If you want to test for noise, Grab a phone and plug it straight into the test socket, Dial 17070 then numer 2 if theres any noise there then its BT's problem and its free so get em to sort it.

If theres no noise then plug your wiring back in filter etc and do the same again if you find there is noise then fit a filtered faceplate from adslnation.com

Then repost stats.