If you can afford it, it's probably the best communicator you can get. It has 2-way texting, satellite gps tracking so others can see where you are, and couples with a map app, to show you where you are on a map.
I picked up that info from the REI website
where it sells for $300.
I have a SPOT 2, which sends out tracking locations where others can see where I am, but it doesn't give me confirmation that my signals are being received. But the idea that family and friends know where I am is a high value deal for me. The DeLorme unit offers that plus much more.