I got the same message and called the number back. After going back and forth with this woman (who had a heavy accent), I finally hung up on her after telling them I'd be waiting for them to come and get me.
Scam call from "IRS" threat of law suit. Called back, ESL, terrible accent, asking for personal information, told them you called me, you should have my information & to go ahead send the IRS after me and they hung up