I very very seldom answer but when I do and it is a Telemarketer I just give em a big ole "F YOU" and hang up..
The robot doesn't care. I don't even waste my breath on them. I have to pick up my phone due to my job, spammers just get a hangup.
The telcos are starting to realize that it harms their bread and butter product. The messenger apps have better end to end security than the phone system. The telcos could fix this if they wanted to. So far the pain doesn't seem to be bad enough.
I always cringe when I hear of criminal cases or disciplinary action initiated based on CID.