Are DSL microfilters mandatory?

[ClubMan]

Purely out of laziness I never installed the DSL microfilter supplied with my UTV Clicksilver trial package but haven't noticed any interference on the voice line or degradation in data throughput when using both. Are these always required or only in certain circumstances? Why might they not be required?

 

[Dearg Doom]

They are necessary when there are telecoms equipment plugged in to the line that haven't been designed/tested with the additional high frequency signals that deliver your DSL (e.g. mismatching equipment can cause 'reflections' back on to the transmission lines). I found that most of my phones don't impact the DSL connection, but one (a Siemens Gigaset cordelss phone) caused the DSL synch to fail when the phone was picked up or put down. I put a filter on that and the problem is solved. The other phones remain filter free.

 

[ClubMan]

Thanks for the info DD. The phone in question is a Panasonic KTCD-950 DECT cordless in case that makes any difference. In any case I will probably install the filter(s) just to be sure but I was just curious.