Perhaps this has been going on for a while but it is the first I have had it happen to me. Over the last two days I have had robocalls from two numbers - 626-265-4560 and 413-356-4173. The robot says in a menacing way that this is the final call I am going to get and that the IRS is about to file a lawsuit against me. I knew better than to believe this and did not call back, but several websites report that if you call these numbers, you get an operator who demands personal information without giving out any explanation. Beware. This is obvious phishing and should be avoided.
Update: Add 213-447-4831 and 802-673-0582 to the list.