Not a bad idea if your way out on your own...
Link to more info..
http://www.sarsat.noaa.gov/emerbcns.html
Don't know who eventually pays for the rescue costs..
You'd probably need extra insurance for that.
In article , matt weber
writes:
Then there are brief case phones that use the Inmarsat spot beams.
They weigh a few pounds, and will also work almost anywhere in the
world.
Within the USA, I beliver Amerisat sell phones that provide coverage
only in the lower 48.
However if you are really concerned, for about $850 you can buy an GPS
enabled EPIRB. You set that thing off, and in about 5 minutes alarm
bells start going off, and within 20 minutes, your position is known
+/1 about 35 feet, and the fact that you need help is also known. You
can expect a Search and REscue Helicopter to come after you within an
hour. (At this time 406Mhz EPRIB's are legal for land use in the
USA). The McMurdo FastFind Plus weighs about a much as a cell phone
can be carried on a lanyard around your neck.