When I taught, it was in private language schools, so I was pretty much on my own as to determining the rules necessary for running the class. Also, since I had so many different groups of students in different settings, I therefore had to have many different sets of rules.
In classes with children and teenagers, the only electronic devices I allowed were electronic dictionaries/translators, the use of which was more restricted as the language level increased. (I also allowed e-books, but, these weren't disruptive, so long as the student had the right book displayed!) Cell phones were strictly verbotten. If a student couldn't be trusted to not use the phone, it went in a box on my desk and he got it back at the end of class. It would have been utterly unthinkable (and illegal under Russian law) for me to hold it beyond the end of class or demand some kind of payment (in money or otherwise) for its return. If the student didn't want to stop using his phone and refused to surrender it, I showed him the door. (That happened only once.) I spoke with his parents, explained my rules, and asked them to help with a solution. (That happened only twice, and the parents were very apologetic.)
I trusted adults a lot more, and also agreed that adults should have the right to suffer their own consequences for not paying attention. I never once had an adult actually talk on the phone right in the classroom or make excessive noise with a phone. If they didn't want to pay attention to me, however, that was their own problem. Granted, it was annoying when an adult in an individual lesson used a cell phone, but I justified it this way - the adult is paying (and at a premium) for this one-on-one lesson of his own free will, and he is talking on the phone during this lesson of his own free will. Therefore, he realizes that he is paying a lot of money to talk on the phone while I just sit there doing nothing while still earning money.
(The same happened with tardiness, whether adults or children - the meter started running at the scheduled start of class, not when the first student wandered through the door. There was one morning adult class that started at 7:40, and my students were notorious for not showing up for up to half an hour later. I explained to my bosses at the language school that I was getting paid for so long for just sitting around and reading the newspaper. Their philosophy was the same as mine - if the students choose to be late, then it's their choice to pay me for sitting around and reading the newspaper!)
I also had groups of workers at their workplace, and since I was essentially the guest, and since I had no control over what happened in the workplace, I had to tolerate cell phones, tablets, PDAs, and whatever other electronic devices got used. They were always polite about it, though.
