Micro-filters question/clarification....


Prominent Member
Jul 2, 2003
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The Garden of England
I'm sure this is a very simple, but I'd just like clarification please.
I've been on NTL cable-broadband and have just moved so now have to use ADSL and the micro-filters.
I have 4 telephone sockets in my house, and will only ever use 2 of them - always the same 2 - ie the other 2 are now redundant...
Does this mean that I only need 2 microfilters?
Or do I need 4 - even though 2 of them will never have a phone attached?
Assuming you have one master telephone socket in the house and 3 extensions wired from your first socket then you actually need microfilters on ALL 4 extensions.

Bascially a microfilter is a high-low frequency filter. The low frequency is used for the telephone and the high frequency is used for broadband.

If you do not use microfilters then your phone may work but will probably have losts of background noise and your modem will probably NOT work.

The use of microfilter is the cheapest, ~£2 each but there are other solutions.

If your extensions are NOT hard wired i.e they come out of the master socket with a double/triple adapter (looks similar to microfilter) then all you have to do is put the microfilter in the master socket and add the extensions into. This means all other extensions have already had their frequencies separated.

The other method if they are hard wired would be to cut the lead from the master socket and fit a female socket and then follow above.

I must admit I only thought you needed to fit the filters to the sockets you are using only. Either with a telephone or with an adsl modem/router. So maybe someone else can chip in.
You only need to filter a signal if it is to be passed onto a non ADSL device (telephone, fax, modem, skybox). So if you never plan on using a particular socket it's fine to leave it. Also, modem/fax/skybox are likely to interfere with ADSL signals, so you have sky you may find they complain that your box never rings them.

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