try www.tpsonline.org.uk
tps - telephone preference service
fps - fax preference service
mps - mail preference service
MPS is voluntary and wil lonly affect direct mail. TPS should work well, I have been on for 2 years and have received less than 5 sales calls.
Incidentally, the overseas call centres are exempt from this, that is why I have received the calls.
Reinforcing aboe comments re TPS, so far all 'cold calling' has stopped since registering. It takes about 2 weeks to take effect from the date of registration. So far, so good.