There are so many things wrong with this mobile phone pouches business.
Why these expensive pouches? Why can't children just switch their phones off completely when they arrive in school and leave them off till the school day is over?
But why would a child need a phone at school anyway? A child having an emergency while actually in school doesn't need to use a phone, the school will do the necessary contacting of emergency services, parents, guardians etc.
Far from being necessary for school work during classes, many schools have a complete ban on phones during the school day.
Not only are children getting phones, they are getting very expensive smartphones, although a cheap 'Nokia' would fulfil any emergency contact situations they might have. If one of these expensive smartphones were to go missing while handed in at school, there'd be hell to pay, so there's probably a perceived need to keep them super-secure.
There is a solution which doesn't place on schools the burden of storing expensive smartphones, and frees up that E9m for better purposes:
don't give smartphones to under 16s. The actual average age is NINE years old.