Turn your smartphone into push-to-talk walkie-talkie & txt messaging when out of range cellular data network.
https://www.wired.com/2016/02/beartooth/
https://www.beartooth.com/?gclid=CPrOh4evktICFU08GwodNEIA8w
https://www.wired.com/2016/02/beartooth/
https://www.beartooth.com/?gclid=CPrOh4evktICFU08GwodNEIA8w