BT owns the stuff up to the master socket, i.e. from pole or underground, into the house and terminated on a socket usually marked with BT. After that point then you can run additional sockets using cat 3 or 5 to secondary sockets which have no internal components. You can convert a master to secondary by removing the ringing capacitor, line resistor and surge protector. you connect cables 2,3 and 5 together preferably using the std colours of 2(blue/white) , 3(orange/white) and 5(white/blue). Always best to leave the master where it is and run secondaries around the house simply daisy chaining the remembering that more than 5 phones and you may have trouble getting them to ring, also if its a broadband line you need a filter with every phone/fax connected, hope this helps
P&S - ex BT