Simply pressing the SWITCH OFF button is not enough. The software is already running in the background to detect when you will again press the button to switch it on. Most mobile phone (old ones) had removable batteries. So you can expect that you can switch them off. But newer phones with android and iphones do not come with removable batteries, so switching off such a phone to a completely zero activity state is not possible easily.
While, it can also be debated whether a phone requires a battery at all. Air circuits can capture free electricity from radio waves. Nikola Tesla has demonstrated this a 100 years ago. People today are using RF signals which is nothing but low power wireless electricity being detected by another receiver. Wifi, 2g, 3g, 4g, whatever you call it, its simply electricity through air. More the voltage, more the power.
We already know about GPS. This can be used to detect presence of a person with a mobile phone anywhere in the world. its not hard to find out.
It is possible to incorporate special software and hardware in these mobile phones, that will make it look dormant when switched off. However, they can be activated remotely, and can be used to broadcast audio frequencies that could not be heard, but causeheadaches and migraines, even when the phone is off. In other words, Control over humanity can be achieved through technology.
YOU ARE BEING WATCHED!!! - could be a reality.
Science and technology has advanced many folds during the last decade. But it is still to be found, whether this is for good or bad.
To all evil scientists:
Please do not consider this a suggestion.
Tesla wireless electricityhttp://www.damninteresting.com/teslas-tower-of-power/