We've simplified the configuration steps for adding accessory and mapping device buttons beginning with Android version 3.67+.

On Android devices, you can map any hardware key as a PTT key. Please note that the talk screen must be in the foreground for the button to work. 

To make this seamless, also allow Zello to unlock the phone and automatically display the talk screen whenever a message is received by going to Options>Behavior>Enable "Show on oncoming message">Enable "And turn on the screen."

To map a hardware button on Android: 

1. Go to the Zello menu>Options>Push-to-talk buttons

2. Tap "+ " at bottom right corner. The following screen displays: 

3.  Press any hardware button on your device to use for PTT. In this example, the Volume down button was pressed: