I find that doctors offices often call from an unknown number. This is for privacy reasons: if a psych doctor calls and someone who doesn't know I am seeing one

I find that doctors offices often call from an unknown number. This is for privacy reasons: if a psych doctor calls and someone who doesn't know I am seeing one sees the caller ID, they would have violated my privacy. Also as a rule they don't leave voice mail messages beyond "this is Dr. So-and-so please call me back." Because of this I always answer all unknown numbers. If they turn out to be a telemarketer, I tell them they called the director of the FBI and ask them who they work for and how they got my number, then promise them to investigate their company because calling this secure line is a threat to national security.