AFAIK know phones are banned in all secondary school (and primary school) from the start till the end of the school day. My daughter just started secondary school and one kid was trying to text her mum to add credit to her lunch money account in the first week and got a one hour detention for getting her phone out during school. This was in the canteen, not in a lesson. Bit harsh but seemed to get the message across.

Ironically most homework is done by the kids on their phones so when I tell her to get off her phone she always has the excuse that she's checking/doing her homework, or looking at her timetable online.

[edit] note this is a UK perspective, not sure why this got downvoted