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.
Yes, but that requires you and the one(s) you’re communicating with to mod some radios and then to keep those radios secret, which won’t be easy once you start using them, especially in a situation like that where the government would probably be scanning those frequencies for exactly that