Another forum I'm a member of, a guy got the caller's actual phone number out of them, saying he was busy and would call back. He called back enough times that
they blocked
him.
Another guy gave them a credit card number. When they pointed out that it had one too many digits, he explained that that is how the numbers are, with the Bank of Nigeria.
At our house, we have a phone that requires one to press "1" to continue. Robocall hasn't that feature yet. The phone doesn't even ring if they don't press 1. It's a lot quieter around here, now.