InReach devices allow you to use the Iridium Satellite network, which provides coverage worldwide from pole to pole provided you have a clear view of the sky.
I've been using InReach devices for several years now. An InReach device allows you to send and receive text messages and notify emergency responders with your location. They also allow your family and friends to track your location using GPS. They are rugged IP67 rated devices and can be paired with a smartphone or used independently.
Messages can be sent to cell phone numbers and email addresses. You can also post to Twitter and Facebook. You can elect to have your location included with the messages and posts.
Depending on the model, they are somewhat pricey ($300-400 range) but they are worth it if you spend any amount of time in remote back-country areas. They also require a monthly plan, which range from around $12/month to $80/month depending on your needs. I have the $12 plan and usually wind up paying a little extra each month if I go over.
InReach's primary competitor is the Spot X, which I haven't used. I did briefly have a Spot 2 device, which allowed for one way communication, tracking and emergency notification. It seemed to work ok but didn't meet my need for two way communication. The Spot X has added two way messaging.
Three generations of InReach devices. The 1.5 version on the left lacks a screen. It can
be used independently but requires a smartphone for two way messaging. The 1.5 version began
having issues lately with its GPS which resulted in the upgrade to the Explorer+ model.
Screenshot of the InReach Explorer+.