Broadband - Noise and Interference on phone line

Published 12/05/2004 12:13   |    Updated 03/03/2008 16:07

Since getting broadband I can hear noise and interference on my telephone line, what should I do?

Firstly ensure that you have attached a microfilter to every phone socket in use in your premises.


An ADSL microfilter is necessary because once your line is activated with Broadband it carries two signals - an analogue (phone) signal and a digital (broadband) signal which are both carried at different frequencies. In order to receive both of these signals clearly you must connect all of your devices which normally plug into a phone socket into a Broadband filter. It is this feature of Broadband which allows you to use the Internet connection whilst on the phone or receiving faxes.


If you do not connect your Broadband filters or you do not have all devices within your property connected using a Broadband filter you may face the following problems:

  • No connection possible on Broadband service: common symptoms include a flashing ADSL light on your modem.
  • Intermittent Dropping Internet connection
  • Fuzzy or bad telephone connection when the modem is plugged in.

Please ensure that every telephone socket in your premises has a microfilter attached. It is not necessary to attach a filter to a socket that is not in use. The BT Installation Kit includes three ADSL microfilters, 1 double socket and 2 single socket. If you have more than 3 telephone sockets in use you will need to purchase additional microfilters.


Unfortunately BT do not supply additional microfilters, however microfilters can be purchased from any major electrical or computer retail outlet.


Click here for installation instructions for ADSL Microfilters.


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