Same thing happened to me yesterday! I called the number back and when a foreign man told me he was with the IRS and asked for my name and DOB I hung up! Scam!!!
Didn't recognize the number or ID so I let it go to voicemail. It was a long thing about tax fraud and I better call them back before charges are filed against me. The voice was disguised (robo-voice). I may report this to authorities as well because it impersonated the government and was threatening, but not sure how much good that will do.