Left a msg stating this was the IRS and this was a final attempt to collect. I called back a heavy accented male answered IRS. I asked where he was located and received no answer for 5-7 seconds ( could hear others in background). So I asked "is this a scam?" He responded "Yeah, what are gonna do about it?"
Same story as others... After receiving THREE calls from them today, I called them back and asked them to remove me from their calling list. They said "OK, thank you" and hung up. (I'm sure I'll hear from the again!)