Is Phone trackable without a SIM card?

treequell

peroxide7881 I am curious as to how this works when you have airplaine mode enabled but WiFi calling on so people can still call me. Assuming I am on my home wifi network or some other wifi network, would there still be any pings to cellular towers this way?

What do you mean by pinging? The WiFi call is still a regular phone call and is being routed through the cellular network, it just initially goes through the internet first. WiFi calling doesn't improve security or privacy.

peroxide7881

treequell thanks for sharing your insights.

Let me rephrase the question based on this, if you are on airplane mode but you have wifi calling on just so you can still be called when someone calls you, is this showing my IP to my ISP continuously then or only during a wifi call?

[deleted]

treequell can you please elaborate on that?

treequell

[deleted]

Wi-Fi calling works through transmitting the same cellular data packets as Wi-Fi VoIP through a Wi-Fi connection and across the internet. From the internet, data is passed to the cellular network and then back to the answering party. Wi-Fi calling must be supported by the smartphone to work.

https://www.techtarget.com/whatis/definition/Wi-Fi-calling#:~:text=Wi%2DFi%20calling%20works%20through%20transmitting%20the%20same%20cellular%20data%20packets%20as%20Wi%2DFi%20VoIP%20through%20a%20Wi%2DFi%20connection%20and%20across%20the%20internet.%20From%20the%20internet%2C%20data%20is%20passed%20to%20the%20cellular%20network%20and%20then%20back%20to%20the%20answering%20party.%20Wi%2DFi%20calling%20must%20be%20supported%20by%20the%20smartphone%20to%20work.

treequell

Enabling airplane mode would prevent cell tower triangulation, but WiFi calling reveals your IP address to your mobile carrier, and it can't be routed through the VPN tunnel on your device.

[deleted]

treequell the title says "without a sim card" so which mobile carrier?

Bismark

treequell
This is interesting. I can see the wifi calling connection in my router, but not using PCAPdroid app in fdroid. It must be becuase the way PCAPdroid works is by simulating a vpn hence wifi calling does not use it.

I think the only way to use a vpn with wifi calling is to have the router take care of the vpn, like selective routing.

treequell

[deleted] the title says "without a sim card" so which mobile carrier?

I see, thanks for that. I was addressing the question about how WiFi calling works.

It's not possible to make WiFi calls without a SIM card inserted or eSIM enabled.

[deleted]

peroxide7881 I think you didn't rephrase correctly.

If you mean the WiFi calling as @treequell understands it, with the sim card available I believe it would, but not when it's missing. Which carrier would it notify, albeit indirectly when the radio is supposed to be off in airplane mode?

You can still use a regular messenger like Whatsapp or Signal over WiFi with airplane mode (my understanding of WiFi calling) and that has nothing to do with cellular networks.

Which case is on your mind?

Carlos-Anso

peroxide7881
With phone in airplane, connected to wifi and wifi calling turned on your phone will be constantly connecting, via wifi, to the carrier of your SIM card so that they know where to route the calls.

peroxide7881

[deleted] well I am using a eSIM. So I do not know if that changes things. And if it is 'disabled' in the same sense as removing the SIM when u use a eSIM and it is on airplane mode with wifi calling on.

If it is indeed the case that my phone is constantly sending my real ip to my carrier with this setup I am curious how others deal with this? As unfortunately despite using signal and Whatsapp etc a lot of ppl where I work still rely on calling me by my normal phone number like a regular phone call.

So I have to be able to be called pretty much to do my job. But having airplane mode off and constantly connected to the normal cellular network is also a massive battery drain and I figured eSIM plus wifi calling plus airplane mode would be a bit private and save a lot of battery too. But of course as it seems thst may have been a wrong assumption from me.

[deleted]

traveller

traveller Is Pixel normally periodically pinging cell towers if SIM card is out/(or disabled) but the device is not in airplane mode?

Yes. Your phone pings towers for things like time updates (even without a SIM card).

other8026

[deleted] Your phone pings towers for things like time updates (even without a SIM card).

Here's a section of the website that explains how GrapheneOS handles updating time. In short, no, GrapheneOS doesn't ping cell towers for time updates.

An HTTPS connection is made to https://time.grapheneos.org/generate_204 to update the time with a millisecond precision X-Time header. As part of future support for using other services, it falls back to the standard Date header with second precision.

This is a full replacement for Android's standard network time update implementation, which uses unauthentication SNTP (Simple Network Time Protocol) with fallback to the cellular network when it's not available (GNSS can also be used as a time source but is disabled by default, and OEMs can choose the priority order). Network time updates are security sensitive since certificate validation depends on having an accurate time, but the standard NTP / SNTP protocols used across most OSes have no authentication or encryption.

From: https://grapheneos.org/faq#default-connections

traveller

other8026

So what else the cell towers can be contacted for when the SIM card is out? I'd think emergency services, but in this case the towers would need to be reached out to only when I explicitly dial the 112 number.

[deleted]

other8026 Interesting, so since it's an https connection, if you had no internet connectivity, it falls to the "standard date header with second precision? Is that a direct cellular tower connection (even without SIM)?

other8026

[deleted] I checked to be sure and that means that if the one header is missing, the OS will use the less precise time that's sent with the response (here's the part in the code where it does that).

For example, this is part of what I get when I use curl -v:

> GET /generate_204 HTTP/2
> Host: time.grapheneos.org
> User-Agent: curl/8.4.0
> Accept: */*
> 
* received GOAWAY, error=0, last_stream=1
< HTTP/2 204 
< server: nginx
< date: Wed, 27 Dec 2023 15:23:24 GMT
< strict-transport-security: max-age=63072000; includeSubDomains; preload
< x-robots-tag: none
< x-time: 1703690604109

There you can see a date header and an x-time header. Date is accurate to the second and the timestamp returned is accurate to the millisecond.

ryanwiltonkims

Yes, a phone can still be trackable even without a SIM card. While the SIM is what connects you to a carrier, the device itself can still connect through Wi-Fi or Bluetooth, and that data can be used to determine location. Also, most phones have a unique identifier (like an IMEI) that can be tracked if the device connects to certain networks. GPS works independently of the SIM as well, so location services can still function. It’s not as straightforward as tracking a phone with an active SIM, but it’s definitely possible depending on the situation.

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