How to Add a Phone Extension

Back of phone wall jack.
Back of phone wall jack with phone line attached.

Can you run an extension line off an already in use phone jack to a room which may not have one? – Robert

Hi Robert,

It’s not hard to extend a line from an existing phone jack to a new one in another room.

Simply unscrew the existing jack from the wall, and attach the color-coded wires for the new cable to the matching terminals.

Then run the cable to the new jack and attach the matching wires to it.

For more information about working on phone lines, check out our articles on:



  1. I tried the above method of running a cable from an existing jack to a room that has no jack but my internet failed. My intent is to have the existing jack still function (work) while I run a wire to a room that has no jack. Any recommendations?

  2. My network interface had a small grounding wire going to a cold water pipe. I think it was connected to the yellow (unused) terminal. However, in everything I read online or on paper about wiring makes no mention of a grounding wire.
    What do you think?


  4. I am eliminating my business line in adjacent room, but would like to use the phone jack/extension in our bedroom to keep the internet service associated with the computer in the adjacent room.
    Do I merely take the black & yellow lines associated with the business line and combine them with the red & green lines for the home phone? And, if so, do I put the black line under the red; and, the yellow under the green?

  5. Hi and thank you for your time. I have an existing jack in my livingroom with a phone cord plugged into it. I want another phone in the livingroom and would like it to have its own jack that I will connect to the baseboards. Are you saying that I can simply
    1)remove the cover from the existing jack
    2) Take 10 feet or so (as needed) of extra phone wire and stip it to display colored wires;
    3) combine those added wires to the existing wires so there are 2 red wires going to the one screw and 2 green wires going to the existing greeen screw
    4) strip the other side of the added phone wire and attach those wires to the new jack?

  6. what due the colors mean in the phone jack
    i know that there are red green yellow and black
    why due we have those colors and what due they due each one

    • Hi Dand,
      The color of the insulation on each wire in a phone cable is used to identify which wires are which on both ends of the connection. The wires are the same otherwise and can be interchanged as long as you use the same two colored wires on each end of the connection. For example, if you attach the red and green wires to the terminals in a phone jack, you need to attach the red and green wires to the terminal on the other end of the line as well. Usually the red and green wires are used for the first phone line in a house, yellow and black for the second line, and blue and white for the third. But if the other wires in a line aren’t being used, you can use them instead. This is particularly handy if one of the wires you’re using has a short in it and no longer works.

  7. My computer is in the basement and my phone lines are upstairs. I have not been able to use my fax machine due to this. I have a wireless system can you tell me what to do and the necessary supplies to get from the hardware store. Thank you so much

  8. I have a 5 wire telephone line (blue,white,white/blue,yellow,black) this is for line 2 cause line 1 is red green. what colors go to red and green terminals in the interface box. when i hook up the white to the red term. i have dial tone on line 2 but lost dial tone on line 1. thank you

  9. hello does anybody make a wireless router for home phone lines i need to put a land line in 4 rooms but have 1 in living room . thanks

  10. want to put phone in kitchen but no jack, but there is a box with the wire in it but it’s for the jack in the adjacent room. How do I add a jack in the kitchen using the same wire ?

  11. I’m having trouble with my phone line ever since a satellite tv tech has been out here working.In the customer access panel I had two different wires leading off of the same line (two red wires to one screw and two yellow wires to one screw) Now nothing works with this configuration.If I disconnect one of each color wire the remaining wire is sound and works.Likewise the other way around.Is there anything that I should look for?This has always worked in the past…thanks in advance!

  12. how do i hook up a wall phone wire is there green,red,yellowand black. but the red wires have wax like material on them do i remove it or what. please help me

  13. This article needs either more detailed descriptions or more pictures to be useful. It has only one picture and three sentences. Not enough to make it clear to a newbie. If you know how to do it then I’m sure this makes perfect sense, but it’s not clear to someone who hasn’t worked on phone lines before.

    • Raul,
      Thanks for the feedback. You might want to check out the links at the bottom of the post to the other articles as they have more step-by-step instructions and images.

  14. Hi I have an old style yellow plug socket from a phone that has a crack in it. Is that easy to fix? I may be a girl but I can fix a lot.

  15. I want to run a new phone line to a room in my house. Which screws do I use in the box installed by the local phone company (outside). I then use the same screws or colored wires to connect the wall box inside, is this not correct?

  16. I moved my landline phone from the kitchen jack to a bedroom double jack. Only one half of the double jack was live so I used a splitter to share the single live half of the jack with my computer but now the jack in the kitchen does not have a dial tone.

  17. i have recently connected to NBN there was no phone jack near the box ,now i have one phone.
    Can i get wireless extensions for my home, because the phone wiring is now dead

  18. I am remodeling my kitchen and would like to move the existing phone jack to a new location about eight feet away on the same wall. I could connect to the existing jack and run a new wire over, but I would really like the original jack to be gone and dry walled over.
    I know I could splice the wires, or maybe even better, use an inline coupler, but I know you should always make electrical connections accessible in case of a problem. I know phone lines are low voltage and not sure if the sale rules apply.
    Is that inline connector going to be trouble free for 100 years, or would splicing and/or using a coupler be punishable by death?
    I don’t like doing anything Mickey Mouse, and using a coupler behind a wall sounds like it might be close. I was thinking a couple enclosed in heat shrink tubing??? To run a new line from the outside phone box is out of the question due to the extreme distance.
    Speak to me oh spirit of A.G. Bell, guide me on my adventure.
    Thank you for any information you provide

    • Hi, Julie!
      Selected questions will receive a moderator’s answer, as the comments form states.
      It’s not possible to answer all the questions we receive, due to the high volume, but we sure do our best!
      Thanks for visiting

  19. We built a new home and put phone lines in three rooms, we decided to add a new line, the other are connected to each other, how do we need to connect the new line to the others? The phone company told us to get a junction box. New line is going to be DSL Internet.


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