If I was talking to my mother on my own time, and not disturbing anyone, and a teacher pulled the phone out of my hand, that would be the last time she used that hand.
If I have to worry that everytime I talk to my mother may be the last time I ever talk to her, no teacher is going to stop me, and if they did, I wouldn't be foul mouthed or throwing pies, I'd be using a baseball bat and bashing their skull in.
The kid should have beaten his teacher senseless for her conduct.