That makes it easy then. The IRS does not call you on tax issues without sending a mail or a bill first, much less likely so on weekends. There is not even an IRS office at the location where the number is associated.
Unidentifiable "Dell Support " called to tell me that "half the processes" on windows had stopped working. Never mind that I use mac. Never mind that I run a firewall. Never mind that I would never allow any of my computers to send detailed process info to the manufacturer.