I just got this call and they were threatening to have me arrested if I didn't pay $4985! When I asked why their phone number was showing up online as an IRS scam they said they didn't know what I was talking about.
I also got a call on my landline recorder today from 360-515-7848 with the same verbage: IRS final notice-we are initiating a lawsuit. I am a retired IRS agent, so can confirm this is 99.999% a phishing attempt. DO NOT GIVE THESE PEOPLE ANY INFO! See Slim's IRS-Tigta number above (below?) to report this. PS: Several years ago, IRS examiners were encouraged to call for a field appointment, prior to sending a letter/audit notice. I am not sure this is still applicable, but you should just request that the IRS notice (form) letter be sent to you. See: http://www.irs.gov/Individuals/Understanding-Your-IRS-Notice-or-Letter.
Received a voice mail message in a computer generated voice that today was my last day to contact the IRS before they file a lawsuit against me. Seemed scary, but I don't think the IRS files lawsuits. Glad to learn this isn't real;)