The telephone (from the Greek Greek , an independent branch of the Indo-European family of languages, is the language of the Greeks. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. In its ancient form, it is the language of classical ancient Greek literature and the New Testament of: τῆλε, tēle, "far" and φωνή, phōnē, "voice"), often colloquially A colloquialism is a linguistic phrase that is characteristic of or only appropriate for casual, ordinary, familiar, and/or informal written or spoken conversation, rather than for formal speech, standard writing, or paralinguistics. Dictionaries often display colloquial words and phrases with the abbreviation colloq. as an identifier referred to as a phone, is a telecommunications Telecommunication is the transmission of messages, over significant distances, for the purpose of communication. In earlier times, telecommunications involved the use of visual signals, such as smoke, semaphore telegraphs, signal flags, and optical heliographs, or audio messages via coded drumbeats, lung-blown horns, or sent by loud whistles, for device that transmits A transmitter is an electronic device which, usually with the aid of an antenna, propagates an electromagnetic signal such as radio, television, or other telecommunications and receives sound Sound is a travelling wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations, most commonly the human voice The human voice consists of sound made by a human being using the vocal folds for talking, singing, laughing, crying, screaming, etc. Human voice is specifically that part of human sound production in which the vocal folds are the primary sound source. Generally speaking, the mechanism for generating the human voice can be subdivided into three. Telephones are a point-to-point Point-to-point is sometimes referred to as P2P or Pt2Pt.[citation needed] This usage of P2P is distinct from P2P referring to peer-to-peer file sharing networks communication system whose most basic function is to allow two people separated by large distances to talk to one another. It is one of the most common household appliances Small appliance refers to a class of home appliances that are portable or semi-portable or which are used on tabletops, countertops, or other platforms. Such items are contrasted with major appliances, which are typically fixtures that cannot be easily moved. All appliances are intended to perform, enable, or assist in performing a job or changing in the developed world The term developed country is used to describe countries that have a high level of development according to some criteria. Which criteria, and which countries are classified as being developed, is a contentious issue and is surrounded by fierce debate. Economic criteria have tended to dominate discussions. One such criterion is income per capita;, and has long been considered indispensable to business, industry and government. The word "telephone" has been adapted to many languages and is widely recognized around the world.

All telephones have a microphone A microphone is an acoustic-to-electric transducer or sensor that converts sound into an electrical signal. In 1876, Emile Berliner invented the first microphone used as a telephone voice transmitter. Microphones are used in many applications such as telephones, tape recorders, karaoke systems, hearing aids, motion picture production, live and to speak into, an earphone Headphones are a pair of small loudspeakers, or less commonly a single speaker, with a way of holding them close to a user's ears and a means of connecting them to a signal source such as an audio amplifier, radio or CD player. They are also known as stereophones, headsets or, colloquially cans. The in-ear versions are known as earphones or which reproduces the voice of the other person, a ringer which makes a sound to alert the owner when a call is coming in, and a keypad A telephone keypad is a keypad that appears on a “Touch Tone” telephone. It was standardised when the dual-tone multi-frequency system was introduced in the 1960s, and replaced the rotary dial (or in older phones a telephone dial The rotary dial is a device mounted on or in a telephone or switchboard that is designed to send interrupted electrical pulses, known as pulse dialing, corresponding to the number dialed. The early form of the rotary dial used lugs on a finger plate instead of holes. A patent was filed on August 20, 1896 by employees of Almon Strowger, namely, A) to enter the telephone number A telephone number or phone number is a sequence of digits used to call from one telephone line to another in a public switched telephone network. When telephone numbers were invented, they were short — as few as one, two or three digits — and were given verbally to a switchboard operator. As phone systems have grown and interconnected to of the telephone being called. The microphone and earphone are usually built into a handset On a telephone, the handset is a device the user holds to the ear to hear audio. Modern handsets typically contain a microphone as well, but in early telephones the microphone was mounted on the phone itself, which often was attached to a wall at a convenient height for talking. Handsets on such phones were called receivers, a term often applied which is held up to the face to talk. The keypad may be in the handset or in a separate part. A landline A landline was originally an overland telegraph wire, as opposed to an undersea cable. Currently, landline (or land phone or main line or fixed-line) refers to a telephone line which travels through a solid medium, either metal wire or optical fibre, as distinguished from a mobile cellular line, where transmission is via radio waves. Landlines telephone is connected by a wire to the telephone network, while a mobile phone A mobile phone is an electronic device used for full duplex two-way radio telecommunications over a cellular network of base stations known as cell sites. Mobile phones differ from cordless telephones, which only offer telephone service within limited range through a single base station attached to a fixed land line, for example within a home or or cell phone A mobile phone is an electronic device used for full duplex two-way radio telecommunications over a cellular network of base stations known as cell sites. Mobile phones differ from cordless telephones, which only offer telephone service within limited range through a single base station attached to a fixed land line, for example within a home or is portable and communicates with the telephone network by radio Radio is the transmission of signals by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space. Information is carried by systematically changing some property of the radiated waves, such as. A cordless telephone A cordless telephone or portable telephone is a telephone with a wireless handset that communicates via radio waves with a base station connected to a fixed telephone line, usually within a limited range of its base station . The base station is on the subscriber premises, and attaches to the telephone network the same way a corded telephone does has a portable handset which communicates by radio with a base station connected by wire to the telephone network, and can only be used within a limited range of the base station.

