A solution to limit or eliminate cell phone use in schools

A school's assistant principal in Connecticut found a brilliant solution to the dilemma: Students so need their phones for safety while traveling to and from school, and their phones are expensive and are easily stealable if simply dropped into a teacher's box for while they are in a classroom. But most students are addicted to a level that is unhealthy. This system allows students to keep their own phone in their own backpsck/possession throughout the school day, but it's snap-locked at the beginning of the day upon entering school, then umlocked with a special magnet at the end of the day upon departure.
And parents can be given their child's schedule and the phone numbers to those classrooms in case they have an emergency message to tell their child. Such calls would be minimal. As a teacher, I think this system is brilliant!