The dreaded time is here!

[terracore]

This is not a recommendation for a specific product, however here is a link to get your started: http://www.inreachdelorme.com/. Only about 10% of the planet is covered by cell service, the rest of the world can only use satellite (or wired) phone communication. The kicker is that even satellite phones or panic buttons have a lot of places they don't work, so the best devices can use both or either services. Most of the higher end SOS devices have a method of sending out ping signals so if somebody doesn't check in and can't be reachable, their last known location is available. Unfortunately, even with today's technology there is no sure thing. Malaysia Airlines flight MH370 was sending out signals, was being tracked by radar, and was a big enough chunk of metal and technology to be seen by satellites, but we still haven't found it a year and a half later.

Sorry to hear about your father-in-law and best hopes for a speedy recovery.