I try to get them to realize that they are being disrespectful to themselves more than anyone else and that those who continually draw their attention from learning are also disrespecting them. The student has made a decision to make themselves better through education and when someone texts them about essentially nothing it is saying in broad terms that they don't care about the decision the student has made and feel that the mindless chatter they have is worth more than the students education. By setting this precedent of being on your phone is the perpetual undermining of your own decisions/education and is a simple matter of self respect, many of the students simply don't use it as often in my classes and if they do I remind them how important their choices are and how this education will almost always be worth more than that text or in some cases that relationship.
If this doesn't work I quickly move to downgrades to show them that I am serious about the situation and that they will not sit in my class and willfully break the rules without consequence. Consistency is the key to making it easy. If everyone knows phone = downgrade then it discourages most students from bringing it out. When phone = "I'm not really sure" there is less inherent deterent to bring it out in the first place.
