I recently purchased a INMARSAT "ISATPONE PRO" Satellite Phone. Figured it was about time to "bite the bullet" particularly that now I have my father joining me on Safari. Plus he can go shares in it.. The cost was roughly $800 with case and 100min air. The Air time lasts for two years but you can bump it up an additional two years just by adding some more $$ prior to the expiry date. Their coverage seems quite good with exclusions including the Poles and northern Alaska. The Inmarsat also gives a GPS position if required. I also looked at the cheaper Theraya and Theraya Pro but the coverage does not cover the southern part of Africa, Tasmania and the Americas.