. Their names are derived from the telephone plugs used for connecting telephone calls in manual switchboards. One side of the line is connected to the metal ''tip'' of the plug, and ...
*
Videophone
Videotelephony, also known as videoconferencing and video teleconferencing, is the two-way or multipoint reception and transmission of audio and video signals by people in different locations for real time communication.McGraw-Hill Concise Ency ...
References
Further reading
* Brooks, John (1976). ''Telephone: The first hundred years''. HarperCollins.
*
* Casson, Herbert Newton. (1910) ''The history of the telephone'
online
* Coe, Lewis (1995). ''The Telephone and Its Several Inventors: A History.'' Jefferson, NC: McFarland & Co.
* Evenson, A. Edward (2000). ''The Telephone Patent Conspiracy of 1876: The Elisha Gray – Alexander Bell Controversy.'' Jefferson, NC: McFarland & Co.
* Fischer, Claude S. (1994) ''America calling: A social history of the telephone to 1940'' (Univ of California Press, 1994)
* Huurdeman, Anton A. (2003). ''The Worldwide History of Telecommunications'' Hoboken: NJ: Wiley-IEEE Press.
*
John, Richard R. (2010). ''Network Nation: Inventing American Telecommunications.'' Cambridge, MA: Harvard University Press.
* MacDougall, Robert. ''The People's Network: The Political Economy of the Telephone in the Gilded Age.'' Philadelphia: University of Pennsylvania Press.
* Mueller, Milton. (1993) "Universal service in telephone history: A reconstruction." ''Telecommunications Policy'' 17.5 (1993): 352–69.
* Todd, Kenneth P. (1998)
''A Capsule History of the Bell System'' American Telephone & Telegraph Company (AT&T).
External links
*
*
Virtual museum of early telephones*
*
*
*
*
* —''Telegraphy'' (Bell's first telephone patent)—Alexander Graham Bell
US 186,787''Electric Telegraphy'' (permanent magnet receiver)—Alexander Graham Bell
US 474,230''Speaking Telegraph'' (graphite transmitter)—Thomas Edison
US 203,016''Speaking Telephone'' (carbon button transmitter)—Thomas Edison
US 222,390''Carbon Telephone'' (carbon granules transmitter)—Thomas Edison
US 485,311''Telephone'' (solid back carbon transmitter)—Anthony C. White (Bell engineer) This design was used until 1925 and installed phones were used until the 1940s.
US 3,449,750''Duplex Radio Communication and Signalling Apparatus''—G. H. Sweigert
US 3,663,762''Cellular Mobile Communication System''—Amos Edward Joel (Bell Labs)
US 3,906,166''Radio Telephone System'' (DynaTAC
cell phone)—Martin Cooper et al. (Motorola)
{{Authority control
1876 introductions
American inventions
Canadian inventions
Discovery and invention controversies
German inventions
Scottish inventions
Office equipment
Telecommunications equipment
Articles containing video clips
Home appliances
19th-century inventions