I find mobile phones really annoying in classes and especially exams/assessment tests etc.
People deliberatly leave them on knowing that there is a chance that they will ring. They love the show off factor surrounding their phone/ring tone.
In assessment tests and formal exams, a zero tolerance policy should be in place for mobile phones.
Three or four years ago, there was never a problem with mobile phones. Why all of a suddon is there this massive problem? Well, put simply the problem isn't mobile phones, the problem is inconsiderate assholes.