Well, I no longer have a land line in lieu of cell phones, but I had a great caller ID box that I could either select #'s to block or have it not accept "blocked" or private calls. The callers would get a friendly voice that said "the party you reached is not accepting your calls at this time" or "the party you reached does not accept anonymous calls, please disable your call blocking feature and try again" then it would promptly hang up on them. It was an awesome caller ID unit.