Firmware, on the other hand, is software that is embedded in a hardware device, acting as a bridge between the hardware and higher-level software. For mobile phones, firmware controls everything from the user interface to the communication protocols that let your device connect to the cellular network.
No secret firmware needed on your phone – the attacker uses a fake tower to downgrade you to GSM (if VoLTE disabled) and forces encryption off (A5/0). That’s not firmware; it’s protocol weakness.
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that explains how the secrecy of the A3, A5, and A8 algorithms—which are embedded in firmware—historically failed to prevent security breaches. Exploiting Baseband Modems
You cannot simply "delete" the secret firmware. It is often in Mask ROM—literally etched into the silicon during manufacturing. Throwing your phone in a microwave won't fix it; it will just break it.
