Getting a noisy line (PSTN)

Basic troubleshooting for a noisy PSTN phone line

Annive avatar
Written by Annive
Updated over a week ago


  • Hearing any of the following while making a call: buzzing, crackling, static, screeching, or popping.

  • You may hear line noise when lifting the phone handset, even if not on a call.

  • While on a call, voices may be distorted or intermittently drop in volume.

Things to check first

Potential cause:

Poor signal or issue with the other caller’s phone service

  • If you only hear the line noise when you call a specific number, it may be the other phone service that has an issue. You can check this by making some test calls to different phone numbers.

Central splitter required

  • If more than three telephony devices or a Back to Base Alarm system, may need to contact an ACMA-approved electrician to install a central splitter.


  1. Unplug all devices from every phone socket, including your modem, telephones, fax machines, pay TV boxes and EFTPOS terminals.

  2. Plug a standard phone handset directly into the phone socket (without a filter), and then make a call, listening for line noise. If you are able to make a call without line noise, see the advice below.

  3. If more than one phone socket in home, plug handset (without a filter) into each of those sockets and make a call, listening for line noise. If you hear line noise when phone is plugged into one socket but not another, there may be a problem with home’s internal wiring.

  4. Using a different handset, repeat steps 2 and 3. If you hear line noise on the original handset but not a different handset, then the original handset may be faulty.

  5. If you no longer hear line noise, please see the advice below.

If still hear line noise on both handsets, contact us.

If you don’t hear line noise any more

  1. Plug handset into the phone socket with a filter and make another call, listening for line noise. If you hear line noise again, that filter may be faulty.

  2. Plug other devices back in one at a time and attempt to make a call after each new device is plugged in. Always start with any devices that are plugged in with a filter.

  3. If you suddenly start hearing line noise again, then the device just plugged in may be faulty or interfering with phone service, or it may be plugged in with a faulty filter.

  4. Replace the filter or device if it is faulty, or adding a filter to a telephony device if it didn’t already have one.

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