Through high school, I'd say smart phones have no place in the classroom, so I fully support banning them. Use laptops or tablets, especially if they can be restricted to academic content only. Make them keep their phones in their lockers, can be used in between class or the cafeteria at lunch. Parents will have to resort to the old-school means of calling the school if they need to reach their kids urgently. Make sure classrooms have some kind of regular hardwired phone and/or radio for emergencies, which all mine always had phones.
Now we just got to figure out a way to restrict kids from using AI for all their homework. We are quickly building the next generation of tech dependent kids that just Google or ask AI for everything and don't actually learn anything.