Safe America created the Text First. Talk Second. to raise public awareness around the importance of utilizing text messaging for non-emergency communications during a disaster.
When disasters strike, voice networks can become congested with people trying to call each other for non-vital communications. This can result in people in desperate need of help being unable to contact those they need to reach, such as emergency services, friends or loved ones. In some instances, this may also result in emergency service personnel being unable to communicate with each other.
Here is what you can do: http://www.safeamericaprepared.org/component/content/article/89.html