I have recently moved house and the existing BT socket is a Split type with a front face that has both telephone and asdl socket.
Does this mean I can only plug my router into this socket?
Yes.
Can I extend it and do I still have to use filters?
There is no need to use filters anywhere with that arrangement. In effect the socket has created two separate circuits. One of them is for telephony, the other is for broadband.
You can extend the broadband circuit if you want but I'd recommend using good quality cable. It may only be a small part of the total length back to the exchange but that kind of socket is the best way to install ADSL and it's a shame to negate the benefit by running a long length of cheap cable from one end of your house to another.
Actually the best solution would probably be what I've done. Site the modem near the socket then use a combination of switches and Cat6e cable to distribute Ethernet sockets around the house.
Edited by Andrue (Thu 10-Feb-11 15:19:55)