It's ages since I last looked into the costs involved in getting a sat phone (GSM completely overtook the idea) but, a few points to note:

- It will enable them to make a call from the deck of their cruise ship but will it really be less expensive than the on board ship to shore calling facilities already available?

- On shore, even the most exorbitant outgoing roaming charges will likely be less than the cost of using a SAT phone.

Satellite phones are not really for your typical leisure travellers. If your idea of fun is camping in the dessert or winter photography expeditions north of the arctic circle (or even if you regularly drive off the beaten path in the US or Australia) then a sat phone is pretty much mandatory IMHO.