It is fine in most schools for children to have their phones in their bags as long as they are not using them in lessons, which I completely agree with. Children have plenty of time to have a chat with their parents when they are not at school. However to really excel at school they must focus on the subject. Think of the poor teachers trying to teach a class of kids who are addicted to their phones or on facebook trying to teach a lesson. How would that work?
Phones are merely a distraction during school time and in no way aid education. Computers can do everything that a phone could do, but have filters to stop you to go off task. I can not see any plusses of children being allowed phones in school.