The microphone A microphone is an acoustic-to-electric transducer or sensor that converts sound into an electrical signal. In 1876, Emile Berliner invented the first microphone used as a telephone voice transmitter. Microphones are used in many applications such as telephones, tape recorders, karaoke systems, hearing aids, motion picture production, live and converts the sound waves Sound is a travelling wave which is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations to electrical signals In the fields of communications, signal processing, and in electrical engineering more generally, a signal is any time-varying or spatial-varying quantity, which are sent through the telephone network The public switched telephone network is the network of the world's public circuit-switched telephone networks. Originally a network of fixed-line analog telephone systems, the PSTN is now almost entirely digital in its core and includes mobile as well as fixed telephones to the other phone, where they are converted back to sound waves by the earphone Headphones are a pair of small loudspeakers, or less commonly a single speaker, with a way of holding them close to a user's ears and a means of connecting them to a signal source such as an audio amplifier, radio or CD player. They are also known as stereophones, headsets or, colloquially cans. The in-ear versions are known as earphones or in the other phone's handset. Telephones are a duplex A duplex communication system is a system composed of two connected parties or devices that can communicate with one another in both directions communications medium, meaning they allow the people on both ends to talk at once. The telephone network, consisting of a worldwide net of telephone lines A telephone line or telephone circuit is a single-user circuit on a telephone communications system. Typically this refers to the physical wire or other signaling medium connecting the user's telephone apparatus to the telecommunications network, and usually also implies a single telephone number for billing purposes reserved for that user, fiberoptic cables, microwave transmission Microwave transmission refers to the technology of transmitting information by the use of the radio waves whose wavelengths are conveniently measured in small numbers of centimeters, by using various electronic technologies. These are called microwaves. This part of the radio spectrum ranges across frequencies of roughly 1.0 gigahertz to 30 GHz, cellular networks A cellular network is a radio network made up of a number of cells, each served by at least one fixed-location transceiver known as a cell site or base station. When joined together these cells provide radio coverage over a wide geographic area. This enables a large number of portable transceivers to communicate with each other and with fixed, communications satellites A communications satellite is an artificial satellite stationed in space for the purpose of telecommunications. Modern communications satellites use a variety of orbits including geostationary orbits, Molniya orbits, other elliptical orbits and low (polar and non-polar) Earth orbits, and undersea telephone cables connected by switching centers A switching center is a node in a telecommunications Circuit switching network which is connected to either another switching center and/or to end user devices. Switching centers are aware of other centers and possible routes between them such that on demand a center can establish an optimal route for a demanded circuit. An optimal route may, allows any telephone in the world to communicate with any other. Each telephone line has an identifying number called its telephone number A telephone number or phone number is a sequence of digits used to call from one telephone line to another in a public switched telephone network. When telephone numbers were invented, they were short — as few as one, two or three digits — and were given verbally to a switchboard operator. As phone systems have grown and interconnected to. In order to initiate a telephone call A telephone call is a connection over a telephone network between the calling party and the called party, a conversation with another telephone, the user enters the other telephone's number into a numeric keypad A keypad is a set of buttons arranged in a block or "pad" which usually bear digits and other symbols and usually a complete set of alphabetical letters. If it mostly contains numbers then it can also be called a numeric keypad. Keypads are found on many alphanumeric keyboards and on other devices such as calculators, push-button on his/her phone. Graphic symbols used to designate telephone service or phone-related information in print, signage, and other media include ℡(U+ Unicode is a computing industry standard for the consistent representation and handling of text expressed in most of the world's writing systems. Developed in conjunction with the Universal Character Set standard and published in book form as The Unicode Standard, the latest version of Unicode consists of a repertoire of more than 107,0002121), ☎(U+ Unicode is a computing industry standard for the consistent representation and handling of text expressed in most of the world's writing systems. Developed in conjunction with the Universal Character Set standard and published in book form as The Unicode Standard, the latest version of Unicode consists of a repertoire of more than 107,000260E), ☏(U+ Unicode is a computing industry standard for the consistent representation and handling of text expressed in most of the world's writing systems. Developed in conjunction with the Universal Character Set standard and published in book form as The Unicode Standard, the latest version of Unicode consists of a repertoire of more than 107,000260F), and ✆(U+ Unicode is a computing industry standard for the consistent representation and handling of text expressed in most of the world's writing systems. Developed in conjunction with the Universal Character Set standard and published in book form as The Unicode Standard, the latest version of Unicode consists of a repertoire of more than 107,0002706).

