{{Merge|telephone plug|date=February 2007}}

<!--this article is written based on the assumption that US practice is all that exists-->

[[Image:Telephone jack.jpg|thumb|A US telephone [[Registered jack]] with telephone cord plugged in]]

A '''telephone jack''' (or '''telephone socket''') is a [[telephone plug|jack]] located on a wall that is used to connect a [[telephone]] or [[computer]] to the [[telephone line]]. "Jack" is used in the USA, and "socket" in many other English speaking countries. Before phone jacks were invented, the cord from the telephone actually went into the wall and the telephone was not movable unless you had a telephone worker come move the telephone to another location.

The tools and equipment used to install telephone jacks are a pair of needle nose [[pliers]], a [[wire stripper]], a [[screwdriver]] (Phillips and flat) a small [[saw]] or sharp [[utility knife]], telephone wire, [[electrical tape]], a [[fish tape]] (which can be made of a coat hanger that has been straightened out), and a wall plate.

The wire that connects the telephone jack to the telephone line is hidden behind the wall or under the [[baseboard]]. Behind the baseboard is probably the easiest way to run the wire and it is run through the wall by using a hammer and finishing nails. In many cases, the cable is simply stapled to the wall surface.

It only takes two wires to connect a phone, but most house wiring contains four wires. In North America, the red and green wires are on the two center terminals of a normal phone jack, and the black and yellow wires are on the two outer terminals. This arrangement allows most houses to handle two phone lines very easily.

Many (if not most) line cords that people receive when they purchase a phone (to go between the wall jack and the phone) only have the two center wires. To save money, the outer two are omitted.

When a second phone line is brought into the house, this new line uses the yellow and black wires. If the house has a two-line phone, then the phone is normally ready to accept the second line automatically on the yellow and black wires. Only one line cord is plugged into the phone and it splits the two lines inside the phone.

A British socket is similar. However, for a single line it normally uses the two outer conductors of the four wire plug, rather than the two inner ones as in America.

A fax machine cannot be connected to the second phone line by just plugging it into the wall. A little plug-in converter is needed that takes the outer two terminals (yellow/black) of the phone jack and brings them to the center two terminals (red/green). The converter is plugged into the wall and the fax machine into the converter.

Some wall plates contain two phone jacks. These double phone jacks permit the connection of two phones or a phone/answering machine, phone/computer, or other combination. They may be wired for two telephone lines or they can share a single line.

[[Category:Telephony]]

[[Category:Telephone connectors]]

[[yi:טעלעפאון זשעק]]