Good if it stops indecencies

Also saw in the papers of bullies who forcefully take phones from other kids outside school. Something for parents to think about when giving their kids a not so cheap phone.
At the same time, would be nice to see the suggested call booths installed so that kids and parents can communicate in certain circumstances. But of course in after school hours the kid may have to initiate the call! (for e.g. if parent is getting late to come and pick up - specially for younger kids). In a big school, parent calling the school and trying to locate the kid (after school hours) is not easy
How this ban is implemeted would be interesting.

Is every student going to be body searched or walk through a scanner at the entrance
Are there devices that can detect a mobile phone that is switched on ?
(for e.g. by picking up the periodic cell to tower singnals)