This is not legal in the United States. Intentional jamming of mobile phone signals is against FCC regulations and federal law. Schools have tried jammers in th

This is not legal in the United States. Intentional jamming of mobile phone signals is against FCC regulations and federal law. Schools have tried jammers in the past, but they have been forced to take them down. Prisons have wanted to utilize them, and have tried to get exceptions to FCC regulations, to no avail. As for handing over mobile phones: that is a prudent step. One of my professors took them up before the exam without advance warning for the final exam, where restroom breaks were definitely going to be utilized due to the length of the exam. Obviously it does not solve the problem. But, according to far more than a few studies, having the phone out of sight raises exam scores. Having the phone in a completely different room raises the exam scores even higher. Basically, your brain treats the phone as an extension to your brain, and in its presence, your brain effectively goes on holiday.