Using a dumb-phone is the reason a pre-teen neighbor of mine got bullied. So much that she ended up stealing money to get herself a smartphone. Shortly afterwards the parents folded and became less strict with their anti-consumerism stance.
Absolutely smartphones should be banned, at least during lessons, and at best during the whole time in the school, recess, etc.
Giving a child a dumb-phone in an environment where everybody else uses a smartphone doesn't work. If smarphones are not banned then _all_ will end up with a smartphone, and socialisation difficulties, etc...
This is a case where individual freedoms end up in collective damage. Maybe I'm an outlier here but I'd ban all kinds of social media all the time.
