*EDIT* That's a really useful resource site, thanks for sharing I think it's worthy of living in the favourites section.
Personally I have found the best way to stop unwanted calls is to activate something called "Anonymous Caller Rejection" (aka ACR) unfortunately this service costs with BT but I'm on NTL and it's free to use
I then registered with the "Telephone Preference Service" (TPS) and virtually 99% of all annoying telephone calls have been eliminated I still get the odd 1 every now and then from companies based abroad but they are usually few and far between.
The TPS also has a sister service called MPS - "Mail Preference Service" You can use this to stem the flood of junk mail to your doorstep to a trickle.
A shame no equivalent service exists for spam emails
Personally I have found the best way to stop unwanted calls is to activate something called "Anonymous Caller Rejection" (aka ACR) unfortunately this service costs with BT but I'm on NTL and it's free to use
Sorry for hijacking the thread, I just tried to call my cousin in the US using a low cost carrier Alpha Telecom (I usually use One Tel). Anyway I got an automated message in an american accent saying that the number called does not accept calls with witheld ID's (or something to that effect). I just re-dialed on BT and got through no problems.
Maybe I'm being cyncial but I wonder if maybe the phone companies are getting annoyed that they're losing revenue to least cost carriers & VOIP providers such as Skype?