When I was a kid an young adult, there were no cell phones. People had emergencies. They did like everyone else: borrowed a phone or used a pay phone.
I find it rude and socially unacceptable to speak on your cell phone in a restaurant and am annoyed to no end by cell phones in classrooms. There should be an automatic dismissal from class that day for college courses when your cell phone rings -and in many of the classes I've attended, that's the case. In one, the professor requires that you meet with him before coming to the next class if it rings. His rule is that if your phone rings, he assumes that there is an emergency and you are to leave and not re-enter class until meeting during office hours. A fair policy.
I know that high schools also have problem with cell phones, and this is a place where jammers should be employed if they haven't any rules prohibiting cellphones.
Cell phones used by motorists are also problematic, and using them while driving should be a ticketable offense. If I need to use the phone, I park. If my phone rings while I'm driving, I let it go to voicemail. This is simple. Actually, I have a cellphone that almost never leaves silent mode. Some have vibrators that are just as noisy as ringers.
If there was one piece of technology I could "un-invent" it would be the cell phone.