It is a hoax. The IRS will send a certified letter in the mail regarding any pending action. You will never receive a phone call of that nature from the IRS.
I have received several calls with a voice message stating they are from the IRS and that I am being sued. when I called back I asked the man who has a very strong accent for his IRS ID # and he hangs up. they are also now calling from a different # in Texas 281-608-6460.
Claims to be IRS. Multiple calls different days. First from 423 920-0571 then from 281-608-6460. The the man, who has a very strong accent, answered at both numbers. Reported the numbers to Treasury Inspector General for Tax Administration.