Lame! My wife's AT&T phone connection is having real issues today. Now, she's locked out of texting and calling. We need a Nostr replacement for talk.
I think a system that uses Nostr to perform a handshake, starting with a request to talk event, an accept event, then the two devices negotiate a VoIP route to conclude the handshake.
What you are describing already exists mostly. The SIP protocol does exactly that. The only thing missing is that SIP uses email or phone number as ID.
With a modification to use NIP-05 or npub, 2 SIP clients could perform a VoIP call.
XMPP
then you just need a XMPP registry that gives out addresses of the form npub@website and requires the nsec to register
Bitcoin phone
