>> because it only has RJ11 connections which won't fit into my phone socket and thus I need to connect a filter to the socket in order to hook it up.
Thats fine - I was confused that the mention of RJ45. adsl modem cable should use RJ11 so that it can only be plugged into a filter as adsl frequencies are much higher than telephone voice frequencies. When you have adsl you need to make sure that every telephone device (including fax machines and sky boxes) is plugged into an adsl splitter.
>> I'm not entirely sure what the purpose of this built-in filter is.
I presume the back of your router looks like this -
http://www.zoom.com/products/x6_back_panel.htmlI strongly suspect its not an adsl filter but more to do with something else. The telephone device will be to do with VoIP.
From the
data sheet"The X6 has easy-to-use Quality of Service (QoS) to guarantee upstream speed when you need it for applications like on-line gaming and Internet Telephony, // Mac address filtering, // Ports Filtering. "
and
Voice over IP telephone adapter or other device plugged into those ports is then provided with the guaranteed upstream bandwidth selected by the user.
VoIP uses the same frequencies as adsl (Voice Over IP), hence you still need to plug it into a normal adsl filter.
Filters and phone adapters:
Filters and/or phone adapters may be included in some markets. Please
check the package for specifics or ask your dealer. An ADSL filter allows a
telephone, facsimile machine, or other telephone instrument to be used even
when you are online with your ADSL modem.
What that means is that in the UK you should have been sent / need to use a filter.
The exception would be if you have an adsl filtered NTE5 faceplate.
