I think I found the same information you found. But I figured if it was IRS 1. The number would be easily identified (This number seems to have started being used recently and 2. It would be listed on their website.
https://www.irs.gov/uac/Tax-Scams-Consumer-Alerts
This is from their website:
If the phone isn't answered, the scammers often leave an “urgent” callback request.
Note that the IRS will never: 1) call to demand immediate payment, nor will the agency call about taxes owed without first having mailed you a bill; 2) demand that you pay taxes without giving you the opportunity to question or appeal the amount they say you owe; 3) require you to use a specific payment method for your taxes, such as a prepaid debit card; 4) ask for credit or debit card numbers over the phone; or 5) threaten to bring in local police or other law-enforcement groups to have you arrested for not paying.
Got 2 calls today. One at 11:30 and another at 4:25. Recorded messaqe says this is the IRS calling. Says this is my final notice. Unless I call 470-424-9650 they will file suit. Did not call. I know a SCAM when I hear one.
It is a scam,, they have been calling my friends mother non stop.. SHe called me scared and I checked into it and it is for a sure a scam… The IRS will send you a letter if there is any issue with you're taxes…