What some of my teachers did was put their lecture notes online and send emails about any updates, assignment information, etc., so going to lecture was completely optional, all the information was available on the class webpage. One teacher had the in-class assignments count for ten percent of your grade, but if you didn't show up regularly, would simply weight your final for the difference.
With or without that, a good chunk of students still came to class. They were the ones who wanted to learn directly from the professor, ask questions, etc., so technology wasn't really an issue with them- if they wanted to fuck around they just wouldn't come to class. The kids that didn't want to be there just didn't show up, but if they wanted the grade they'd have to study and learn the material on their own time, which I think is fair.
The teacher's that try to be strictest about this generally have the most problems when it does come up. Students instantly assume the teacher is uptight, and when, sometimes, a phone accidentally goes off they'll get quiet and look around, making the class a lot more awkward and tense than it has to be.
If you don't want to put your entire class online, but don't want your students just fucking around in class either, say there's a no technology policy, but don't stop the entire class to chew out every student you catch. The more the students like you, the more likely they are to want to listen and respect your rules. Obviously no noise- no talking, no ringers, etc., but let it slide otherwise. Poke fun at a student and embarrass them if it does become a problem, but then move on like nothing happened. This keeps the class at ease, while at the same time, they'll want to avoid the humiliation.
If a student does it more than twice, or twice in a session, then I think it's fair to tell them that if they want to fuck around they can leave the class, but move on afterwards, staring a student down just makes it a lot more tense for everyone else.
You could, alternatively, dock points every time you catch a student fucking around (only do this is if they're distracting another student- a kid who's clearly being quiet and disturbing nobody doesn't need to take the hit, it's their own problem and they're ultimately fucking themselves without your interference). This is a much stricter approach and it might not go well with the students, but if you can keep the class interesting otherwise, they might respect that stance.
You have no obligation to answer the questions of a student who missed information because they weren't paying attention.