In reply to a post by Ewok:

When I do a quiet line test using a wired (not DECT) phone to the test socket, I can hear a feint hissing sound constantly, but IDNET have tested the line and it passed the test. When I was on the phone to IDNET support I could actually hear a much louder buzzing type sound on the phone which he could not hear from the other end.

I am surprised that no one has picked up on the above.

From a reading of your description, it seems as if there is a joint starting to have HR or semi-conductive tendencies.

With regards as to your DIY fitting of an NTE5, what is the method of connection of the pair to the the rear of the socket? Screw terminals? IDCs? Have your re-checked those connections to ensure that they are good?

They are IDC's, I used the plastic punchdown tool that came with it. I was wondering whether to whip the connections out and re-do it just to make sure.