How to wire a telephone connection

Updated February 21, 2017

Your local telephone company often may only offer service for the portions of a telephone lines leading to your home. They may charge a high fee for wiring connections inside your home. Wiring a telephone connection is not difficult, especially if you only have one line.

Open the box on the outside of your home into which the telephone companies lines feed. This box is called a Network Interface Device (NID). The customer side of the NID usually opens via a single screw, although some may have more than one.

Verify the wire colours available on the customer side of the NID. Older phone installations will have green, red, black and yellow wires. In newer installations, the wires will be white/blue, blue/white, white/orange and orange/white. The standard changed a few years ago. The colours match as follows:

green = white/blue red = blue/white black = white/orange yellow = orange white.

Run telephone cable between your NID and the place you would like to place the telephone jack inside your house. Leave the cable loose for now, but make sure you have enough cable for the run.

Strip the ends of the wires. Around 1/2 inch of the red and green wires should be bare.

Connect the wire to be run inside your house to the green and red wires. Green and red are for your first line. Black and yellow are for your second line. Telephone lines only require two wires.

Open the telephone jack and screw it to the baseboard or wall in the desired position. Although most telephone jacks use a single screw as a wall fastener, some use double-stick tape for wall attachment.

Strip the ends of the red and green wires. Leave about 1/2 inch of the wires bare.

Connect the red and green wire on the telephone cable to the red and green terminals in the jack. This should complete your phone connection.

Plug a wired telephone in to the jack and test the connection. You should hear a dial tone. If you don't hear a dial tone, double-check your wiring. If everything is wired to the correct colours, call your telephone company to ensure that the line from the pole to your NID is properly connected. Verify that they are using the green and red wire pairs for your telephone line.

Disconnect the two wires from the jack once you have a dial tone. You need to finish the telephone cable installation.

Attach the cable to the outside wall using cable staples and a hammer. Cable staples have a piece of plastic that prevents the metal part of the staple from cutting in to the telephone cable.

Continue stapling and pulling the cable taunt until it is attached securely from the NID to the jack. You probably will now have some excess cable.

Trim the cable to about six to 12 inches longer than needed for the jack. This will give you excess for future splices.

Strip the wires and reconnect the red and green wires on the cable to the red and green terminals in the phone jack. You now have a new phone line.


Make sure that your cable is properly secured by cable staples to prevent snags and possible disconnects. If you are unsure which pair, red/green or black/yellow is used by the phone company, call your phone company's service desk. Most single-line installations use the red/green pair.


Although they are not high voltage, a ringing phone sends enough voltage over the wires to cause a minor shock. Be careful holding both wires at the same time.

Things You'll Need

  • Phillips and flat head screw drivers
  • Telephone cable
  • Knife or other wire stripper
  • Telephone jack
  • Cable staples
  • Hammer
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About the Author

Although he grew up in Latin America, Mr. Ma is a writer based in Denver. He has been writing since 1987 and has written for NPR, AP, Boeing, Ford New Holland, Microsoft, RAHCO International, Umax Data Systems and other manufacturers in Taiwan. He studied creative writing at Mankato State University in Minnesota. He speaks fluent Mandarin Chinese, English and reads Spanish.