Do Not Call Registry

I think the phone company and our federal government's Do Not Call registry (https://donotcall.gov) are letting us down.

The cell phone network is a closed system, which gives the phone companies complete control over who accesses it; so, I'm thinking that it wouldn't be too hard to block calls displaying a caller ID from a disconnected/out of service phone number in the same way that Gmail blocks or filters spam. 🤔