Since people often mention the 'quiet line test' or ask 'how do I find out how far I'm away from the exchange', here's some simple instructions
The BT line test facility can be accessed from any BT (or WorldOnline) line by dialling 17070.
Quiet Line Test
Unplug any extension phones, extension cables, answer machines or fax (anything except the phone you will use to do the test!).
Plug a normal touch tone phone directly into the BT master socket.
Dial 17070, press option 2 (quiet line test)
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 (or WorldOnline) and report the fault, they should be able to sort it out. Remember that 'mis-reporting' a fault (e.g. if it turns out to be your phone, extension cord etc.) may be charged a call-out fee by BT (/WOL).
Any problems? See It doesn't work? (below)
Distance From Exchange
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 authorised, don't worry about 'not being officially authorised'). The press option 2 (ring back test). Then put the phone down.
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 kilometres).
*The distance result may not be accurate if you have a 'DACs' fitted. It is not 100% accurate but does serve as a guide.
Any problems? see It doesn't work? (below)
It doesn't work?
It doesn't work?
You need a BT line (or WorldOnline).
You need to use a touch tone phone (don't think it works without one).
You have caller line id (CLI) blocked, if this is the case then on dialling 17070 the message will include 'there is no CLI detected for this circuit'. You can get round this by dialling a prefix before 17070, the prefix is 1470, so the full line test number will be 1470 17070.