As reported by concerned Senior Citizen from the 805 area code, located in Ventura, CA: Caller left two messages, claimed to be from the IRS, alerting Subject of impending lawsuit regarding unpaid taxes.
Called once and left a message saying that the IRS had filed a law suite against me. For more details asked me to call them back. If this was the IRS they would not have called until after they sent out something in the mail.
When I attempted to call them back the phone just rang and rang. So this is definitely a scam, the IRS would have an automated answering system. Do not provide any details or personal information if this number calls you.