I like the SMS idea too, assuming the towers aren't knocked down. Cellular carriers should be encoraged or required to have an emergency plan that includes shutting down or severely curtailing the ability to make voice calls except for special phones issued to emergency responders. That would reserve the available bandwidth for SMS text, which everyone else could use, and which would have a greatly increased chance of getting through. The phones themselves would display a message on their LCD in such a situation, saying voice service was out but SMS was avaliable.