Didn't answer, since I didn't recognize the number. Best policy; that is what voice mailboxes are for. If it's important and they have actual business with me, they can leave a message. Thanks to everyone here for reporting them.
I really wish the government would quantify how much of our time is wasted talking to these scammers who definitely are not contributing to the economy, because they don't pay taxes on their ill-gotten gains. At the least, excepting a few agencies and people who have reason to hide their numbers (e.g., law enforcement and those who have obtained court protection orders against others), we should be able to see the identity of the calling party along with the number, without paying for special caller ID services.