History

Credit for the invention of the electric telephone is frequently disputed, and new controversies over the issue have arisen from time-to-time. As with other great inventions An invention is a new composition, device, or process. An invention may be derived from a pre-existing model or idea, or it could be independently conceived in which case it may be a radical breakthrough. In addition, there is cultural invention, which is an innovative set of useful social behaviors adopted by people and passed on to others such as radio, television, light bulb, and computer, there were several inventors who did pioneering experimental work on voice transmission over a wire and improved on each other's ideas. Innocenzo Manzetti Innocenzo Vincenzo Bartolomeo Luigi Carlo Manzetti was an Italian inventor born in Aosta. Following primary school he went to the Jesuit-run Saint Bénin Boarding School and then on to Turin where he was awarded a diploma in land surveying before returning to Aosta, Antonio Meucci Antonio Meucci was a compatriot of Italian revolutionary Giuseppe Garibaldi, and also an inventor, best known for developing a voice communication apparatus in 1857. Many credit him with the invention of the telephone; for example, the Enciclopedia Italiana di Scienze, Lettere ed Arti (Italian Encyclopedia of Science, Literature and Arts) calls, Johann Philipp Reis Johann Philipp Reis was a self-taught German scientist and inventor of Jewish ancestry, who in 1860-1861 constructed the first telephone, today called the Reis telephone. He is generally regarded as the true inventor of the telephone and was acknowledged as such by both Alexander Graham Bell (who admitted that he drew upon Reis's 1861 device in, Elisha Gray 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 and is considered by some writers to be the true inventor of the variable resistance telephone, despite losing out to Alexander Graham Bell for, Alexander Graham Bell Alexander Graham Bell was an eminent scientist, inventor, engineer and innovator who is credited with inventing the first practical telephone, and Thomas Edison Thomas Alva Edison was an American inventor, scientist, and businessman who developed many devices that greatly influenced life around the world, including the phonograph, the motion picture camera, and a long-lasting, practical electric light bulb. Dubbed "The Wizard of Menlo Park" (now Edison, New Jersey) by a newspaper reporter, he, among others, have all been credited with pioneering work on the telephone. An undisputed fact is that Alexander Graham Bell was the first to be awarded a patent Alexander Graham Bell was an eminent scientist, inventor, engineer and innovator who is credited with inventing the first practical telephone for the electric telephone by the United States Patent and Trademark Office (USPTO) in March 1876.^[2] That first patent by Bell was the master patent of the telephone, from which all other patents for electric telephone devices and features flowed.

