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Telephone line
 
 
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A telephone line or telephone circuit (or just line or circuit within the industry
Industry

An industry is the manufacturing of a Good or Service within a category. Although industry is a broad term for any kind of economic production, in economics and urban planning industry is a synonym for the secondary sector, which is a type of economic activity involved in the manufacturing of raw materials into goods and products....
) is a single-user circuit
Telecommunication circuit

A telecommunication circuit is defined as follows:# The complete path between two terminals over which one-way or two-way communications may be provided....
 on a telephone
Telephone

The telephone is a telecommunications device that is used to transmitter and receive electronically or digitally encoded sound between two or more people conversing....
 communications
Telecommunication

Telecommunication is the assisted Transmission of Signal over a distance for the purpose of communication. In earlier times, this may have involved the use of smoke signals, Drum , Semaphore line, flag signals or heliograph....
 system. Typically this refers to the physical wire
Wire

A wire is a single, usually cylinder , elongated string of metal. Wires are used to bear mechanical Structural loads and to carry electricity and telecommunications Wiktionary:signal....
 or other signaling medium connecting the user's telephone apparatus to the telecommunications network, and usually also implies a single telephone number
Telephone number

A telephone number or phone number is a sequence of numbers used to call from one telephone line to another in a telephone network. When telephone numbers were invented, they were short - as few as two or three digits - and were used by people to call a few neighbors....
 for billing
Billing

Billing may mean:*The process of sending Accounts receivable to customers for goods or services is called billing. The document used is called an invoice....
 purposes reserved for that user.

In 1876 the earliest lines were single electrically conducting metal wires directly connecting one telephone to another with the Earth
Ground (electricity)

In electrical engineering, ground or earth may be the reference point in an electrical circuit from which other voltages are measured, or a common return path for electric current, or a direct physical connection to the Earth....
 forming the return circuit.






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A telephone line or telephone circuit (or just line or circuit within the industry
Industry

An industry is the manufacturing of a Good or Service within a category. Although industry is a broad term for any kind of economic production, in economics and urban planning industry is a synonym for the secondary sector, which is a type of economic activity involved in the manufacturing of raw materials into goods and products....
) is a single-user circuit
Telecommunication circuit

A telecommunication circuit is defined as follows:# The complete path between two terminals over which one-way or two-way communications may be provided....
 on a telephone
Telephone

The telephone is a telecommunications device that is used to transmitter and receive electronically or digitally encoded sound between two or more people conversing....
 communications
Telecommunication

Telecommunication is the assisted Transmission of Signal over a distance for the purpose of communication. In earlier times, this may have involved the use of smoke signals, Drum , Semaphore line, flag signals or heliograph....
 system. Typically this refers to the physical wire
Wire

A wire is a single, usually cylinder , elongated string of metal. Wires are used to bear mechanical Structural loads and to carry electricity and telecommunications Wiktionary:signal....
 or other signaling medium connecting the user's telephone apparatus to the telecommunications network, and usually also implies a single telephone number
Telephone number

A telephone number or phone number is a sequence of numbers used to call from one telephone line to another in a telephone network. When telephone numbers were invented, they were short - as few as two or three digits - and were used by people to call a few neighbors....
 for billing
Billing

Billing may mean:*The process of sending Accounts receivable to customers for goods or services is called billing. The document used is called an invoice....
 purposes reserved for that user.

In 1876 the earliest lines were single electrically conducting metal wires directly connecting one telephone to another with the Earth
Ground (electricity)

In electrical engineering, ground or earth may be the reference point in an electrical circuit from which other voltages are measured, or a common return path for electric current, or a direct physical connection to the Earth....
 forming the return circuit. Later in 1878 the Bell Telephone Company
Bell System

The Bell System refers to popular names used to described a group of companies that operated initial telephone services in the US. In 1877, the American Bell Telephone Company, named after Alexander Graham Bell, opened the first telephone exchange in New Haven, CT....
 began to use two-wire circuits (called the local loop
Local loop

In telephony, the local loop is the physical link or circuit that connects from the demarcation point of the Customer-premises equipment to the edge of the Common carrier or telecommunications service provider's network....
) from each user's telephone to end office
Telephone exchange

In the field of telecommunications, a telephone exchange or telephone switch is a system of electronic components that connects telephone calls....
s which performed any necessary electrical switching to allow voice signals to be transmitted to more distant telephones.

