I think every classroom should have a soundproof box in which students put their phones on the way in. Let them have them back between classes. If they are caught with a phone during class, automatic suspension.
Good idea.
I think they should not be allowed at all during school hours. You put them in on the way in — staff as well as students - and pick them up on the way out.
In between breaks, students should learn to interact with each other in the analog world