The voice sounded robotic; might be artificial. Said she was Heather "Gray?" from the IRS and I do not recall the location that the caller ID noted for the phone's source. Same thing, call right away or something dire happens, presumably.
Call them back and play some porn very loundly over the speaker to them. These foriegn idiots will lisen to it for hours and not bother our elderly, which is their primary target and the onse most likely to give them the info they need to scam money