GoTenna pairs wirelessly with your smartphone, enabling you to text and share your location with anyone who has the device even if you don’t have service. No towers, routers or satellites required!
It is an interesting concept one that I will adopt early to see if it works because I love to travel.
Think of it this way. If you go to the mountains and there is no cell service then you can use the goTenna that is paired to your active cell phone (given you have power) and the message will come through your device as a text style message.
Perhaps it will evolve it pics, voice and other formats?[SOURCE](http://gotenna.com/)