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 !
The message that was left on voice mail is: "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."