In the OP's situation, I would be looking at sat phones. They're expensive kit, but they're so useful that they may hold their value as an investment. Sat phones work anywhere. This is the technology aid workers carry when they're visiting war zones and earthquake zones, since they require no local infrastructure. The big brand when I worked in the international aid field some 15 years ago was Thuraya. I believe other satellite systems are available.
A lot of personal locator beacons (Garmin inReach, SPOT, etc.) offer satellite text messaging as well as contacting emergency services when needed. Texting isn't nearly as convenient as talking but I'm going to guess that the locator device and a subscription cost less than a satellite phone and monthly service. They work almost anywhere, which I suspect is the case with satellite phones. Terrain and tree cover can have an effect on any transmitter in the frequency range used by small personal communication devices. The nice thing about the locator beacons is that they're small enough that you can stick one in your pocket any time you're working or playing in an area without phone coverage and want to be reachable or able to call for help.
They can be very small. The Breitling Emergency has a satellite distress beacon built into a watch.
Other colours are available. They have been used in real emergency situations about twenty times apparently.
Its like a thicker version of their classic Aerospace ana/digi with a pull out antenna.