(Gee, sounds kinda like alpha testing.)
Apparently, the best performing networks are AT&T and Verizon, which fail about 5% of the time when connecting to other services, while the worst, T-Mobile, fails around 15% of the time. Still, 5% failure rate is nothing to brag about, especially given that most telephony devices are based on the "five nines" -- 99.999% reliability.
...so if someone ever asks whether you can be SMS'ed in the event of an emergency, the correct answer is "not reliably, no."
