A question for folks who know things I don't: if I wanted my phones to work in an area without cell signal, for just me and my family, is it possible to build a "personal" cell tower that our phones would just connect to and work, and allow us to text each other? Or is there a whole layer of auth required for our various phones to actually be able to use a fake network?
Yes. There is a way to setup a private cell using SDR. There was a talk about that in Chaos Computer Club some years ago. I do not remember how they did with the simcards, if they were custom, or normal out of service ones. Caution: because the spectrum band is licensed, it will be automatically illegal pretty much everywhere!
Here’s a recent post I found on open source software for that. I remember a recent post about folks using base stations that were popular with the Helium network to run their own stuff, but I can’t find it at the moment.
There are micro-towers for cell phone testing you can buy and cell phones think it's a real tower. Law enforcement uses one of them to track criminals IIRC.
VoWiFi requires an internet connection. It dials back to your carrier.
Nothing preventing you from configuring a local SIP server or doing IP-to-IP calls, though. I think every platorm imaginable has some kind of free SIP client.
Not really. This stuff is heavily NDA and patent encumbered. You’d be better off setting up a local wifi network and using an IP based audio call system.
I'm not sure if this applies to all carriers but with many carriers if you are on wifi you can send/receive text messages and sometimes even make calls. Certainly you could use WhatsApp or similar in that case.
