How to Wire a Phone Jack

Need to Hook up a Phone Jack? Here's the Right Way to Do It

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Phone jack installation is one of the basic wiring jobs homeowners can do. Home automation applications may include installing phone extensions in additional rooms or installing a second phone line in the house.

Automation enthusiasts continually look for ways to make their homes more convenient, and installing additional phones is one of the ways they do it.

Before getting started, map out where in the house that the phone jack should be.

Consider where any desks or tables might sit so that you can avoid having wires stretched to their limits or hanging between desks.

Types of Home Telephone Wiring

Telephone cable typically comes in the 4-strand wire, although 6-strand wire and 8-strand wire are not uncommon. The various strand types are referred to as 2-pair, 3-pair, and 4-pair.

A conventional 4-strand telephone cable normally has 4 colored wires that include red, green, black and yellow.

Installing Single or First Phone Lines

Although most telephones use 4 or 6 contact connectors, standard telephones only use two of the wires. Single-line telephones are designed to use the 2 center contacts in the phone connector.

On a 4-contact connector the outside 2 contacts are not used and on a 6-contact connector, the outside 4 contacts are not used. This is important to know when wiring the phone jack.

Whether you are installing a modular surface mount or flush mount jack, the wiring is the same:

  1. Remove the front cover. The inside of the connector is wired to 4 terminal screws. The wires should be red, green, black and yellow.
  2. Connect your hot phone wires (red and green) to the terminals with the red and green wires.

    Note: Although red and green are commonly used for hot phone lines, older or improperly wired homes could have other colors in use. To ensure you’ve got the right wires, use a phone line tester to check that the wires are hot. Another easy way to check the wires is to hook them up to the terminals, plug a phone into the check and listen for a dial tone.

    Installing Second Phone Lines

    Most homes are wired for two phone lines even if only one line is in use. It’s very common when ordering a second phone line for the phone company to activate the second line remotely without ever coming to your home. When they do this, they are turning on your second pair (the black and yellow wires).

    Remember that the outside contacts in a single-line phone connector aren’t used. Two-line phones often make use of this outside contact pair so that no extra wiring is required (providing you have the black and yellow wires connected inside the jack).

    If you plan on using a single-line telephone for your second line then a modified phone jack will need to be installed.

    1. Remove the front cover of the phone jack and connect your yellow and black wires to the red and green terminals. This will cross your second phone line to the center connector contacts so you can use a standard single-line phone.
    2. If you experience problems, use a phone line tester to ensure the new second line is active.