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?
First of all I just want to say that I completely agree with all of the technical things you talked about in his question but I think you kind of miss his question.
OP doesn't wanna be on SS7 (the thing that gives you your phone number), neither do I. I've just come to the conclusion that when it comes to infrastructure and paying for your goods SS7 is the only realistic option I have.
There is no distributed communication network anyone can just connect to. And the dream of leaving WiFi access points open for free (or for some kinda crypto-pay, e.g SkyNet) is just a dream, individuals have to invest in it and nobody wants to or take responsibility for it.
Here are some rules:
If we can come with a solution that fits these rules we can do away with the SS7 cellular protocol and have a truly anonymous network.
Yeah I would also want that but a radio network without sector and base station sectioning but it is unfeasible. Frequency spectrum is limited and scarce, sectoring is used in order to share the same frequencies between neighboring base stations. Thus a rough positioning is intrinsic on the system.
Completely anonymous radio link requires a unique radio " address " for each terminal. This is not possible because you need multiple base stations in order to cover big areas, thus you need multiple limited frequencies.
WiFi is a good example. It's concept is very similar to cellular networks but in small scale (well or it was designed for small scale). WiFi access points suppose they have a more or less clear frequency (from other WiFi stations), with that in consideration they can search for any device that responds for a given address.
But notice that in the modern days new WiFi standards have come up. This is because now we have tons of WiFi AP per building, per house, the freq band is limited too. Modern WiFi implementations are copying the cellular designs with OFDMA. They are starting to use sectoring and MIMO techniques in order to separate the WiFi coverage in sectors.
From a telecommunications point of view cellular networks are better and more efficient that legacy WiFi implementations.
The problem is that because of this some knowledge about the positioning of the terminal can be known. But so do it with modern WiFi.
Again the problem is not the technology but how we use it. Do we have laws that respect user privacy? Nowadays you can geolocate someone by their IP because most ISP nodes are gelocated in order to map network shortages.
Tracking does not depend on you after all. Any station to which you are connected knows you are near them and since most stations.know where they are they also rougly know where are you.
The problem resides in the way we protect our data. Should users be linked to terminals? Well always that you identify yourself from a terminal you are somehow telling that you ARE that terminal.
The problem here is trying to separate the user part from the rest. We must focus on techniques that allow a user to identify themselves in an a remote service without linking it to its real terminal. Tor does that in a way by separating layer by layer.
Is a complex deal. Just be aware of this issues and try to not be fooled by the WiFi VoIP is the new thing super mega privacy. Because when you think you are safe is when you get stabbed in the back.