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How to Wire Your Phone Jack

In the past, the phone company carried the responsibility not only to bring phone service to your house but to install wirings inside your property as well. Today, this is no longer the case.

When you subscribe for phone service to your house, your local phone company will only install a Network Interface Device, which is a sturdy plastic box mounted on your outside wall or basement.

Furthermore, you can still pay your local phone company to wire your phone jack. However, you can also choose to wire it yourself or seek the services of a licensed electrician to do the job for you.

Besides, wiring a residential phone jack is easy — but many phone companies charge steep prices for the service. And even if you pay for cables and modular jacks, doing it on your own will help you come way out ahead.

Phone Cables: In a Nutshell

In the past, phone cables usually consist of four colour-coded wires: red, green, black, and yellow. When extending a phone line across a room or another part of the house, you can use this one, or a newer Category 3 or 5 (Cat-3 or Cat-5) data cable.

Moreover, Cat-3 or Cat-5 cables have eight (8) wires with different colour schemes and are ideal for transferring more data, such as for a DSL internet connection. With either cable, once you’ve run them to the jack location, all that’s left to do is match up the correct wire colours.

Additionally, telephone wires that run through your home carry a low-voltage electrical current. That means you can work on them without necessarily shutting off the power. Also, only the phone service provider can shut off the power to your phone lines.

Despite that, practising safety precautions is of utmost importance. Hence, avoid working with wet hands or near moist areas and always wear your safety gears.

What You’ll Need

Wiring your phone jack with the right tools makes the job fast and easy. That said, here are the materials and tools that you’ll need.


  • Wire strippers
  • Screwdrivers
  • Needle-nose pliers


  • Telephone jack
  • Wood screws or drywall screws

Strip the Outer Sheathing

Using your wire strippers, remove about five to seven (5-7) centimetres of outer sheathing from one end of your phone cable. A traditional four-wire cable easily fits the 10-gauge slot on a standard wire stripper.

Next, rotate the strippers as needed to cut the sheathing around the cable while being careful not to cut the insulated wires inside. Pull off the cut piece of sheathing from the end of your phone cable to expose the inner wires.

Alternatively, you may come across cables that have pull cords inside. The pull cord strips the outer sheathing as you pull back on it. If so, remove only a small piece of the sheathing using strippers and use the pull cord to cut back five to seven (5-7) centimetres. Once done, trim off the cut sheathing using cutters or a pair of pliers.

Untwist and Strip the Individual Wires

Untwist each wire inside the phone cable from one another. Strip about a centimetre or two of insulation from individual wires using the 20 or 22-gauge slot on your wire strippers.

In most cases, you’ll only need to strip two wires if you want to install a standard one-line phone jack. However, you should use the second pair of cables if you are installing another line such as fax or second voice-phone line.

Identify the Wires You’ll Use

After stripping each wire, you’ll then need to identify which one you’ll be using.

For old four-wire cables:

  • Line 1 (primary phone line): Red and Green
  • Line 2 (secondary phone line): Black and Yellow

For Cat-3 or Cat-5 cables:

  • Line 1 (primary phone line): Blue and White-blue stripe
  • Line 2 (secondary line): Orange and White-orange stripe

Install the Mounting Plate

Let’s put your phone wires aside for now and install the phone jack mounting plate. To do that, start by removing the phone jack cover, exposing the mounting plate and a few mounting screw holes.

If the phone cables run inside the wall, you need to thread it through the opening in the mounting plate as you position the plate over the access hole.

On the other hand, if your phone cable is surface mounted, you only need to insert it through a notch in the side of your phone jack.

After that, mount the plate to the wall, moulding, or other fixtures using a screwdriver and drywall screws. You can also opt for wood screws, depending on the type of wall surface.

Additionally, some phone jacks have self-adhesive strips that quickly fix the plate against the wall. But if your phone jack has screw holes, Hills District Electrician recommends reinforcing the installation with screws.

Connect the Wires

Connect the stripped wires earlier from the phone cable to the matching screw terminals in your phone jack. Use the corresponding colour combinations of every cord that is pre-attached to it.

For old four-wire cables:

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

Cat-3 or Cat-5 cables:

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

To securely attach every wire connection, loosen each terminal screw using a screwdriver. Using a pair of needle-nose pliers, wrap the bare copper end of the wire around its corresponding screw in a clockwise direction.

After that, the wire insulation should come in contact with the screw terminal without any bare wire extending out from the screw. Leaving exposed copper wires results in short circuit or interference as wires from one terminal might connect with other ones.

Reinstall the Cover

Run a final check and make sure that everything is tight and snug. Afterwards, reinstall the front cover of the jack’s mounting plate. Depending on your plate, you can secure the lid with a screw or snap it into place.

Finally, plug a phone into the jack to make sure the line is live and is well-functioning.


With the right tools, knowledge, and skillset, you don’t have to depend on costly phone services to expand your telephone access at home. But if wiring a phone jack seems like a daunting task for you, Hills District Electrician is the only team you’ll need.

Our level 2 electricians will install and repair phone jacks, rewire telephone cables, and perform emergency electrical repairs with the best quality and craftsmanship.

With integrity, we are treating you and your property with the utmost care and respect. We are a team of licensed and insured electricians available 24/7 to accommodate you on your most convenient time.

Call us at 02 8378 2838 for an appointment or inquire with us via email.

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