How to troubleshoot for static or noise on your phone line, or no dial tone

Interestingly, noisy phone lines and phones without dial tone have something in common . You start troubleshooting the cause of both exactly the same way.

If you hear static or noise on your phone line, or aren't getting a dial tone, we can help.

Step 1: Isolate the source of the trouble

The first thing to do is locate where the issue is originating. Is there a problem with the wiring outside your house? Or is the problem originating from within your house? Testing your line before contacting CenturyLink could save you time and trouble, and it's easier than you might think.

If the problem is outside the home, you'll want to contact us to schedule a repair. But if the root cause is inside the building, it's the property owner's responsibility. Later, we'll review how to diagnose a problem originating inside your home. But for now, let's figure out where the connection is broken:

You can determine whether the problem involves inside or outside wiring by performing a simple test on the Network Interface Device (NID).

What's a Network Interface Device (NID)?
A "NID" is the box where the inside wiring connects with the outside wiring.  

It's usually attached to the outside of your house or building where other utilities, like your electric meter, are located. Look for a rectangular plastic box. It's gray, but customers sometimes paint it to match the color of the house or building. Occasionally, an outdoor-type NID is located inside a basement, garage or utility area of the house.

Apartments or condominiums may have an indoor-type NID, which is usually a special phone jack located in the kitchen.

Outdoor NID

Indoor NID

Your residence can have an outdoor or indoor NID, but not both.

What you'll need to test the phone line coming into your house:

  • Flat head screwdriver
  • A corded telephone, where the receiver is physically connected to the phone (here are some photo examples of corded phones), that works. If you are unsure whether your corded phone is working properly, borrow one from a neighbor.
  • Phone cord

Let's get started . how to determine whether the problem is inside or outside.

Before you begin, you can print these instructions (PDF) to bring with you outside.

If you have an outdoor NID:

  1. Take your working phone to the outdoor NID.
  2. Open the NID box by unscrewing the fastener marked "Customer Access."
  3. Then, find the test jack inside and remove the plug from it.
  4. Plug your working phone into the test jack.

Outdoor NID
Step 2

Outdoor NID
Step 3

Outdoor NID
Step 4

Is there a dial tone? Does it sound clear?

If you have an indoor NID:

  1. Take your working phone to the NID inside your house.
  2. Unplug the cord that is plugged into the jack marked "Test Jack." The test jack will probably be located on the bottom of the NID.
  3. Then plug the working phone into the test jack. (Note that the indoor NID may or may not have a conventional phone jack in the middle of the cover plate.)

Indoor NID
Step 2

Indoor NID
Step 3

Indoor NID
Step 4

Check to see if you hear a clean dial tone.

Important! Once your testing is completed, reconnect the test jack back into the NID and if outside, close the box.

Good job! So, did you experience the same problem at the NID?


What it means

Next step

YES, you experienced the same problem at the NID using a working phone, as you did with the phone plugged into a jack inside your home.

Most likely it's an issue with outside equipment or phone lines.

Submit a repair request ticket so that CenturyLink can fix the problem.

When CenturyLink comes out to repair this issue you probably won't have to be there. As long as we can get access to your property, meaning you don't have a locked gate or fence, a dog outside, or live in a gated community.

NO, the phone works correctly when plugged directly into the test jack inside the NID.

The issue is inside your home or building and you may be able to fix it yourself.

Go to Step 2 below.

If your home doesn't have a NID or the NID could not be located, it may not be possible for you to determine the source of the phone problem, but you can still check the equipment and phone jacks inside the house.

Step 2: Examine the jacks inside your home

If you're getting a clear dial tone from the NID, then you may be able to fix the issue yourself. We know the problem is somewhere inside your house or building, so here's what you can do:

  1. Make sure the receiver of each telephone in your home is hung up correctly. If you find that a phone is off-the-hook, hang it up properly and then recheck after a short while to see if this has corrected the problem. If you determine that all phones are hung up properly, but the problem still occurs, continue to #2.
  2. Unplug all telephones and other equipment plugged into the phone jacks in your home. This includes all phones, answering machines, cordless phones, modems connected to personal computers, satellite systems, security systems, Caller ID boxes, etc. Be sure to unplug each of the devices from both the telephone jack and the electrical outlet, if the device uses an AC adapter.
  3. Once all devices are unplugged, using a corded phone that you know works properly (if unsure, borrow one from a neighbor), plug it into each jack, one after the other. Check at each jack for a clear dial tone. It may be as simple as having a loose jack connection or a dead phone battery which is easy to fix.

Did the phone work?


What it means

Next Step

YES in all jacks

If the working phone works on all jacks, then one of the other phone devices you normally plug into your line, or one of the phone cords being used to plug them in, is likely causing the problem.

Plug each of the remaining phone devices in, one at a time, to the phone jack (and AC power, if required), until the problem begins to occur again. This helps you isolate and identify the problem equipment.

Check whether the device contains batteries that need to be replaced.

Replace the phone cord to that device with one that you know works.

Did you fix the problem after you submitted a trouble ticket? You can cancel your trouble ticket online.

YES in at least one jack

If the working phone worked when plugged in to at least one jack, but failed to work on other jacks, then the problem is probably with your inside wiring or phone jack(s). Inside wiring, phone jacks, phones and equipment are a customer responsibility.

If you subscribe to CenturyLink Inside Wire Maintenance (called Line-Backer™ in some areas), CenturyLink will normally make repairs to inside wiring and jacks at no charge to you.

If you do not subscribe to Inside Wire Maintenance, we can repair your inside wiring for a fee or you can hire an electrician or home-repair specialist if you are unable to correct the problem yourself.  If you are unsure, please chat with us.

To have CenturyLink repair the problem, submit a trouble ticket.

NO the phone didn't work in any jacks

If the working phone had a clear dial tone when plugged into the test jack inside the NID, but didn't on any of the jacks inside your home, then the problem is probably with your inside wiring or phone jack(s).


If you did not test at the NID, and the working phone did not work on any of the jacks inside your home, then it cannot be determined at this point whether the problem is inside or outside your home.

  • If you have CenturyLink High-Speed Internet service, you may need to use DSL filters on phone jacks that connect to devices other than your modem.  When DSL filters aren't used or installed correctly, you may experience static or a hissing sound on your telephone line. Chat with us for more information or to order more filters.
  • If you have a burglar alarm system, you may also want to contact your security company because:
    • Burglar alarms are sometimes spliced directly into the phone line.
    • A short in the burglar alarm system could cause the line to go dead, resulting in the loss of dial tone.