I'm with talktalk who I know get a bad press sometimes, but they offer lots of free things like caller display, call safe and last number barring. If someone phones from a withheld number, they are asked to say their name followed by the hash key. I am then given the opportunity to press one and add them to my list or press 2 to accept on this one occasion and so on. Once they are on my list they don't have to say who they are in future calls. If I accept a call and I shouldn't have done, I can then bar that number. Haven't received any scam calls since I've been on this.