another  IRS scammer.    Don't pay these people, block them, ignore them.   They are NOT the IRS.   The IRS doesn't initiate cases this way.  You get letters.  Then you need to verify the number to call back (like look in your 1040 instructions) and then deal with them.
I had to put call type as unknown, because 800notes doesn't give scam as an option, but the call is a scam.