For others reading this thread...
(See our full thread covering this topic: https://grapheneos.social/@GrapheneOS/113319956422621755)
Connect to a cellular network ➔ SIM identifies your subscription via IMSI ➔ radio identifies itself via IMEI (as well as other ID's.)
hmop the imsi simply talks to the network
IMSI is the identifier of your SIM card (your subscriber ID).
IMSI is not hard-wired in the phone and you can get a new IMSI by putting in a different SIM card.
It's tied to your phone plan and there is no limitation on changing IMSI.
The telecoms network needs your IMSI or you can't access the network.
hmop the imei identifies the phone
make model owner
IMEI is a hardware identifier.
The cellular radio has multiple IMEIs (radio identifiers) that are part of the SoC and/or a separate radio, which would depend on the device. An IMEI by the standards is not supposed to be changeable. The reason it is not supported is because modern radios don't support (by the hardware/firmware) changing IMEI.
hmop SAME CELL NUMBER $5000
@hmop Citation needed ^.
IMEI is not the only hardware identifier for the device available to the cellular network. Changing the IMEi alone isn't enough to hide the device identity from the network. It will only hide one commonly used ID rather than making the device not uniquely identifiable. (ref)
Carriers often detect device model via IMEI and multiple other ways as part of their standard operating procedure. They change how things work based on the detected capabilities but also hard-wired quirks for device models, etc. Devices send a lot of info on capabilities. (ref)
hmop yes there are phone that can change both IMEI IMSI ON EVERY CALL BUT KEEP SAME CELL NUMBER $5000
hmop - IMEI randomization is a poor way to improve privacy and will draw attention to yourself in practice. If you want a fresh identity for the cellular network, there isn't really much alternative to using both a fresh device and SIM.