This is something I’ve been thinking about for a while. I’ve decided to get a Pixel with GrapheneOS as my next phone and I’m trying to decide the pros and cons of putting a SIM card in it. Convenience vs privacy, public wifi with a VPN vs using phone data, etc.
I can’t get a SIM card where I live without ID and I’m looking to reduce being tracked as much as possible. Does anyone else do the same thing?
Yes, the cell tower can see the unique IMEI of your phone, so as long as the cell radio is on, the cell company can at least see what tower that IMEI is in range of. And if they can track the purchase of the phone to you, then they can identify your signal.
That isn’t entirely true. While a phone without a SIM can still listen to broadcasts, it never registers as a subscriber because It’s missing a IMSI. So no, without a SIM you are indeed invisible to carriers. It’s a bit like screaming into the woods - someone might hear you if you do that, but if he doesn’t scream back, you have no idea he’s there.
The only exception to this if you’re actively calling emergency services - in that case, your phone will attempt an emergency attach to any network it can find, which is the point where the carrier of that network could see your IMEI. However, apart from that, you are indeed completely invisible without a SIM card.