Satellite Phone: Buy or Rent?

A friend of mine is looking into a satellite phone system to stay in touch during an upcoming trip. He's thinking about the Qualcomm Globalstar GSP-1600 unit, but hasn't made up his mind whether he should rent or buy. This satellite phone will provide Internet and email access with the optional data kit--it's not fast (9600 k), but at least it's something. Rental looks like it might be the best choice, seeing as he won't need to use the satellite phone for an extended period of time. But he's also looking into the option of purchasing a used unit. It seems that the per minute charges are the big catch with satellite phone rental ... it's cheap until you actually have to use the thing. The weekly rental fees are deceivingly low. But spend an extended amount of time on the phone and you'll shell out a good bit more by going the rental route, considering the excessively high per-minute charges.