(Via the Drudge Report)
On the ready.gov website, you're urged to "Get a kit; make a plan; be informed". Apparently the use of your cell phone in an emergency violates these concepts.
Snarkiness aside, you can't rely on your cell phone in a big emergency. The system simply isn't built for the volume of calls. Bear in mind that you might be able to get a text message through where you can't make a call.
And make some alternative communications plans, will ya?