Using a Wireless Network for Personal Emergencies?

An anonymous reader asks: "A friend asked me this today and as I began to think about an answer I realized it made for a perfect Ask Slashdot question. His question was: 'Now that our illustrious Attorney General has gone as far as to suggest that families put in place an emergency communications system between themselves, I'm shopping for the right solution. I think RIM because it allows me to enter text and to rely on the pager network rather than the cell network. But the last that I looked, it was still impossible to do without my own server. Enlightened Ones: what suggestions might you have that would allow us to each have something in our pockets and is most likely to be fault tolerant to a messy event?' Having had the experience of using my Crackberry in NYC on 9/11 as the only stable means of contact, I too wonder whether this is the next big thing? So I turn the question over to you at Slashdot -- If you were in need of a hand-held, wireless data device and wanted to use a data network which was likely to survive, what would you use? Which arcane pager or emergency information networks were designed for survival? What if you wanted it to easily work with POP email? How about for reasonable data rates?" Assuming we are not quote to the point of a truly fault-tolerant network, what would need to happen for it to become reality? Which provider is close to putting something like this together?