They are well known (at least in europe) for avalanche transceivers.
Not sure how well the 800Mhz signal will go if you don't have line of sight, 3km sounds optimistic (perhaps between two mountain tops).
The satelite link is fairly easy technically, you can buy modems off the shelf from orbcomm - it's used by a lot of fleet and cargo truck tracking systems.

There are no prices for the satellite data subscription or any guarantees of who is running it or their links to various national agencies.

The ability to locate other people in your party if you are separated is useful - this is a direct handset-handset link and doesn't need the satelite - assuming the pricing means you can afford to have multiple units.