We all know Signal, Matrix, Telegram, SimpleX, etc… But if you can’t access the internet you can’t communicate. Pretty logic. But would it be possible, at least theoretically, to create an app that permits to message people even if the internet goes down?
It might be a dumb question I really have no idea to be honest.
Telegram isn’t P2P and isn’t recommended. Signal is good, but not P2P. Matrix is decentralized, not P2P. SimpleX is P2P, I think, but not sure.
SimpleX uses onion links
Simplex uses Severs, you can bring your own one, but it is not peer to peer when talking about direct communication to the recipient