That's true about the blocking as I don't think the TC can do wildcard blocking. However it doesn't need to do that. If a number isn't specifically blocked but isn't on the white list the caller is going to have to sit through ten seconds of spiel then say their name then wait for me to decide if I want to speak to them.
Our message:"Hi. We screen all incoming calls and we will not accept marketing calls nor calls from anyone we don't know. If you say your name after the beep we will decide whether or not we wish to accept your call."
The machine then says: "Please say your name after the tone."
It would take a particularly stupid and persistent person to listen to all that then choose to say "Acme Marketing Company" in the expectation of us actually choosing to speak to them. And the worst case scenario even if they are so stupid is that we listen to them saying "Acme Marketing Company" and put the phone down. I don't think I even have any blocked numbers programmed. There's never been any need. The message is off putting enough.
We often see the TC light up with an incoming call but after three or four seconds it goes dark again. Cold callers obviously aren't stupid