Cell service on grapheneos

tpain8300

so I've been using my grapheneos phone on airplane mode since I got it, but I need to get some type of mobile service. I've looked at services like silent link but my question is, since I know that emergency services and cell towers still connect even when you have no sim, will other service companies/cell tower companies/government or anyone other than silent.link have access to my IMEI along with my location when I turn off airplane mode? Or only the carrier that I use. I am trying to minimize location tracking data that is associated with my identity, and if say At&t for example could still see my imei and location, they could connect it with my home location associated with devices in my name. Thanks for the help

de0u

tpain8300 Every cell site your phone contacts will receive your IMEI and IMSI (source).

tpain8300

de0u So at&t can track my imei along with exact location through triangulation even if I am using silent link

rellhom

de0u

so even if you never put a sim card in your phone you are still being tracked by your imei? is there no way that GOS can turn this off?

DeletedUser69

tpain8300 they can track a location of an unknown identity if you can remain anonymous which is very hard.

r134a

DeletedUser69 Also, i could be wrong here, but i assume triangulation is not something that occurs 'automatically'. I think some sort of operator intervention is necessary to actually perform a triangulation, but again i'm not sure of this.

tpain8300 i don't have any experience with at&t & silent link, but in europe for example if u use one operator, it doesn't mean u will never use another tower of that of your operator. For example many smaller operator's don't actually own towers and 'rent' towers of bigger operators. There could also be an agreement between bigger operators to 'lend' their towers to eachother.

de0u

tpain8300 So at&t can track my imei along with exact location through triangulation even if I am using silent link

That is more or less correct. The "exact location" and "triangulation" parts are a little fuzzy, but more accurate than inaccurate.

Cellular networks are inherently designed to be tracking networks. In many countries cellular carriers are legally required to provide fast and specific location information for emergency calls and/or law enforcement purposes. A SIM vendor can't magically undo how the network was designed to operate.

My understanding is that silent.link can provide users with some privacy with respect to called/calling parties, apps, etc., and probably can provide a minor "speed bump" if government wants to map to an identity. In the other direction, using a privacy-focused SIM card may attract extra scrutiny, since probably you are the only person in your area using one.

Cellular networks are designed to track their users (including roaming users, not just their direct customers).

DeletedUser69

r134a I said they can, not that they do. But and this is a pure speculation, if they can't link user to a real world identity, it makes the target more suspicious a worth following.

r134a

DeletedUser69 i don't said u said they do, it was just a supplement to your answer.

To rectify my speculation about triangulation not happening automatically, it seems it actually does happen automatically. When connected to a cell tower your device still sends out probe requests to nearby cell towers. One of the reasons triangulation is performed automatically is 'handovers'. If u move around and the tower you are intially connected to, can't provide a 'stable' connection anymore, it will be 'handover' to the nearest tower of location at that time.

r134a

Interesting read regarding this topic which isn't to bloated: https://www.linkedin.com/pulse/cellular-networks-triangulation-methods-understanding-kanajam-rqgnc

Probably9857

rellhom

Airplane mode

rellhom

Probably9857

I forget if airplane mode can allow wifi or not if you want. What if you want your phone to never ever broadcast to cell towers, but you want to use wifi as needed (turning it on and off as needed)?

Probably9857

rellhom
WiFi works just fine in Airplane mode. It's off by default, but you can turn it on, and the OS will remember that preference.

de0u

rellhom I forget if airplane mode can allow wifi or not if you want. What if you want your phone to never ever broadcast to cell towers, but you want to use wifi as needed (turning it on and off as needed)?

Airplane mode turns the cellular modem off. It may well turn Wi-Fi off too, but you can turn it back on if you want, and the cellular modem will remain off.

It might be a good idea to periodically re-read:

Over time as one uses more features, parts of those documents that were previously irrelevant can become relevant.

rellhom

thanks for the answers, I'm guessing most don't realize that turning the brand new phone on for the first time was enough to have your imei location recorded on an AT&T database etc. though

de0u

rellhom I'm guessing most don't realize that turning the brand new phone on for the first time was enough to have your imei location recorded on an AT&T database etc. though

I suspect you're right.

I also suspect a large fraction of GrapheneOS users have a regular SIM card, have airplane mode off almost all the time, and make and receive regular phone calls. Obviously I have no actual data, but we do get lots of posts on the forum about regular cellular calls (especially when Google ships a glitchy telephony stack), call recording, SMS apps, etc. I think a lot of GrapheneOS users are looking to conceal their data and their behavior from Google and Meta, etc., and are satisfied if they can do that.

So I suspect many GrapheneOS users don't know that powering the phone on the first time may associate their hardware with their home address, but I also suspect it makes no difference for many, because the first step after installing GrapheneOS will be popping in a SIM card and calling a friend to make sure it works.

DeletedUser76

What if Airplane mode is automatically turned on after the first boot/factory reset? Won't that remove the possibility of an actor using triangulation to associate an address to the phone? For example, one could just set up the device in airplane mode, and use it in airplane mode forever, while turning on the Wifi only when needed.

DeletedUser69

DeletedUser76 unfortunately after every reboot airplane mode isn't automatically activated even in BFU, baseband is active and by the time you unlock the device to put it in airplane mode your radio likely already broadcasts your imei to all cell towers in the area.

de0u

DeletedUser69 unfortunately after every reboot airplane mode isn't automatically activated even in BFU

Can you provide a detailed list of steps to reproduce this, maybe along the lines of:

Enable airplane mode,
Tap power button to lock screen,
Tap power button again to light screen, verify that "airplane mode" is displayed,
Press and hold power button until menu pops up,
Choose "Restart",
When the system finishes booting, the lock-screen display does/does-not show "airplane mode" and does/does-not show carrier info.

If rebooting disables airplane mode for you, can you report the device type and build number? Is Wi-Fi calling on or off?

DeletedUser69

de0u apologies, I spoke too soon. I have now simulated disabling mobile network/ turning WiFi off, turning on aeroplane mode and that stays on after restart. Thanks for pointing me in the right direction.

So if one wants to use their device in aeroplane mode only, they should when they first turn it on, do it in the area that is not their home and/or area with no network (like a basement) which can be verified by using another device (being outside coverage).