If you are an Xfinity Mobile customer, you can manage blocked callers directly through your smartphone settings or the Xfinity app. Using Device Settings
Visit the Nomorobo website and select Xfinity as your carrier. xfinity block number
Xfinity Mobile includes a free feature called Spam Detection. You can enhance this by downloading the Xfinity app to: Enable "Silence Unknown Callers" (via device settings). If you are an Xfinity Mobile customer, you
The most immediate way to stop a specific number from reaching you is through your phone's native interface. xfinity block number
Here’s a clear, helpful write-up on how to block a number with Xfinity Voice (home phone) and Xfinity Mobile.