That's true, but the strange thing is it has hardly evolved from that. Why does not my phone operator allow me to set policies / firewalls in place, at their end? All such filtering now needs to happen in my actual phone.
What's wrong with filtering in your phone? It's a much simpler solution, and has the advantage that your contact list doesn't need to be stored in a central location where it is freely available to employees, law enforcement, and hackers.
What would the UI to the PBXes look like? Back in the 80s, what limited programming we could do was done by pressing numbers and the asterisk/pound key. Sometimes "flashing" the hook. If we're lucky, voice prompts. It was crap.
So you want to add some sort of digital protocol between phones and PBXes (of countless different types) so that our contact lists and rules (like "don't ring for these numbers between 10pm and 8am") can be maintained by an insecure central authority?
I think the technology branch we're on is better. It's certainly more personally empowering.
