At least in my time they were pretty much banned. You could have your phone on you but if you got caught using it during class, they'd just confiscate it. Of course, some exceptions apply like if a teacher informed of some upcoming event, you could pull up your phone and set it in your calendar without getting chewed out. Not sure what's happened since.
At my son's school, they have to put the cell phones into the "phone hotel" at the beginning of the day, and they pick them back up at the end. But it is performance only, really. If the kid really wants a cell phone, they'll just put an old one in the phone hotel and keep their real one hidden in their bag. But even that isn't really done all that much, as they're required to have laptops for class and they can do anything social and/or distracting they'd want to do on the phone on the laptop instead.
I went to primary school in 1999-2008 and it was the same for me. After that I started my secondary education in business school in 2008 and there were basically zero restrictions on smartphone use. Smartphones probably became ubiquitous in primary school after that too, but this law seems to also target secondary schools which sounds stricter than it used to be.
