This works on most Comcast digital voice lines:
Xfinity allows you to block up to 25 numbers using this method. If the list is full, you must delete a number to add a new one. You can also dial *80 to turn off Call Blocking or unblock numbers. how to block a number on a landline comcast
If you manage your landline through the Xfinity Connect app on your smartphone: This works on most Comcast digital voice lines:
For a more visual approach, you can manage your "Blacklist" through your online account. This is often easier than using the phone keypad for long lists. Log in to your Xfinity account at xfinity.com. Navigate to the "Voice" or "Phone" section. Click on "Settings" (the gear icon). Select "Call Blocking" or "Screening." Enter the numbers you wish to block and save your changes. Enable "Nomorobo" for Robocalls If you manage your landline through the Xfinity
While not a technical "block," registering your Comcast landline with the government can legally reduce the number of telemarketing calls you receive. Visit donotcall.gov. Register your landline number.
Listen for a confirmation tone or message indicating the service is active. To deactivate this feature later, simply dial *87. Block Specific Numbers with Call Screening
It takes about 31 days for the registry to take full effect.