Both pupils and staff at East Otago High School will now have to put their devices in a box at the front of the classroom at the start of each class, and retrieve them at the end of each class.
Some schools still allow them to be used to do work in the classroom, but pupils have to have permission from the teacher.
East Otago High School is among a growing number of Otago secondary schools which no longer allow them to be used for anything in the classroom.
Deputy principal Keith Fleury said the school made the change, with immediate effect, following an extensive review of school practices by an independent education consultant.
An extensive survey was conducted and parents, members of the community, staff and pupils were invited to participate in personal interviews with the consultant.
''One of the common barriers identified was mobile phones in the classroom - a very loud call to ban them.
''As we are not going through this process for nothing, we are acting on the feedback. Hence, we are banning all mobile phones from all classroom situations.
''We are including staff in that, as well. It is important staff are role-modelling the ban.''
Mr Fleury said the ban had not extended to the entire school premises ''as yet''.
He said the school had continued to allow pupils to use them until now, because it believed they were a ''powerful tool'' in a variety of teaching and learning situations.
''We were persevering to try to ensure that those situations were available to students, but as other schools have also found out, it just got out of hand and the negatives outweighed the positives in the end.
''They were not being used for the reason that they should have been used for, and it just takes their concentration away.
''It's almost impossible for staff to police these days.''
The school now provided tablets and computers so pupils could continue to access useful apps during class time.
He said cellphones in schools was becoming a ''hot topic'' around the country and internationally.
''We tried to get a guy called John Parson in to talk to our students on cyberbullying, but he is booked up until July 2019.
''It just goes to show how schools are struggling and how they need more professional targeted help in dealing with the technology out there.''
Mr Fleury said one of the reasons schools were banning cellphones was employers were telling them they were looking for relationship skills in employees.
''Mobile phones are having a big impact on developing those skills. Just look around, anywhere you go, heads are down and everyone is ignoring each other.
''The current generation we are dealing with have been dubbed screenagers, for very good reasons.''
He said most of the school's pupils were born between 2000 and 2007. The first iPhone came out in 2007 and up to the end of last year, more than 1billion had been sold.
''That is only Apple. Our students have known nothing else ...
they have a desperate need to tell everyone what is happening all the time and just cannot live with the thought they might miss something.''
