Cell phones suck in many places for emergency use. I cannot speak for other areas; however, living out here in the western states and hiking all the time, I don't even carry a cell phone. I leave it in the truck or the trailer. For GPS I use a Garmin; and for help if ever needed, I carry an ACR ResQlink personal locator beacon. Can be used anywhere. When you need emergency help just pop the antenna up and press and hold the button. It will send out a 406MHz to the SARSAT system.
The Search and Rescue Satellite System, or SARSAT is a set of satellites circling the earth. the signal is great for getting through dense tree canopy and other obstructions; a lot better than a satellite phone signal/ This signal sends an identifier code of the PLB and also sends your GPS location to a US facility. They then notify the local authorities per the GPS location and from there emergency crews will be dispatched to your location.
It will also send out a different frequency monitored by local SAR to also help pinpoint and will flash a very bright white LED to help in night time rescues.
These are FOR actual emergency use.
The purchase price is all it costs, usually just under $300.00. Battery is good for about five years, replacement batteries can be installed for about $100 and at the time they install the replacement they also install new seals and check water/dust intrusion.
There is NO monthly fee, they do not work off a satellite phone system or require a monthly fee like other units.
Living in Moab UT and knowing quite a few on the grand county search and rescue, these are more helpful than you can imagine. If you hike alone I suggest it. I do the same with my dogs in national forests and BLM lands in MT, ID, WY, UT all the time and I am never without it.
I HAD a very good friend who died in Glacier National Park hiking in July 2020. We had discussed the use of a PLB and he always said it sounded like a great idea and he was going to get one; since like me, he hiked alone all the time in wilderness areas. Well, he didn't, and he died hiking in the park. All I can say is at least he died doing what he really enjoyed and in a place he loved more than anything. But I wonder, was his death unnecessary? We will never know.