- A telephone jack is really little more than a basic electrical circuit. Telephones work by converting sound into electrical signals (by way of a microphone) and sending them out to the telephone network (incoming electrical signals are converted back into sound by a small speaker in the telephone handset). While the telephone company network is somewhat more complex, basic telephone wiring serves only as a conduit for electrical signals to travel between the user's phone and the local central office. This task is accomplished by linking a plugged-in telephone to the telephone company network over two or four color-coded wires.
- To wire a phone jack, home or business owners need only a few basic items. First, the telephone jack itself is necessary; jacks are readily available from most hardware and electronics stores and should include all necessary mounting hardware. Basic two- or four-wire telephone wire is also necessary, and the length depends on how far the jack will be from the outside Network Interface Device (NID). Finally, basic tools like a screwdriver, wire cutters, wire strippers and a drill will help complete the installation job.
- The first step in wiring a telephone jack is to run the telephone wire between the intended installation spot and the Network Interface Device. If the wire must pass through floors or walls, it may be necessary to drill a hole through which the wire can pass. In a standard residential installation, the wire may pass from the jack location through the floor, along a basement or crawlspace path and outside to the NID (office wiring may take a slightly different path). It is not necessary to run the wiring as the first step, but doing so will make later installation steps considerably easier.
- At the location intended for the new phone jack, remove the jack from the manufacturer's packaging and open it by either removing the screw or unsnapping the plastic case. Inside the jack, four color-coded wires connect to terminals; in a standard configuration, the red and green wires power the first telephone line served by the jack while the black and yellow wires serve the second line (if a second line is active). Strip a small portion of insulation away from the wire ran in Section Three above, and connect the wire to the marked connection points inside the jack. Reassemble the jack, and mount it to the wall in the desired location (depending on the jack type, it may be secured to the wall using either screws or double-sided tape). A telephone can now be plugged in to the jack, but it will not get a dial tone until the other end of the wiring is connected to the NID.
- Outside the home or office, locate the telephone company NID. In most deployments, the NID is a small gray or beige box with telephone wires running into it; it may be secured in a closed position with snaps or a small screw. If the NID is closed with a screw, remove the screw and open the box; if it is closed using plastic snaps, simply apply firm (but not excessive) pressure to open. On the inside of the NID, the same color codes found in the telephone jack will be apparent; if the home or office only has one telephone line, though, the black and yellow wires may simply be hanging unconnected. To connect the wiring for the new jack, strip a small portion of insulation from the end of the red and green wires. Loosen the screw retaining the green wires slightly, insert the newly exposed portion of the green wire, and retighten the screw. Repeat this process for the red wire and, if necessary, the black and yellow wires. When all wires have been securely reconnected, close the NID and replace any removed hardware. The new telephone jack is now active and a connected telephone will play a dial tone when the receiver is lifted.
