Is there a way to talk on Android Zello when it's running in the background?
Zello will work with wired headset while in the background with the screen off. Just make sure to adjust these settings:
1. In Zello Options > Push-to-talk button> tap drop down menu and then press the wired headset button.
2. In Zello Options > Push-to-talk button action to Toggle
3. In Zello Options > Push-to-talk button check Handle headset buttons when in the background
Then you should be able to use the button on the wired headset in a toggle mode -- press once to start talking and agan to stop. Hold to talk mode will typically not work because of design of wired headsets-- they short the mic when button is depressed.
The same may work with Bluetooth headset however the compatibility vary between different Android devices and headsets.