Can a smartphone be of any use if the internet/cell service goes down?<p>Most messaging apps depend on having an active internet connection. All modern phones have WiFi mesh and Bluetooth/BLE hardware capabilities, but it seems there are very few apps that use them.<p>The existing apps have little overlap across platforms. Bridgeify is the only one that exists on both iOS and Android (although I didn't manage to make it work between different platforms).<p>I'm looking for an app that could help people communicate using their iOS/Android phones without internet connection by relaying messages peer-to-peer.<p>If it doesn't exist, any ideas why? How would you build one?