When I was in school it was beepers. They'd confiscate one from me every 2 days. I'd just go buy another one and get my acct. switched over to it. End of one year the principal called me into the office and gave me back 27 beepers and 2 of those old school grey cells with the antenna you pull out.
They kept our stuff til our parents came and got it, but my mama wasn't gonna go up there to get my beeper or cell. In all honesty, I think they did it to prevent us from being able to conduct criminal acts during school operating times. It's not like when I got a beep I wouldn't skip the next period to run across the street.
I do know this, if I buy my kid a cell for emergencies, and a teacher feels the right to take what I bought for any ammount of time exceeding that day of school, we gonna have some problems. What if my kid is attacked, or in an accident on the way home during that time period and left without a means of communication?