[Boeing Guy]

Sorry to say Retlaw, it does not work like that. I have access, through my job, to a handheld satellite phone, its a recent one and not really pocket sized also the costs of call's are a lot more than cell phones.
Also you need line of site for sat phones, that's why deep Africa is great for them, the satellites are positioned over the equator.
Cell phones use different bandwidth and the strength is much weaker.

If the cell phone companies had worked together better then there would be less masts as they could have shared stations. Not forgetting the last governments involvement in selling the 3G band at a very high cost.