Unstable ADSL phone line voltage weirdeyness

[prehensile]

I've just changed the ADSL wireless router to the loft and now the ADSL connection drops every half an hour, especially when there is a phone call. The strongest signal seems a bit slower than normal and really unstable.
on the other fork of the phone line it was totally stable even when the phone was used.
my dad did the phone wiring on the line the router currently is fixed to where it splits between the portable phone and the router, In the loft, behind the panelling, which is a mission to get to for rewiring.
I think perhaps the phone line is linked to one of the wrong neutrals or something, and I've seen that there is a voltage drop from 50 volts to just a couple of volts every time there is a phone call.
There aren't any microfilters on the line at the moment, but there weren't any when I had excellent ADSL signal strength, so I think I have to improve the line even before fixing on any microfilter, any ideas what could be happening? Thanks!

[Steve]

It's probably wired slightly wrong. Phones use wires that ADSL modems don't to signify when the received is hung-up or not, so I suspect that your problem lies there.

[prehensile]

As far as I know, ADSL modems and phones both use the same lines, they only used two lines, technically called pots, which is just a charge to wire at 30 volts + and a neutral wire.
Because it's only two wires, I don't know how it could possibly be wired wrong, except the wrong neutral perhaps, so that the voltage would drop completely every time the telephone is used. Does anyone know? Is this normal? Perhaps I'll try to GI my way right around the roof installation space in the loft. I hope I can say something!

[Steve]

Dunno if this will help:

http://www.wppltd.demon.co.uk/WPP/Wi...telephone.html