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.
Briar or meshtastic
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.
This was a common thing that was developed for the international protests after Arab Spring, which would frequently have their Internet shut down as a State tactic to prevent communication amongst protestors.
Mesh net chat apps like FireChat were born in response
https://en.m.wikipedia.org/wiki/FireChat
Edit: apparently wikipedia says it wasn’t developed for protests, it just happened to be released at the same time
It’s not p2p but at least many years ago:
SMS.
If the Internet outage is local then the towers would still work and you’d be able to get texts. I went through a few storms where wired home internet was down, the towers weren’t giving me a data connection (no mobile web browsing or anything), but I was able to send and receive texts.
If you really care about what you’re asking after, do what someone else said and get a radio license. It’s 150 year old technology and every time something happens radio operators pop up some kind of emergency communications or bridge to the internet through repeaters or something.
yggmail is a fairly obscure and experimental take on email on a mesh network: https://github.com/neilalexander/yggmail
yggmail specifically, probably not. yggdrasil uses TCP/IP and the Meshtastic latencies to perform connections would be too high AFAIK. It would probably only work in a fairly well-connected network. yggdrasil could be used directly over a WiFi protocol but it would need fairly good reception to function.
N.B. I haven’texperimented with this myself.