This is exactly what I do and it does appear to reduce the number of calls significantly - I get two or three a day between my two cell numbers and work phone b

This is exactly what I do and it does appear to reduce the number of calls significantly - I get two or three a day between my two cell numbers and work phone but not every day. I also noticed scammers are trying to counter it by asking to press multiple keys e.g. a recent "final courtesy call about your extended car warranty" first asked to press 1 to talk to the operator, than it asked to press 3 if my car had some number of miles then it just asked to press 8 without any other prompts. So people getting to the operator seems to hurt them if they are willing to drop a certain number of potential chumps who will mess up multiple phone prompts.