If you can call it, it's an existing phone number, so in that sense it's real. But no doubt it's a scam, either designed to have you pay for nothing or for installing malware on your PC. Don't call.
If that popup comes from a site you visit: better don't visit that site anymore.
If that popup comes from a program installed on your computer: remove it by running the right antivirus or antilmalware program. If you don't know how, post again.
Kees
Recently, I keep getting a a popup that said there was a security issue and that he needed to call a number 1-888-447-4192 for Windows Firewall Service. Should I trust it? Is 1-888-447-4192 a genuine phone number?

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