Rec'd call from James Caspin (?), heavy accent. Said if I failed to return call, I wold have to appear before a mistriate, calling from US Treasury. And an warrant would be issued if no action was taken. Since I know they don't call demanding payment over the phone, it's a scam and will not be calling back.
Get on their nerves even more by not answering unknown numbers in any way at all. Here they're thinking up (awful job of it) ways to scare you into paying a bogus debt and you'll return their call. Suddenly they're not even able to leave messages when they call, good way to get them mad.