I'm running Zoiper (1.30) on my Nexus 6 (Android 6.0.1). I have a Plantronics M55 Bluetooth headset. The headset works fine for normal phone operations.
But when I use the headeset with Zoiper, I'm able to hear the other party's voice, but my voice is not transferred. So I have speaker functionality on the headset, but not microphone.
Any idea what I need to change to get this to work?