I too just got this call.  The original PH# was 614-266-5548, the name listed was Bacchas, Andrea and she said she was from IRS and was ready to sue and listed a case #.  When I called the original PH# back, it was a private answering machine of a different male person (I did not catch a name).  I just phoned by tax guy to confirm this is BS.  But I suspect it is.   I don't believe the IRS calls like this.  They send snail mail.    Peace to you all.