Why don't cell phones flash on the first ring, vibrate on the second, and ring normally on the rest? That would prevent the majority of interruptions in classrooms, theatres, etc. Why can't I just pay some reasonable price, perhaps $0.05*, per minute rather than deciding beforehand how many minutes I will use per month and either 1) feeling like minutes are free and I can call anyone or 2) worrying I've gone over and not calling anyone. * More expensive than a long distance calling card, presumably since mobiles require more infrastructure.