Text messages require less bandwidth, which means they are able to transmit more reliably during emergency situations. Plug in your mobile devices ahead of a storm and put you phone on low power mode or airplane mode to conserve energy.
Power Resources in the Event of an Outage
Consider purchasing a portable chargers or "power banks." These devices can store enough battery power to charge your phone multiple times over.
Consider using your car battery to plug-in your mobile device(s) during a power outage.