At some point, I'll try to write up a summary of all the gizmos out there. The basic message is that there's no one magic solution for all situations.
There's a lot to be said for Satellite phones. They can both text and use voice. One of the Inmarsat phones can track; text, voice and has an emergency activation button. It runs off a geosynchronous satellite so, if you get a signal, you won't lose it. If you don't have a signal (about a 30 degree horizon), you're totally out of luck. Good for probably 90% of where you're going to be.
Irridium phones are good, but don't expect more that 3 to 8 minutes of voice in most Sierra terrain. Texting is fairly good, but may take 20 minutes to get a lock to send. Not sure they have emergency activation and tracking yet. But haven't really checked. Still, they're really dependable and useful.
Globlestar satellite phones don't seem to be that dependable (fewer satellites), though I have limited experience with them.
SPOT. Not tried these. Experience is they get out a good emergency location and track with a fairly high percentage of accurate signals. When paired with phone, you can get out a text message -- a definite advantage, though two way is better -- currently not available with SPOT.
DeLorme. As a standalone it's got an emergency signal, 3 pre-programmed text messages and tracking. It can pair with modern smart phones (Android or iPhone, iPad, iPod) or the DeLorme GPS to get two way texting. Seems really nice and I ran into a number of hikers using them. Warning is that the GPS sucks down batteries (AA) when in paired mode or tracking mode. Pretty annoying. Not sure about battery life when paired with a phone. The standalone unit seems to have good battery life. You can choose to have the emergency call-out to go either to SPOT command (monthly fee) or a user-created list of up to 5 email or cell phones.
SHOUT! Nano or GeoPro. These are really good, but designed and marketed for agency use.
Although there's a lot of bad press about people hitting the emergency button for trivial reasons, most of the calls in my experience are legitimate. It's a huge advantage to know the exact coordinates and the problem (outbound text messaging). It's even better if the agency can ask questions (inbound texting or voice).
All stuff to consider.
George
