Do you have a cell phone detector, someone who can find a cell phone within a certain distance or range, and if so, how can it not be detected?
Of course, there is a high-end basic military status, you can find the phone closed, but also can not determine where the phone, you can only determine the vicinity of mobile phones.
Of course, metal detectors are common, which are common security checks for metal objects.
There is a device to detect mobile phones by signal, as long as the phone boot, you can find the phone, but you can not determine where the phone, you can only determine the vicinity of mobile phones.
