We had Satellink and were very unhappy with it. If a page was sent at the exact moment that you lost the signal, you were out of luck -- unless your company was aware of the problem and sent mulitple pages. Even then, you weren't guaranteed to receive all pages.
You can probably find cheaper services, but i would highly suggest taking LittleBigTruck's recommendation on this one.
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Godspeed to all of you out there on the highways and byways!