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A telephone handset
A telephone handset
A touch-tone telephone dial
A touch-tone telephone dial
Complex relay used in a telephone switching system.
Complex relay used in a telephone switching system.
This article is about telephone technology. For the game of telephone, see Telephone (game). For the band, see Téléphone.

The telephone or phone (Greek: tele = far away and phone = voice) is a telecommunications device which is used to transmit and receive sound (most commonly voice and speech) across distance. Most telephones operate through transmission of electric signals over a complex telephone network which allows almost any phone user to communicate with almost any other.

There are four principal means by which an end user using a telephone handset may connect to a telephone network: a traditional fixed phone "landline", which uses dedicated physical wire connections connected to a single location; wireless and radio telephones, which use either analog or digital radio signals; satellite telephones, which utilise telecommunications satellites; and voice over internet protocol (VOIP) telephones, which use broadband internet connections.

Between end users, transmissions across a network may be carried by fiber optic cable, point to point microwave or satellite relay.

Until relatively recently, a "telephone" generally referred only to landlines. Cordless and mobile phones are now common in many places around the world, with mobile phones expected to gradually displace the conventional landline telephone. Unlike a mobile phone, a cordless telephone is considered to be landline because it is only useable within a short distance of a small personal or domestic base station connected to a fixed phone line.

The identity of the inventor of the electric telephone remains in dispute. Antonio Meucci, Philip Reis, and Alexander Graham Bell, amongst others, have all been credited with the invention.



The very early history of the telephone is a confusing morass of claim and counterclaim, which was not clarified by the huge mass of lawsuits which hoped to resolve the patent claims of individuals. There was a lot of money involved, particularly in the Bell Telephone companies, and the aggressive defense of the Bell patents resulted in much confusion. Additionally, the earliest investigators preferred publication in the popular press and demonstrating to investors instead of scientific publication and demonstrating to fellow scientists.

It is important to note that there is probably no one "inventor of the telephone." The modern telephone is the result of work done by many hands, all worthy of recognition of their addition to the field.

See Timeline of the telephone for a chronological survey of the telephone's invention and development.

See Invention of the telephone for a discussion of each of the critical technologies and their inventors.

Early development

The following is a brief summery of the history of the invention of the telephone:

The Ericofon was a very futuristic handset when it was introduced in 1956.
The Ericofon was a very futuristic handset when it was introduced in 1956.

Later history

The history of additional inventions and improvements of the electrical telephone includes the carbon microphone (later replaced by the electret microphone now used in almost all telephone transmitters), the manual switchboard, the rotary dial, the automatic telephone exchange, the computerized telephone switch, Touch Tone® dialing (DTMF), and the digitization of sound using different coding techniques including pulse code modulation or PCM (which is also used for .WAV files and compact discs).

Newer systems include IP telephony, ISDN, DSL, cell phone (mobile) systems, digital cell phone systems, cordless telephones, and the third generation cell phone systems that promise to allow high-speed packet data transfer.

The industry divided into telephone equipment manufacturers and telephone network operators (telcos). Operating companies often hold a national monopoly. In the United States, the Bell System was vertically integrated. It fully or partially owned the telephone companies that provided service to about 80% of the telephones in the country and also owned Western Electric, which manufactured or purchased virtually all the equipment and supplies used by the local telephone companies. The Bell System divested itself of the local telephone companies in 1984 in order to settle an antitrust suit brought against it by the United States Department of Justice.

In 1926 Bell Laboratories and the British Post Office engineered the first two-way conversation across the Atlantic.

The first commercial transatlantic telephone call was between New York City and London and occurred on January 7, 1927.

Digital Telephony

Digital telephony emerged when end-to-end analog circuits were replaced by islands of digital circuits. Advances in digital transmission technology made it possible to carry multiple digital circuits on a single transmission medium Multiplexing. While the end instrument remained analog, the analog signals reaching the aggregation point Serving Area Interface SAI or the Central Office CO were converted to digital signals. Digital Loop Carriers DLC carried multiple analog telephone lines to the CO after converting them to digital signals, initially in fewer copper pairs and later on optical fiber. COs were interconnected by SONET carriers.


  • The modern handset came into existence when a Swedish lineman tied a microphone and earphone to a stick so he could keep a hand free.
  • The folding portable phone was an intentional copy of the fictional futuristic communicators (which in use actually more closely resembled walkie-talkies) used in the television show Star Trek.

