This is a scam.

Scam phone call at 6:45 am. Says it's the IRS and they have a lawsuit against me. First of all, the IRS would not notify me of a lawsuit by a recorded message; they would send a letter by certified mail. Second, the IRS would start out with an audit, not a lawsuit. Third, I got this same phone call a month ago and ignored it. I called the number and there was no answer, probably because I blocked the Caller ID.

IRS Scam. Block

Recorded message said to to call this number IMMEDIATELY.  I didn't.

Recorded call claims that the IRS has filed a suit against me!
THIS IS FRAUD, pure and simple.
Our government does NOTHING about these calls.
Representing one self as an agent of the US government is against the law and the government is impotent.