in my opinion yes why not because
In case of emergency (a fire, an attack, a traffic accident on the way to school or from it) the more working phones people have, the better it is.
A smartphone can be a study aid. Smart books which provide you with more information if you scan a QR code have become a normal thing in the educational process in many places.
A smartphone with a big enough screen can even substitute a bunch of of school books. I would rather see my child walking around school with a tablet or a smartphone than with three or five kilograms of books.
Teachers are less likely to bully their students if they know that they could be recorded and end up on YouTube.
Though phones could be used to harass, they can also be used to prevent harassment.
Smartphones and cell phones are no longer toys. They are tools of interacting with the world, including working and studying. Instead of banning them, schools should teach how to use them properly. Silent mode and airplane mode are there for a reason.
Of course, there points at which phones should not be allowed. Football team members should not carry their phones during the games. Cheating should not happen. But this does not mean you must ban them everywhere else.