It happened to me too, today. I do not owe any taxes to IRS. I just received my tax refund for 2016. The phone number was 240-330-6329.
They identified themselves as IRS investigating team. The Lady had a foreign accent too. They also stated they mailed me letters about the "delinquency" (I did not receive any), and that if I do not respond a warrant would be issued to the law enforcement, to have me arrested. And when I asked for details, they hanged up. Beware!
.
I got three missed call and a voicemail from this number this afternoon. The dude with strong indian accent stated my name and his name and saying there's a legal something filed against my property. I should call him as soon as I can before they push it to court.