We get scammers calling us on our TT landline number where their number appears to be valid, but when checked it turns out to be inaccessible. For instance today we got a call from 01273065322 which is a Brighton area number. Because we have friends and relatives in Brighton we answered it and the caller claimed to be from BTOpenreach saying we have problems with out internet speed. I terminated the call immediately. Dialled the number prefixed by 141 but got a message stating it was invalid.
But this raised a question in my mind as to why BT (or TT?) can't check the calling number and block the call if it's invalid before connecting the call?
I know we could use CallSafe but what I'm suggesting could stop many scam calls at source.