It's an "IRS scam". They tell you that this is the second attempt to contact you and that you must call back immediately to avoid further penalties. (Report the number. Block the caller. Delete the message. And get on with your day.)
Got a threatening call from someone in Seattle WA claiming to be the IRS. I'm a former Tax preparer & member of the CTEC. I smelled a rat because 1) The robot call Identified it's self as a Federal Agent for the IRS but didn't say who he was trying to contact 2) IRS always notifies you by mail if there's a problem with your tax return forms 3) The IRS never threatens Tax Payers unless they're sure some kind of fraud is involved. Don't return this call. Report it to the TIGTA at https://www.treasury.gov/tigta/contact_report.shtml