eSIM and physical SIM correlation

indigomadelin

Hi everyone. I'm about to use an eSIM for the first time. Device has two SIM adapters: a physical SIM (IMEI 1234) and an eSIM (IMEI 6789). Does the eSIM support toggle function similarly to airplane mode? Specifically, when eSIM support is disabled, how many IMEIs are visible to cell towers? I want to avoid correlation between my physical SIM and eSIM, so I'm wondering if enabling/disabling eSIM support at different times than the physical SIM might reduce the likelihood that surveillance systems detect they belong to the same device.

23Sha-ger

Yes, however there are few things to note:
When you really want them to be isolated, you have to disable DSDS (dual sim dual standby) in
the *#*#4636#*#* phone information menu. Otherwise your other IMEI will still broadcast.

While the IMEIs are different from a carrier point of view, they still share the same TAC.
An IMSI catcher can detect that the same device model was present in a specific area.
So a capable adversary can still geo-fence devices based on that, but that requires serious active
investigation to take place. Namely, which "Pixel 8" was present in location X at DDMMYY:HHMM.

This is a theoretical correlation but it exists. But I can name only a few countries capable of that.

dawt

23Sha-ger Otherwise your other IMEI will still broadcast.

Source?

Also, all this worry about how many IMEIs are broadcast matter because pixels (at least the older ones) use sequential IMEIs, so it's very easy to infer that two IMEIs are the same phone, or what the other IMEI of a phone is.

23Sha-ger

dawt Source?

This is common knowledge with many sources. This is why airplane mode is the only way to prevent your
baseband from interacting with cell towers. This is why you can make an emergency call without a SIM.
https://security.stackexchange.com/questions/201028/can-a-sim-less-smartphone-be-tracked-only-by-imei

dawt

23Sha-ger

That's not the same as both IMEIs being broadcast, though. It makes sense for the cellphone to maintain one connection for emergency purposes, but not to maintain two connections. The second one doesn't do anything and just drains the battery more.