I recently purchased a DeLorme InReach. Useful for both backcountry or more civilized areas. SOS button. Two-way texting with SOS personnel or with your friends and family. Smaller than cell phones were a few years ago, so easy to carry around. No sense having this thing if it is not within reach to use when needed.
The InReach has worked well on test messages sent from several of my favorite remote locations.
You buy the device online or at a local store, set it up online with DeLorme, and choose the subscription plan which you prefer. Read the fine print on the DeLorme site.
I do not have a smartphone, so have not tried DeL's Earthmate app to pair the InReach and a phone.
My advice is to read all of the user manuals (online at DeL site) and watch DeL's instructional videos online before deciding about this device.
So far, I have sent several test messages to/from DeLorme's automated system and to/from some of my friends and family. No problems. I have things set up so random folks cannot initiate messages to me; they can only respond to my messages. I sent my trusted contacts each a message to store; they can respond to that stored message to contact me if there is a true emergency at home. You can go all the way from my bare-bones approach to having the InReach be almost a remote hotspot for texting and sending map info.