How to Wire a Telephone

Every home has a phone box, also known as a Network Interface Device, regardless of whether or not the home has an active land line. Simply having this box, however, does not mean that there is working phone service inside the house. It is necessary to run telephone wire from the house to this box in order to have a working phone line. It is completely legal and cost effective to wire a telephone line yourself. There is no permit or inspection required, as the phone wiring that runs from the box to the house is your property. You can save a great deal of money by wiring a telephone yourself instead of hiring the phone company or an electrician to do it for you.


  1. Image titled Wire a Telephone Step 1
    Locate the Network Interface Device box on the outside of your house. This is a gray or tan box that measures roughly 8 by 12 inches. The Network Interface Device box is where the telephone wire from the phone company terminates, and also where the phone wiring going into the house will connect to the phone company line.
  2. Image titled Wire a Telephone Step 2
    Open the compartment labeled "customer access." You will notice modular plugs, as well as a pair of screw posts. The plugs look just like the phone jack that you plug your phone into inside of your house. There will be a line plugged into each modular plug for each phone company line that runs to your house. The pair of screw posts will contain one red screw and one green screw. These posts are where your new wiring will connect with the phone company wiring.
    • Before you begin your wiring project, unplug the phone company line that is plugged into the jack inside the box. This is just a safety precaution, as it will disconnect the (very low voltage) power flowing from the phone company line. You'll need to plug it back in once you've completed the wiring.
    • The red and green screws correspond to the wire colors that you will be connecting to the box.
  3. Image titled Wire a Telephone Step 3
    Purchase standard residential telephone cable at any hardware store. Use only round telephone cable.
    • Using wire cutters or scissors, gently cut the outer covering of the cable to expose 2 pairs of color-coded, insulated wire. One pair will be red and green (this pair is for line 1), and the other pair will be yellow and black (these wires can be used for line 2 in the future). Expose about 12 inch (1.3 cm) of bare wire.
  4. Image titled Wire a Telephone Step 4
    Open the house phone jack you are going to use to connect the new phone line. A straight-slot screwdriver will work. Wiring inside the jack will now be exposed.
    • Inside the jack you will find 4 colored wires: red, green, yellow, and black. Each wire is attached to a screw. Using a Phillips screwdriver, loosen each of the screws slightly so that you can pull the attached wire away.
    • Gently remove about 12 inch (1.3 cm) of covering from each of these wires, just as you did with the cable wires. Splice the cable wires to their matching jack wires by twisting them together. Wrap the spliced bare wires around the appropriate screws, and then tighten the screws.
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    Look at the layout of your home and decide the best way to run the new cable to the outside box.
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    Drill a hole in the outside wall where the cable will be exiting the house through the wall.
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    Push the phone cable back through the walls from the jack to the hole you've just drilled, then pull the cable out through the hole. Run the cable alongside the house to the Network Interface Device box.
    • Anchor the cable to the outside wall of the house every 6 to 10 inches (15.2 to 25.4 cm) by using a staple gun that shoots arched staples for phone cable. Or, you can use plastic cable straps secured with a tack hammer. Keep the cable away from anything damp or sharp.
  8. Image titled Wire a Telephone Step 8
    Punch a hole in the thin circle at the bottom of the box lid. This thin plastic can be punched through with a pen or pencil.
    • Pull the wire up through the hole, and run it behind the hinge pin on the left side of the box door to keep it in place. Pull it from behind the hinge so that it can be connected to the red and green screw posts. Loosen the screw posts one full turn.
  9. Image titled Wire a Telephone Step 9
    Strip off 12 inch (1.3 cm) of insulation covering from each wire.
  10. Image titled Wire a Telephone Step 10
    Wrap each wire in a clockwise direction around the post between the washers and the screw, connecting the red wire to the red screw post and the green wire to the green screw post. Tighten screws securely over the wire, and reconnect the modular plug into the jack. Close the box cover and tighten down the screw.
  11. Image titled Wire a Telephone Step 11
    Plug the phone company line back into the jack that you disconnected it from. Contact your local phone company and ask them to activate your phone line.


  • If the telephone company has not done maintenance on your home phone line for several years, you may have the older phone box that preceded the Network Interface Device. The older boxes are simply plastic or metal covers which are screwed on to the telephone wiring box to protect it from the elements. If you discover that you have an older phone box, contact the phone company. They will come to your home and replace it with a network interface device box at no cost to you.
  • If you are planning to install a new jack rather than use an existing one, please refer to the wikiHow instructions on how to install a residential telephone jack:


  • Be careful not to cut the wire insulation cover too deeply. It is very thin, and pressing too hard could result in cutting the wire itself.

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Categories: Cabling and Wiring Connection