The "IRS Scam." Called twice, left a recorded message, claimed that an urgent reply to this number is necessary to avoid "immediate action." Requested a call from whoever (since they gave no name) or "your attorney of record." I was tempted to call back and ream them as I am an attorney myself but decided to complain to the FCC instead. No need to give them access to my personal life in any way.
I got two messages on our answering machine saying it was urgent to contact them back or they would take immediate action. When you call the number back it just rang and then cut off. I am assuming from the other comments I see here that this is some kind of a scam so I won't worry about it or attempt to call the number back again.