We have a small amount of low-cost networking gear at camp (raspberry pi, WRT/tomato routers, 2.4 ghz directional antennas, etc.). One common time sink is walking back and forth between camps to ask a simple question, then walk all the way back with an answer.
What are the best (simple, utilize existing infrastructure) methods for text and voice comms without using internet. Cross-platform would be ideal, but Android would be the primary OS.
The FOSS project Rumble is interesting because it uses Bluetooth, WiFi, or internet to get messages through. Unfortunately, it doesn't look like there's much ongoing development.
There's a free "Wi-Fi Talkie" app in the Play store that we've tested, and that too seems to have little development (last activity April of 2016).
So, those sorta work, but what are we missing?