Is it possible to build an app which allows for full duplex audio conferencing? Is there one out there I haven't found yet?
I work in a theatre and our comm system is failing. Everyone has smartphones so it would be easy to utilize these as comm systems. We use a full-duplex system with a talk button.
You don't even need an app. WebRTC will suffice.
There are some off-the-shelf libraries that wrap everything up for you very nicely:
Since you'll be using headsets, I recommend disabling echo cancellation as you won't need it and it only hurts sound quality.