Do not, in any circumstances, touch the incoming lines.
Yo do not know who they belong to or where they are going. You will be breaking the law in two ways. Firstly by interfering with the BT network and secondly potentially intercepting communications not intended for you. And as you do not know what you are doing you could quite easily damage part of the network.
Potentially, save a pound and loose the company.
Be assured that BT security do actually monitor these forums, and will not take long to track you down and monitor your activities.
M H C
taurus excreta cerebrum vincit