When troubleshooting ADSL issues there are 2 tests that you can do to help you troubleshoot your problem. They are :

Quiet Line Test

1. Unplug any extension phones, extension cables, answer machines or fax..
2. Plug a normal touch tone phone directly into the BT master socket.
3. Dial 17070, press option 2 (quiet line test)
4. You should hear 'Quiet Line Test' and then silence, there should be no pops, clicks, whistles, buzzing etc.

If there is noise on the line, make sure it's not your phones connection to the socket (wiggle it about a bit) and that you are using the master socket. If you are sure its the line making the noise then dial BT and report the fault, they should be able to sort it out.

Distance From Exchange

1. Dial the same line test number as the quiet line test (17070). Then press option 3 (fast test) then press option 1 (to say you are authorized).
2. The press option 2 (ring back test). Then put the phone down.
3. You will get called back by the test facility within about 10 seconds, one of the bits of information given will be distance from exchange (in kilometers).

The distance result may not be 100% accurate but does serve as a guide.