Things like this happen at school unfortunately.
I hope they catch the person who did it because it's only the beginning of a crime spree for them at this age!
Poor girl though...it's a huge wake up call when you're that age to have something like this happen. I remember having my car broken into when I was 16 and I was devestated. How could someone do that? Life revolves around "you" at that age so it's very disconcerting to have that life disturbed. She'll recover but she'll always remember this.
Did she leave it unattended somewhere? She'll never do that again.
My brother did that and had his backpack stolen in High school.
I hope the cell company can do something. Did you report it to the police? I know they probably can't do much but at least if there is a case file number and the cell phone does come up with something they could scare the perp a little.