I think we should go even further: ban all phones during school hours. There is absolutely no reason that kids need to have a phone in school. If the parent needs to reach them, then call the school office who can get your kid on the line. There is no emergency so dire that a few minutes' delay in talking to your child will make a meaningful difference.
> There is absolutely no reason that kids need to have a phone in school.
I commuted one hour from and to middle school and high school, I definitely needed a phone to communicate with my mother when stuff happened (and occasionally happened), such as missing the bus or being late for lunch.
When I was in school, you'd just go the main office and ask the secretary. They had a phone that students could use (for free) when they missed the bus or had to reach their parents for something important.