Indeed. Using self-descriptive "handles" or usernames such as @name.surname or @company.city would be great for caller and texter identification, as well as user discovery--if they want it to be public, that is. That, and having to send a request before you can contact anyone would bring some control and protection back to the user.

Incidentally, this is already possible with SIP, which is behind most standardised VoIP signalling. In particular it allows for federation too.

if we're going to reinvent PSTN, can we also include in that specification an arbitrary length numeric passcode that a number owner can set, and reset, to require for the call to ring through, or even return the SIT if the passcode fails?

How would international calls work?

The same way website addresses work, DNS type of thing?