Re: ADSL question
 

Inside a microfilter there is a direct connection between the line and ADSL terminals whilst between the line and phone terminals there is a low-pass filter.

This stops the phones from being upset by the high frequency ADSL signals and also prevents the phone from loading the line at high freqs and attenuating the ADSL stuff.

Filter/splitter - what's the difference?

If you really want a misnomer then how about a "shock absorber" on a car. Put your hand on one end and hit the other with a hammer (yes I tried it when I was small) and you'll find it does no such thing.

Re: ADSL question
 

Nothing much, was being a little Pedantic I spose (go away pedantic :p:) But Filter means to be that it does something active, whereas splitter says Passive.