This is something this is addressed in hospitals too, the answer is a no audible cell phone zone. You post a sign that this is a no wireless zone and all are warned, so classes, certain areas in hospitals, by just being in the zone deadens the phone, but as soon as you leave the selected area, you have service once more and texting would continue to work though, in silence. BD
This can have all kinds of potential, like even movie theatres as there’s even more you can do, like disable taking pictures and videos too and an emergency type of text message could still get through, just no noise. BD
This is either the best or worst idea ever, depending on your point of view. Microsoft has patented what it calls a "device manners policy" (DMP), a wireless zone-enforced device protocol that allows local operators to turn certain features off (or on) based on local manner and safety policy.
Similar to how wireless service on planes can lock out voice but allow data, Microsoft's DMP concept would allow local czars to enforce, for example, "no talking out loud" or "no photography" rules. Audio recording could be disabled at concerts, video recording killed at theaters, and ringers turned off at funerals. Of course, this all requires manufacturers to comply with the DMP protocol in their devices. In the end, we'd be looking at a pre-movie PSA that says "your phone is now being put on silent" rather than "please turn off your cell phone.