The early history of the telephone became and still remains a confusing morass of claims and counterclaims, which were not clarified by the huge mass of lawsuits that hoped to resolve the patent claims of many individuals and commercial competitors. The Bell and Edison patents, however, were forensically victorious and commercially decisive.

A Hungarian engineer, Tivadar Puskás quickly invented the telephone switchboard in 1876, which allowed for the formation of telephone exchanges, and eventually networks. ^[3]

Basic principles

A traditional landline telephone system, also known as "plain old telephone service" (POTS), commonly handles both signaling and audio information on the same twisted pair of insulated wires: the telephone line. Although originally designed for voice communication, the system has been adapted for data communication such as Telex, Fax and dial-up Internet communication. The signaling equipment consists of a bell, beeper, light or other device to alert the user to incoming calls, and number buttons or a rotary dial to enter a telephone number for outgoing calls. A twisted pair line is preferred as it is more effective at rejecting electromagnetic interference (EMI) and crosstalk than an untwisted pair.

The telephone consists of an alerting device, usually a ringer, that remains connected to the phone line whenever the phone is "on hook", and other components which are connected when the phone is "off hook". These include a transmitter (microphone), a receiver (speaker) and other circuits for dialing, filtering, and amplification. A calling party wishing to speak to another party will pick up the telephone's handset, thus operating a button switch or "switchhook", which puts the telephone into an active (off hook) state by connecting the transmitter (microphone), receiver (speaker) and related audio components to the line. This circuitry has a low resistance (less than 300 ohms) which causes DC current from the telephone exchange to flow through the line. The exchange detects this current, attaches a digit receiver circuit to the line, and sends a dial tone to indicate readiness. On a modern push-button telephone, the calling party then presses the number buttons in a sequence corresponding to the telephone number of the called party. The buttons are connected to a tone generator circuit that produces DTMF tones which end up at a circuit at the exchange. A rotary dial telephone employs pulse dialing, sending electrical pulses corresponding to the telephone number to the exchange. (Most exchanges are still equipped to handle pulse dialing.) Provided the called party's line is not already active or "busy", the exchange sends an intermittent ringing signal (about 90 volts AC in North America and UK and 60 volts in Germany) to alert the called party to an incoming call. If the called party's line is active, the exchange sends a busy signal to the calling party. However, if the called party's line is active but has call waiting installed, the exchange sends an intermittent audible tone to the called party to indicate an incoming call.

The phone's ringer is connected to the line through a capacitor, a device which blocks the flow of DC current but permits AC current. This constitutes a mechanism whereby the phone draws no current when it is on hook, but exchange circuitry can send an AC voltage down the line to activate the ringer for an incoming call. When a landline phone is inactive or "on hook", the circuitry at the telephone exchange detects the absence of DC current flow and therefore "knows" that the phone is on hook with only the alerting device electrically connected to the line. When a party initiates a call to this line, and the ringing signal is transmitted. When the called party picks up the handset, they actuate a double-circuit switchhook which simultaneously disconnects the alerting device and connects the audio circuitry to the line. This, in turn, draws DC current through the line, confirming that the called phone is now active. The exchange circuitry turns off the ring signal, and both phones are now active and connected through the exchange. The parties may now converse as long as both phones remain off hook. When a party "hangs up", placing the handset back on the cradle or hook, DC current ceases to flow in that line, signaling the exchange to disconnect the call.

Calls to parties beyond the local exchange are carried over "trunk" lines which establish connections between exchanges. In modern telephone networks, fiber-optic cable and digital technology are often employed in such connections. Satellite technology may be used for communication over very long distances.

In most telephones, the transmitter and receiver (microphone and speaker) are located in the handset, although in a speakerphone these components may be located in the base or in a separate enclosure. Powered by the line, the transmitter produces an electric current whose voltage varies in response to the sound waves arriving at its diaphragm. The resulting current is transmitted along the telephone line to the local exchange then on to the other phone (via the local exchange or a larger network), where it passes through the coil of the receiver. The varying voltage in the coil produces a corresponding movement of the receiver's diaphragm, reproducing the sound waves present at the transmitter.

A Lineman's handset is a telephone designed for testing the telephone network, and may be attached directly to aerial lines and other infrastructure components.

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