I do it by not answering my phone unless I recognize the number. If it's important, callers will leave a message. If it's important to me, I'll return it. And it has the entertainment value of watching visitors get nervous when I ignore the phone!
Hi 99corvette -- You can speak with our Security Assurance team for tips on how to prevent or manage fraud/scam calls and emails. You can reach them at 1-888-565-4329.
You can also learn more about protecting yourself from email phishing here: https://www.xfinity.com/support/articles/phishing-scams and phone scams here: https://www.xfinity.com/support/articles/protect-yourself-phone-scams.