So you want to stay connected with your friends even when your phone does not have any service? Beartooth can help. It is an off-grid communication device that lets you talk, text, and view maps in the outdoors. You will be able to talk with others with a tap and track others in your group. It has a LOS range of 5 miles for voice and 10 miles for text.
Beartooth comes with a 3000 mAh battery to charge your phone. It offers 256-bit encryption for your privacy. With mesh networking you get an extended range. Beartooth is available for $99 for a limited time.