If you are using an iPod, the RSM-30 may shut down automatically when Zello is in the background. Set your RSM to self-powering mode to prevent it from shutting down.
1. Unplug from device.
2. Press MTF button (button on the front) for about ten seconds.
3. You'll hear one set of tones that tell you the battery status.
4. The second set of tones puts the device in self powering mode.
Watch this video to listen to the tones: http://youtu.be/dwkMLWAZ04o.