CID showed Unknown, so I let the answering machine take it. They didn't actually leave a message, but stayed on the line, so the machine recorded boilerroom/call center back ground noise. Scammers.
I have been getting calls at least once a day. Sometimes repeatedly within an hour; never leaves a message. I tried calling back and said it was a landline and couldn't leave a message. Tried again and a guy answered. Accent and kinda creepy. So hung up.
That number calls everyday, one time a guy with an horrible accent called and said, he wants to set us up with an government contract, I hung up, most of the time there is nobody on the other line.