ADSL cable

I have decided to get BB and have just bought a Speedtouch 536 router. Currently for my dialup telephone modem I am using about 25 metres of a 30 metre telephone extension cable. Looking around for ADSL: extension cable it seems to stop at 20 metres (although I have seen cheap 25 and 30 metres once). I was wondering if there are reasons for the short length of ADSL cable. I might as well buy the cheap 30 metres but I would like to know if I can expect problems. Thanks. (Asks himself if he really needs Broadband)

Silly me. Being in old age is showing. A friend in Edinburgh has sent me a diagram demonstrating how using two filters I could have saved myself 6 pounds in ADSL cable by using the dialup flex to carry the ADSL to the filter. The idea of leaving a socket empty in the filter was anathema to my mathematical eyes. But two filters is the way to do it. Silly me.

A better way is to plug the router directly into the socket with a 1 foot phone wire, then running a long cat5 (network) cable to your computer. The latter cost peanuts, say