FireChat it works without a data plan and where there is no Internet connection or cellular phone coverage. It even works on a plane or on a cruise ship or inside your RV. It creates its own communication network that’s free and doesn’t rely on traditional networks. and the app is a free download.
You don't have to do anything special: just use your phone and FireChat. This is game-changing since you can create local communication networks at zero cost and also stay connected during sports games, rallies, in RV parks or while boon docking with zero cell coverage at music events and in disaster situations.
I first heard about this a few weeks ago when I reading a story on burning man that this was the way to stay connected. I downloaded it and installed it then I was camping in a remote area so I tried it out and it worked as stated.
Fire Chat - Rods RV Needs