Most schools where I live in have a very strict policy of no phones for students in 10th grade and below. There are regular bag checks and everything, if you're caught- it's straight to the principal. You can only bring them when you've asked for permission, usually for emergency purposes. That too just on rare occasions.
If anything happens, parents themselves can call the school and vice versa. This stuff gets super lax with 11th and 12th graders lol, obviously you can't be seen using it without permission by the teachers but they usually don't care anymore. Still, there are exceptions. My previous school was very strict even with 11th and 12th traders. I personally really like this system. I feel like this gives children the opportunity to actually behave their age and live life yk.
Our school doesnt allow phones unless you live outside of town (doesnt matter if you at the edge of town or at a remote rural place of town, so long as you're from town they dont permit lols) or have a medical condition. We register our phones/get permits at the start of the school year. Also they do random bag checks all throughout the year and confiscate those with no permits, and a parent is required to claim it after school. (This is in highschool, if this policy happened to you in uni dang switch schools idk)

In my school they're going to take our phones and give it back after our class is finished inside of big shelves (most of the schools have the same thing right now currently) and I'm curious if other countries have an similar method with teachers taking phones away