When the cellular system was heavily damaged and strained during Katrina, text messaging was the only to communicate even as far away as here in Baton Rouge (80 miles from New Orleans). Some folks were actually rescued from the flooding by using text messages to family out of state, who then contacted disaster response here in Louisiana. My advice is keep your messages short, use a lot of abbreviations (ask your kids if you don't know them already), and only send messages when you have to.

.....cliff
(like, who else?)