How to Hook Up a Second Phone Line

Interlaced phone connector jacks close-up.
  • 2 hours
  • Intermediate
  • 35
What You'll Need
Phone jack
Double phone jack
Wire stripper
Landline phone
What You'll Need
Phone jack
Double phone jack
Wire stripper
Landline phone

"Christmas trees and bumblebees." No, it's not a strange nursery rhyme; it's how you remember how your phone lines are distributed. On the back of the phone jacks, there are usually four connections—one red, one green, one black, and one yellow. The red and green ("Christmas trees") wires to power the first, or primary, line in your home. The black and yellow ("bumblebees") wires don't get used unless a second line is added to your home.

Adding a second line to your home is an easy task that even the least experienced do-it-yourselfer can do without costly interference from a telephone technician. First, let's look a few scenarios where someone may need a second line in their home:

A home office may require a dedicated line for business purposes.

You may have children who need their own line so that they stop tying up the main phone line.

Many people like having a dedicated number for faxes.

Dial-up ISP users may want a dedicated line for their online surfing.

We'll also go over adding a line to a room that currently doesn't have a phone jack, so you will be able to pick and choose where you want the second line to be located.

Step 1 - Activate the New Phone Line

The first step to adding a second line is calling your phone company. Tell them that you want a second line added to your account. They will go over all the options that you can include on the line like Caller ID, Call Waiting, etc. Keep in mind that the more options you include, the higher the charge will be for the line.

Tell your phone company that you will be doing the wiring inside your home. Once everything is set, they should give you the new number and a date when the work will be completed.

The phone company's technician will come to your house and check for service at the Network Interface Device (NID) on the side of your house. Once he makes any necessary connections or repairs, the second line will be ready to go, and you can do the interior wiring yourself.

The phone wire currently running through your house can handle two lines. Remember the "Christmas trees and bumblebees"? The yellow and black wires will now be carrying the second line, while the red and green will carry the primary line.

Step 2 – Unscrew the Faceplate

If you have a certain room, like a child's room or an office, where you want the second line, the switchover can be simple. In the specified room, find the desired jack for the second line, and unscrew the faceplate from the wall. On the backside of the jack, unscrew the red and green wires and make sure the black and yellow are connected.

Step 3 – Connecting the “Jumper” Wire

If you need to connect the black and yellow wires, simply strip about 3/4-inch of insulation off with wire strippers, and connect them to the screw that already has the same colored "jumper" wire on it.

Step 4 – Check for a Dial Tone

Don't screw the plate back on yet. You need to check for a dial tone. Plug in a landline phone (one that doesn’t need to be plugged into a power source) and listen for a dial tone. If you hear it, dial your primary number. If the other line in the home rings, then you’re set.

Step 5 – Re-install the Faceplate

Wrap the red and green wires back down the phone cable and tape the ends with black electrical tape. Then, re-install the faceplate to the wall.

Step 6 – Final Touches

Don't get too excited! You're not done yet. Go to each of the outlets in your home where you don't want the secondary line and remove the black and yellow wires from the terminals. Wrap and tape them as described earlier. Some people may say you don't need to remove the wires, but for the time it takes, it can save you some potential issues down the road. Lastly, double-check for dial tones at each outlet while you're working on it.

If your phone in your home office is capable of having two lines, then you don't have to remove the wires from the back of the jack. With all four wires connected, the phone does the work of identifying which line is ringing.

If you have a room with only one phone jack but you want two-line access in that room, there's a simple remedy. Head to your local hardware store and pick up a dual phone jack plate. It has two jacks on it, one on top of another. Simply hook the red and green to the top jack and the yellow and black to the bottom jack, and you now have two-line access in the same room without having to run additional wires.

Continue to Part 2: Installing a New Phone Jack