Unless you jailbreak your phone you are basically forced to trust the vendor. Even with a jailbreak there are lots of places to hide something like this. If there is a hack in the baseband firmware on your phone you are basically out of luck.
> If there is a hack in the baseband firmware on your phone you are basically out of luck.
You are out of luck. Around 2005/2006 it was revealed in a mob trial that the FBI remotely activated, presumably using a special signaling plane command, a non-smartphone to turn it into a room bug. Ain't no firewall for that.
