Got the same robo call. Called the number back. Clearly it's a call center and they refused to give me their name. So, I said "I'm An IRS Agent" and I need to speak to your supervisor. They hung up. I am going to have A LOT of FUN with this phone number. You can, too. Just block your number before you call. Hey, maybe we can collectively get back at these scammers !
This is the message that was left on voice mail. "IRS has an arrest warrant against you right now you and your physical property. Those are being monitored and it's very important that I do hear back from you as soon as possible before we proceed further any legal matter. My direct call back number is (206) 629-6004. Again the number is (206) 629-6004. Thank you."