You shouldn't hear anything on the line during a quiet line test. Report noise on the line to BT as a voice line fault (don't mention ADSL). Fixing the voice line fault can (but probably won't in your case) fix any ADSL problems.

In reply to a post by john2007:

(but probably won't in your case)

Any particular reason? Only asking as if there is a chance BT engineer says noise isnt line fault and stings me with £170 charge, then if there is no chance of this causing speed drop then not sure i want to do it

I shouldn't have included "(but probably won't in your case)". I suppose I can't see how that could add so much attenuation, but in fact I don't know.

The £170 charge relates to an ISP initiated ADSL engineer call out (and only applies if no fault is found).

Noise on the line is a voice line fault and I've never heard of a charge being made (line rental must pay for something).

In reply to a post by john2007:

I shouldn't have included "(but probably won't in your case)". I suppose I can't see how that could add so much attenuation, but in fact I don't know.

The £170 charge relates to an ISP initiated ADSL engineer call out (and only applies if no fault is found).

Noise on the line is a voice line fault and I've never heard of a charge being made (line rental must pay for something).

Yeah this is through Sky as i pay them line rental - not sure if guy knew what he was talking about, firstly saying if it was master socket faulty then id be liable for charging! and secondly saying his tests were 99% accurate to find a fault :|

Will get the engineer out to solve the hissing on the line and go from there, 1 problem at a time.