Turning It On. As a Comcast phone subscriber, you can activate anonymous call rejection from your telephone. Pick up your receiver, or press Talk on a cordless phone, and wait until you hear a dial tone.Press *77 to turn the feature on. To deactivate it, press *87..urning It On. As a Comcast phone subscriber, you can activate anonymous call rejection from your telephone. Pick up your receiver, or press Talk on a cordless phone, and wait until you hear a dial tone.