Wireless technologies

Cordless telephones

Cordless handset
Cordless handset

Cordless telephones, first invented by Teri Pall in 1965, consist of a base unit that connects to the land-line system and also communicates with remote handsets by low power radio. This permits use of the handset from any location within range of the base. Because of the power required to transmit to the handset, the base station is powered with an electronic power supply. Thus, cordless phones typically do not function during power outages. Initially, cordless phones used the 1.7 MHz range to communicate between base and handset. Because of quality and range problems, these units were soon superseded by systems that used frequency modulation in higher frequency ranges (49 MHz, 900 MHz, 2.4 GHz, and 5.8 GHz). 2.4 GHz cordless phones can interfere with certain wireless LAN protocols (802.11b/g) due to the usage of the same frequencies. Due to crowding on the 2.4 GHz band, several "channels" are utilized in an attempt to guard against degradation in the quality of the voice signal. The range of modern cordless phones is normally on the order of a few hundred yards.

Wireless phone systems

While the term "wireless" means radio and can refer to any telephone that uses radio waves it is primarily used for cell phones. In the United States wireless companies tend to used the term wireless to refer to a wide range of services while the cell phone itself is called a mobile phone, mobile, cell phone or simply cell with the trend now moving towards mobile.

The changes in terminology is partially due to providers using different terms in marketing to differentiate newer digital services from older analog systmes and services of one company from another.

Cellular phone

Modern mobile phone systems are cell-structured. Radio is used to communicate between a handset and nearby cell-sites.

When a handset gets too far from a cell-site, a computer system commands the handset and a closer cell-site to take up the communications on a different channel without interrupting the call.

Radio frequencies are a limited, shared resource. The higher frequencies used by cell phones have advantages over short distances. Connection distance is somewhat predictable and can be contolled by adjusting the power level. By only using enough power to connect to the "nearest" cell site phones using one cell site will cause almost no interference with phones using the same frequencies on another cell site. The higher frequencies also work well with various forms of multiplexing which allows more than one phone to connect to the same tower with the same set of frequencies.

Cordless/mobile phones

There are phones that work as a cordless phone when near their corresponding base station (and sometimes other base stations) and work as a wireless phone when in other locations but for a variety of reasons did not become popular.

Some kinds of cordless phones work like cellular phones but only within a small private network covering a building or group of buildings. These kinds of systems using VoIP are poplular in hospitals and factories where the same wireless network can be used for both data and voice.

VoIP Telephony

A WiFi-based VoIP phone
A WiFi-based VoIP phone

Also known as Internet telephony or Voice over IP (VoIP), digital telephony is a disruptive technology that is rapidly replacing traditional telephone networks. In Japan and Korea up to 10% of subscribers, as of January 2005, have switch from analog to digital telephone service. A recent Newsweek article suggested that Internet telephony may be "the next big thing." [2]

Digital telephones use a broadband Internet connection to transmit conversations as data packets. In addition to replacing the PSTN, digital telephony is also competing with mobile phone networks by offering free or lower cost connections via WiFi hotspots. As mentioned above VoIP is also used on private wireless networks which may or may not have a connection to the outside telephone network.

Telephone equipment research labs

Bell Labs is a noted telephone equipment research laboratory, amongst its other research fields.

Telephone operating companies

In some countries, many telephone operating companies (commonly abbreviated to telco) are in competition to provide telephony services. Some of them include those in the following list. However, the list only includes providers of copper wires from the exchange to the user, not those who only supply "Voice over IP" or only transport voice signals between exchanges.

See also: List of telephone operating companies

See also

Look up telephone on Wiktionary, the free dictionary.

Telephone equipment

Telephone equipment manufacturers

Several manufacturers build telephones of all kinds. Some of these are:

Telephone technology

Telephone system, organization, and structure

Telephone hacking and exploitation

US-specific terminology

Telephone terminology

Telephone Standards

Wired Standards

Wireless Standards

There are many standards for common carrier wireless telephony, often with incompatible standards used in the same nation:


  • Huurdeman, Anton A. (2003). The Worldwide History of Telecommunications, IEEE Press and J. Wiley & Sons, 2003. ISBN 0471205052


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