Unfortunately, we can't even entirely trust our phones then either. You can turn on airplane mode in the OS, but it could still choose to reactivate the radio f

Unfortunately, we can't even entirely trust our phones then either. You can turn on airplane mode in the OS, but it could still choose to reactivate the radio for short bursts without you knowing. Or the the radio could be set to phone home on a regular basis on its own recognizance. This could potentially occur even if the phone is turned off. There is no way to ever completely trust a cellular device.