Telephone line

A telephone line (or just line) is a single-user circuit on a telephone communications system. Typically this refers to the physical wire or other signalling medium connecting the user's telephone aparatus to the telecommunications network, and usually also implies a single telephone number for billing purposes reserved for that user.

Related Topics:
Telephone - Communications - Telecommunications

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In 1876 the earliest lines were single electrically conducting metal wires directly connecting one telephone to another with the Earth forming the return circuit. Later in 1878 the Bell Telephone Company ran lines (the local loop) from each user's telephone to end offices which performed any necessary electrical switching to allow voice signals to be transmitted to more distant telephones.

Related Topics:
1876 - 1878 - Bell Telephone Company - Local loop - End office

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These wires were typically copper, although aluminium has also been used, and were carried in pairs separated by about 25 cm on poles above the ground, and later as twisted pair cables. Modern lines may run underground to a device that converts the analogue signal to digital for transmission on optical fiber.

Related Topics:
Copper - Aluminium - Twisted pair - Analogue

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Most houses in the U.S. are wired with (4 conductor) RJ-11 copper wire that is capable of handling 2 telephone lines. Those conductors run to the local POP. When a local call is made, a switch connects that local loop to the local loop of the number that was dialed.

Related Topics:
RJ-11 - Switch - Local loop

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