Expert Advice on Home Improvement TV Host of Emmy®-Nominated Today's Homeowner® and home expert for The Weather Channel

How to Fix a Hum in a Phone Line

Electrical and Lighting, Repairs and Installation, Ask Danny Published 06/25/2008 by Danny Lipford

I have a loud hum in our telephone line. The phone company says it’s inside the house. Is there any type of a device that can locate the cause of the problem? - Jim

Hi Jim,
There are a number of things that can cause humming or static in a phone line including a short in the wires, a defective phone, interference from power wires or light fixtures, and a signal from another electrical device. Here how to go about isolating and repairing the problem:

• First, check to be sure the hum is coming from inside your home by opening the telephone interface box, disconnecting the test jack, and plugging a corded phone into it. If you still hear the hum, then the problem is with the phone company. If it stops, the problem is inside your house.
• If it’s inside, plug the house jack back into the interface box and unplug each phone in the house one by one while listening in on another extension. If the hum disappears, the problem is with the phone you unplugged.
• If the hum persists, disconnect each set of wires one by one from the terminals in the interface box, and listen on an extension until the sound stops.
• Once you’ve isolated the problem wires, check the connections at the jack, and try unplugging any electrical devices nearby that could cause interference.
• If you’re still having problems, hook the other two color coded wires in the cable to the jack and interface box.
• As a last resort, permanently unhook the defective wires at the interface box and run a new line from the interface box to the jack.

You can find out more about working with phone lines in the articles How to Install a Phone Jack and Replacing a Telephone Jack on our website.