I'm looking to use pjsua with a raspberry pi configured to auto-answer calls and output audio over the jack however since there is no audio input on the Pi it fails with the error PJMEDIA_EAUD_NODEFDEV I have tried --null-audio (but this affects both directions) as well as trying to specify just the --playback-dev attribute which seems to result in the same error. Is there any way to achieve this ? Any advice you can offer would be much appreciated Regards, Ross