I'm investigating getting off the cell network permanently to avoid at least the constant triangulation of my position. I figured I'd look into getting a VoIP number and getting calls and texts over WiFi. I don't mind being unreachable when I'm not connected to a hotspot, so it's not a problem for me.
But before looking for a good VoIP provider, I decided to check if WiFi still worked in airplane mode. And indeed it works. But to my surprise, when I connected the WiFi, my cellphone provider's name also came right back up at the top right of the screen. In airplane mode? What the hell?
Long story short, after investigating a bit, I realized I had WiFi calling enabled. So I can in fact already get calls and texts without being on the cell network.
And I'm thinking, maybe that's good enough for privacy?
I mean I know SIMs leak information like ICCID / IMSI / IMEI so obviously they have no reason not to do that over WiFi also and that's not so hot.
But on the plus side, none of that information is linked to cell towers and location anymore - at least not precise location if I'm not on a VPN - the baseband processor is off and can't do whatever shady chit-chat it does with the SIM and the cell towers, and I can still use my normal phone numbers without having to change and tell a million people that I have new numbers if I go with VoIP.
Also, I don't store my contacts on my SIMs and I use a deGoogled Android. So I figure that limits how much adversarial software can exploit the SIMs to leak data.
So it seems to me that WiFi calling may be a good solution for me for better privacy without too many compromises.
Can you think of something I missed that I should know before using this feature?
Maybe?
Afaik wifi calling works the same as VoLTE, which afaik is just VoIP, but handled by your mobile provider, and integrated into your normal mobile plan, so it works with your phone number.
When both ends of a call have the service, the call is entirely VoIP, which is how it achieves the much nicer audio quality for these calls.
If you just completely disable the mobile radios (set your phone not to use any kind of connection from the sim settings, while still enabling the sim) and use wifi exclusively, then it should work as if you just have VoIP service?
Well, I know it's all going through the internet anyway nowadays, so yeah it's technically always voice-over-IP even if I use the cell network. The only difference between normal calls and WiFi calls is how it connects to the internet really. I just don't want the extra baggage that comes with staying connected to the cell netowk method of getting on the internet.
And of course what I referred to when I said VoIP is pure VoIP providers that sell you a number and access to a SIP server, independent from your cellphone provider.
It's not. GSM calls are definitely still a thing, and while VoLTE is becoming more and more common, it's not universal.