They leave the following message which I find amusing:
"This is officer Daniel Wiseman calling you from the Legal Department of internal revenue services. This is in reference to a criminal lawsuit filed against you. Your case number is CF93271. The moment you receive this message I need you to return the call. The issue at hand is extremely time sensitive. The hotline to my desk is 202-787-1569. I repeat 202-787-1569. Don't disregard this message do return the call. Now if you don't return the call and I don't hear from your attorney either then the only thing I can do is wish you a good luck as the situation unfolds on you. Goodbye."
"as the situation unfolds on you" ... LOL! Can you say "English is not my first language"?
I like to call back and go over their grammar mistakes before I let them say anything. Then if they're still on the line I pretend to be a pollster and ask them who they are voting for this November!