I agree. There could be a lot of improvements that can be done to telephone. Of course, they might have tradeoffs (privacy vs. convenience). That's where providing multiple options to the user comes handy.

Some of the improvements (just top of my mind): crowd-sourced list of scammers, telemarketers. For outgoing calls: automapping phone numbers to business/user names, automatically using the best way to route the call based on call rates (WiFi vs cellular vs. multipath TCP) etc.