I just got a call from this phone number, left a message on my voice mail. The automatic voice informed me about IRS open case against me and this is the last chance to stop it. Clearly it is a scam. Don't pay attention and block this phone number. Two years ago I went to a real IRS investigation, and IRS always notified you the open a case by letter, no by phone call.
Message indicated that it was the last attempt to contact me that the IRS had filed lawsuit against me. Called the same # back and foreign gentlman answred call as Internal Revenue Service - wanting me to confirm my identify / home address. When I wouldn't he indicated my name (first name only, which was correct) and said the IRS had issued an arrest warrant against me