These wires were typically copper
Copper

Copper is a chemical element with the symbol Cu and atomic number 29.It is a ductile metal with very high thermal and electrical conductivity....
, although aluminium
Aluminium

Aluminium or aluminum is a silvery white and ductile member of the boron group of chemical elements. It has the symbol Al; its atomic number is 13....
 has also been used, and were carried in balanced pairs separated by about 25cm (10") on poles
Utility pole

A utility pole, alternately referred to as a power pole, telephone pole, telegraph pole or telegraph post, is a pole used to support overhead wire, cable, optical fiber, transformers, street lights and other overhead lighting, and related and unrelated equipment including signage....
 above the ground, and later as twisted pair
Twisted pair

Twisted pair cabling is a form of wiring in which two conductors are twisted together for the purposes of canceling out electromagnetic interference from external sources; for instance, electromagnetic radiation from unshielded twisted pair cables, and crosstalk between neighboring pairs....
 cables. Modern lines may run underground, and may carry analog or digital signals to the exchange, or may have a device that converts the analog signal
Analog signal

An analog or analogue signal is any continuous function Signal for which the time varying feature of the signal is a representation of some other time varying quantity, i.e analogous to another time varying signal....
 to digital for transmission on a carrier system
Carrier system

In telecommunication, a carrier system is a multichannel telecommunications system in which a number of individual channels are multiplexed for transmission ....
.

In most cases, two copper wires (tip and ring
Tip and ring

"Tip" and "Ring" are common terms in the telephone service industry referring to the two wires or sides of an ordinary telephone line. Tip is the ground_electricity side and Ring is the Battery_%28electricity%29 side of a phone circuit....
) for each telephone line run from a home or other small building to a local telephone exchange
Telephone exchange

In the field of telecommunications, a telephone exchange or telephone switch is a system of electronic components that connects telephone calls....
. There is a central junction box for the building where the wires that go to telephone jacks throughout the building and wires that go to the exchange meet and can be connected in different configurations depending upon the subscribed telephone service. The wires between the junction box and the exchange are known as the local loop
Local loop

In telephony, the local loop is the physical link or circuit that connects from the demarcation point of the Customer-premises equipment to the edge of the Common carrier or telecommunications service provider's network....
, and the network of wires going to an exchange, the access network
Access network

An access network is that part of a Telecommunication telecommunications network which connects subscribers to their immediate service provider....
.

Most houses in the U.S. are wired with 6-position modular jacks
Modular connector

Modular connector is the name given to a family of electrical connectors examples of which are pictured. These connectors were originally used in telephone wiring....
 with four conductors
Electrical conductor

In science and Electrical engineering, an electrical conductor is a material which contains movable electric charges. In metallic conductors, such as copper or aluminum, the movable charged particles are electrons ....
 wired to the house's junction box with copper wires. Those wires may be connected back to two telephone lines at the local telephone exchange
Telephone exchange

In the field of telecommunications, a telephone exchange or telephone switch is a system of electronic components that connects telephone calls....
, thus making those jacks RJ14
RJ11, RJ14, RJ25

RJ11 is a physical interface often used for terminating telephone wires.It is probably the most familiar of the registered jacks, being used for single line Plain old telephone service telephone jacks in most homes across the world....
 jacks. More often, only two of the wires are connected to the exchange as one telephone line, and the others are unconnected. In that case, the jacks in the house are RJ11
RJ11, RJ14, RJ25

RJ11 is a physical interface often used for terminating telephone wires.It is probably the most familiar of the registered jacks, being used for single line Plain old telephone service telephone jacks in most homes across the world....
.

Wiring information / pinouts

For information on wiring for the various telephone connectors, refer to telephone plug
Telephone plug

A telephone plug is a type of plug used to connect a telephone to the telephone wiring in a home or business, and in turn to a local loop network....
.

See also

  • Landline
    Landline

    A landline, main line or fixed-line is a telephone line which travels through a solid medium, either metal wire or optical fibre. This is distinguished from a mobile phone, where the medium used is the radio waves....
  • Party line
    Party line (telephony)

    In twentieth century telephone systems, a party line is an arrangement in which two or more customers are connected directly to the same local loop....
  • Local loop
    Local loop

    In telephony, the local loop is the physical link or circuit that connects from the demarcation point of the Customer-premises equipment to the edge of the Common carrier or telecommunications service provider's network....