Yeah, the baseband processor runs its own independent RTOS with full software control. Without studying, in detail, the electrical connections between the baseb

Yeah, the baseband processor runs its own independent RTOS with full software control. Without studying, in detail, the electrical connections between the baseband and the rest of the hardware it's not possible to say that it can't record from the microphone independently of the hardware. It's easier to make that argument for the SIM card, which is actually not a SIM card but also a small ARM core that runs Java code. You can embed small programs into the SIM card which is something a lot of carriers do. The SIM card and baseband work in tight concert though and you should just assume that the connections of the baseband are available to the SIM card.