Seems to me SPAM or similar

From Wash. DC exchange-accent voice. IRS problem. Total scam.  Ignore and block number.  Don't be fooled.

Pretending to be an AARP Rep left threatening message indicating that not returning the call will be considered intentional avoidance of appearing before a magistrate for a federally criminal offense.

You are absolutely correct! This is a scam that is going around now.  The IRS would never call or email you; they would only contact you by mail.  The caller ID showed up as AARP with phone # 202-215-5408. The guy with an overseas accent left a voice message and was so stupid to twice repeat the phone number to call him back as 201, not 202...!

Ditto. Called 1.5 hrs ago. No caller ID shown. But message left same as described by KF.