I received the same message just now! I got nervous at first, but glad to read that this is just a scam. That's why I never answer calls from a number I do not recognize.
ROFL.... Supposedly a call from IRS: Their Message (as interpreted by my phone's voice to text service): Hello we have been trying to reach you. This call is officially an final notice from IRS Internal Revenue Service. The reason of this call is to inform you that IRS is filing a lawsuit against you to get more information about this case file. Please call immediately on our department number 646-630-9985. I repeat the number 646-630-9985. Thank you.