I sent the last student to the principal's office for refusing to get off his cell phone texting.Gave me the middle finger.
A friend of mine who is a teacher solved that issue permanently. He went and bought a cell signal blocker. Turns it on before class turns it off after class. Problem solved. Nobody can use their cell phones when the signal blocker is on. His biggest advice was to not tell anyone that you have one, that way no one can complain about it specifically. Just play dumb if they ask why there is no cell signal in your classroom.
A couple of the other teachers caught wind of what was going on and six months later half the teachers in the school have cell signal blockers in their classrooms.