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What are microfilters and how to use them

What microfilters do, when you need them, how to connect them correctly, and how to troubleshoot common issues.

What is a microfilter?

A microfilter is a small device that stops your phone and broadband signals interfering with each other. Without microfilters you may experience slow broadband speeds, connection drops or noise on your phone line.

Microfilters have two ports:

  • ADSL/DSL port: for connecting your router.

  • Phone port: for connecting your telephone, digital TV box or answering machine.

A microfilter showing the ADSL/DSL port for the router and the Phone port for a telephone or other device.

Do I need microfilters?

You only need microfilters if you have a standard master socket (one port on the front). If you have a pre-filtered master socket (two ports built in), your phone and broadband signals are already separated and you do not need them.

With a standard master socket, you need a microfilter plugged into every socket in use. Two microfilters are included with your router. If you need more, you can buy them online or from any electronics retailer.

A standard master socket requiring a microfilter compared with a pre-filtered master socket that does not.

How to connect your microfilters

  1. Remove any devices plugged into your master socket.

  2. Plug your microfilter into your master socket.

  3. Connect your phone cable (or other device) to the Phone port on the microfilter.

  4. If this is the socket where your router is connected, plug the broadband cable from your router into the ADSL/DSL port on the microfilter.

A microfilter connected to a master socket with the router in the ADSL/DSL port and a phone in the Phone port.

Troubleshooting microfilter issues

If you are experiencing broadband or phone line issues, check that:

  • You have not plugged two microfilters into each other.

  • You have not plugged a microfilter into a socket that is not in use.

  • If you do not have enough microfilters for every socket in use, unplug devices from the sockets without microfilters until you can buy more.

  • If a microfilter may be faulty, try replacing it with a spare to see if the issue is resolved.

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