If I use GrapheneOS with a SIM, will my data be eavesdropped on?

miyakore

Sorry for posting every day. I apologize if I'm making assumptions. I'm a Japanese woman and not very knowledgeable about IT.

I mainly use GrapheneOS on Wi-Fi, but for calls I'd like to use the original GrapheneOS calling app instead of the calling app.

I've heard that a physical SIM card will allow you to know my location,

but unless the other party is also using GrapheneOS, will my calls be eavesdropped on?

*I'm a victim of cyberstalking.

However, I'm not an expert enough to obtain data evidence of hackers.

miyakore

I'm using the translation function. I'm sorry if it's wrong. I'm a beginner.

Vincent96

If you use a mobile network at all your location can be triangulated. It doesn't matter if you use a SIM or eSIM.

Traditional phone calls are not secure. Use Signal or an encrypted calling app instead of using phone calls for secure communication.

miyakore

So even a physical SIM card can be used to contact my company,
but it seems like it's difficult to use Signal or similar.
Will it be possible to be identified even if you're away for a short time, like when you have a cold and want to take a day off?

DohnJoe

miyakore Will it be possible to be identified even if you're away for a short time, like when you have a cold and want to take a day off?

Realistically speaking, unless your smartphone comes from your company or you have some corporate app installed, they have little ways to have your location info.
The triangulation you read about your SIM (or eSIM) is done by your provider and it is needed by design for phone and SMSs to work.

So you should be fine, unless one of this is true:

You have a smartphone set up by your company;
You installed an app from your company;
Your company is also your provider;
Your company can have provider's information somehow.

Of course, GOS cannot help you if you make bad use of it, like posting a picture of yourself at the mall during sick days.

For the rest, if you have bluetooth off, wireless off (also in geolocation settings), nfc off, etc., will be very difficult for an external agent to track your position (except your provider).

If you want to be more than sure, keep airplane mode on while you roam, or leave if you don't need it, leave your smartphone at home.

miyakore

DohnJoe
Thank you. I'll try using it that way.

DohnJoe

miyakore

Just because of the title, I would like to add that if you have to make a phone call, it is strongly suggested to disable 2g and 3g networks entirely, (just few taps in Settings).

I would also enable VoWIFI or VoLTE.