How to Wire a Telephone Jack

  • 01 of 06

    Telephone Wiring Basics

    Young woman screwing phone jack into wall, side view
    Bruce Laurance/Digital Vision/Getty Images

    Old phone cable typically has four wires inside: red, green, black and yellow. If you're extending a line to a room or other part of the house, you can use this type of cable, or you can use Category 3 or 5 (Cat-3 or Cat-5) data cable, which also has multiple wires but with a different color scheme. Category cable works just as well as the old cable for phone service, and it works much better for data (such as for a DSL internet connection). The steps below show you how to install a new...MORE phone jack and make sense of the color combinations. 

    Note: Telephone wires inside your home carry a very low-voltage electrical current and are safe to work on without shutting off the power. In fact, only the phone company can shut off the power. But just to be safe, don't work on phone wiring with wet hands or when standing in water. 

    Supplies Needed:

    Continue to 2 of 6 below.
  • 02 of 06

    Strip the Outer Sheathing

    Strip 2 to 3 inches of the outer sheathing from the phone cable, using wire strippers. An old-style four-wire cable fits the 10-gauge slot on the wire strippers. Rotate the strippers as needed to cut all the way around the sheathing, being careful not to cut into the insulated wires inside the cable.

    Alternatively, some phone cables have a pull cord inside that strips the sheathing as you pull back on it. In this case, start by stripping only a small amount of the sheathing using wire strippers,...MORE then use the pull cord to cut back the sheathing 2 to 3 inches. Trim off the cut sheathing. 

    Continue to 3 of 6 below.
  • 03 of 06

    Untwist the Individual Cable Wires

    Untwist the individual cable wires from one another. Strip 1/2 to 3/4 inch of insulation from each wire that you need, using the 20- or 22-gauge slot on the wire strippers. In most cases, you need to strip only two of the wires, based on which phone line you are adding to: 

    Old Four-Wire Cable: 

    • Line 1 (primary phone line): red and green
    • Line 2 (secondary line): black and yellow

    Cat-3 or Cat-5 Cable: 

    • Line 1 (primary phone line): blue and white-with-blue-stripe 
    • Line 2 (secondary line): orange...MORE and white-with-orange-stripe
    Continue to 4 of 6 below.
  • 04 of 06

    Mounting the Plate

    Remove the cover from the front of the phone jack, exposing the mounting plate and mounting screw holes. Mount the plate to the wall, molding or other structure, using a drill-driver and small wood screws or drywall screws.  

    Continue to 5 of 6 below.
  • 05 of 06

    Connect the Wires

    Connect the stripped wires from the phone cable to the corresponding screw terminals on the jack, using the following color combinations; each jack terminal is identified by the color of the wire that is preattached to it:

    Old Four-Wire Cable: 

    • Line 1 (primary phone line): red wire to red terminal; green wire to green terminal
    • Line 2 (secondary line): black wire to black terminal; yellow wire to yellow terminal

    Cat-3 or Cat-5 Cable: 

    • Line 1 (primary phone line): blue wire to red terminal;...MORE white-with-blue-stripe wire to green terminal
    • Line 2 (secondary line): orange wire to yellow terminal; white-with-orange-stripe wire to black terminal 

    To make the wire connections, loosen each terminal screw with a screwdriver. Wrap the bare copper end of the wire around the screw with needlenose pliers. Tighten the screw to secure the wire. The wire insulation should stop just before the screw; none of the insulation should be under the screw. 

    Continue to 6 of 6 below.
  • 06 of 06

    Reinstall the Cover

    Reinstall the cover on to the jack's mounting place. Some covers are secured with a screw; others simply snap into place. Plug a phone into the jack to make sure the line is working properly.