How to Run a Phone Line Extension

Running a phone line extension to another part of your house yourself can be easy and save you a bundle.

Run a Phone Line ExtensionRun a Phone Line Extension
This eHow applies only to running an extension, not adding a second line, which is best left to the pros.

Consider first whether you need to start running the wire from the main box (where the phone line enters your house or apartment) or whether you'll tap into an existing jack (where you connect the phone itself) on an inside wall.

Remember that if you go into the main box, you'll first have to figure out how many phone lines your house is wired for, and how many wires each phone line requires. (Two wires in old homes, six or more wires in newer homes.)

Figure out the best route to the new jack's final destination, whether under the floor (if the house is not on a slab), through the attic, along an outside wall or directly into a room.

Buy enough phone line to reach the new location, with the number of wires matching what each phone line in the box already requires.

Note the positions and colors of the existing wires before you do anything, writing them down on a piece of paper.

Take all existing phones off the hook, which will prevent an incoming call from generating a ring voltage which may cause a shock.

Strip the wires on one end of your new phone line about an inch back and attach in the main box or jack. Phone wires always attach with screws, usually just by wrapping around the screw and then tightening.

Match wires by position if wire colors are different.

Cut off any excess wire. Close the box.

Attach each color wire to its correct post on the other end of the wire, and screw the new jack to the wall.

Use cable tacks or staples liberally to make the line as unobtrusive - and well-attached - as possible.

Things You Will Need

  • Paper And Pencils
  • Utility Knives
  • Screwdriver Sets
  • Small Hammers
  • Wire Strippers


  • Make sure you buy enough phone line to run along the edges and corners of the room and up around doorways, rather than across the floor.
  • Phone wires and jacks are delicate compared with electrical outlets; be gentle.
  • Whether you start your new wire from the main box or an inside jack, the best way is to attach the wires directly, rather than using a splitter. But if you're not going too far a distance, a splitter is easier. Be aware that splitters can be problematic and cause signal disturbances, which can be troublesome for sensitive machines such as computer modems and even fax machines.


  • Though you're not very likely to get a shock (at least a strong one) while working on a phone line, still be very careful: Never stand in water, and stay away from any other wiring you may encounter. You don't know who else has been through there.
  • If you decide to tap into the main box and other people have phone lines coming through, you may cut them off and create far more trouble and costs (both monetary and emotional) than it's worth.
  • If you are intent on adding a second line (for a second phone number) yourself, remember that the phone company will still send a bill for "installation" despite the fact they never visited your home in person.