This is definitely a scam... I also have received a number of calls claiming to be from the IRS or a Federal agency. This is today's voice mail: "This is the final attempt to reach you to resolve this issue immediately and to speak to a Federal agent the department call back number is 301-223-3005. I repeat 301-223-3005. Thank you."
i tried the number, some [***] answers "IRS Criminal Division how can i help you"
then i called IRS hotline and turned them in
told the nice lady "Surely your friends in NSA can track down where the call goes to"
For every response published here, at least ten times as many abusive calls received daily. So very sad that the FCC, FBI, NSA or some federal agency does not care enough to follow up on the source of these impersonations. Are you listening IRS, SCOTUS? HELLO?????