I'm looking for a satellite phone service. What's the difference
between Iridium, GlobalStar, etc.?

The Iridium phone will work from anywhere on earth for one price per
minute no matter where you're calling from or calling to.  Iridium is
the best option if you travel to remote regions througout the world or
at sea.

Globalstar covers large parts of the earth and is the best option if
you're looking to us a Satellite Phone primarily within the US &
Caribbean and ~500 miles off each coast.  It is the better option in
this "home" area because it has a much lower per minute rate, has
better voice quality and has a US based phone number.  The Globalstar
Satellite Phone is also about 1/2 the price of the Iridium.  You can
do a search for Globalstar Maps and see the areas it does cover around
the world.