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Can you address a device over a cellular network by it's IMEI number? I didn't think you could. You'd need a phone number as well. Could well be different over 5G though.

The IMEI is permanently associated with the device.

The phone number (IMSI) is associated with the SIM card (or eSIM now) and can be trivially swapped out.

A network can definitely address a device by IMEI only. For example in most countries you can make emergency phone calls to 911/112 with no SIM card in your phone (and hence no phone number) and there are no troubles routing that call.

For 2G GSM the emergency calls are one big special case in the radio interface layer and do not really work as normal calls, this mechanism is triggered by dialing '112' which is hardcoded into the terminal (and does not work for other emergency service numbers, although US terminals maybe also special case 911, on European ones only 112 work).

IIRC BSC can page terminals on PCH not only by TMSI (which should be the normal state) but also by raw IMSI or IMEI, but this is not an capability that gets you anything useful as the terminal has to have active association to the network to even listen on PCH and when the device is associated the network knows the relationship between all of these three values.

The IMEI uniquely identifies the device; the IMSI uniquely identifies the subscriber.


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