This is an awesome project. After watching all of his videos this[1] one is the most curious, because you could probably get his phone number by measure the time it takes for a digit to dial.
Not that this is something I would endorse but it came to my mind the second he tried to hide the dialing process.
[1] https://www.youtube.com/watch?v=v_e1oqCkeng&feature=youtu.be...