I was able to fix the echo issue with the PinePhone on Mobian by using alsamixer and pressing the F6 key to select the hardware (or use the command "alsamixer -D hw:0"). Then I changed "Mic1 Boost" from 64 to 0 like mentioned on https://forum.manjaro.org/t/original-pin...ing/153873. Decreasing "Line Out" from 100 to around 50 also helped (this setting decreased the loudspeaker volume which was not working with the volume keys during a call).
I noticed the "Line Out" setting is reset to 100 every time we enable the loudspeaker so a quicker way to reset the setting is to use this command (note that in order to display "50%" in alsamixer, I had to use "60%" in the amixer command):
amixer -D hw:0 set "Line Out" 60%
To permanently set "Line Out" to 50% on the original PinePhone, we can edit /usr/share/alsa/ucm2/PinePhone/VoiceCall.conf and change the appropriate setting (in a similar way to what was explained on https://forum.pine64.org/showthread.php?...#pid111246).
I also had a black screen during the first call after boot, even after disabling the options "Dim Screen" and "Screen Blank" in Phosh power settings. A workaround is to call the voicemail and the screen will not always be black after a few seconds so we can end the call. However the issue comes from the proximity sensor, which can be disabled by adding "blacklist stk3310" to a file like /etc/modprobe.d/blacklist.conf (https://forum.pine64.org/showthread.php?...#pid111765).
In my case, calls were only working when pipewire was not installed and only in 3G, not 4G (https://forum.pine64.org/showthread.php?tid=16943).
I noticed the "Line Out" setting is reset to 100 every time we enable the loudspeaker so a quicker way to reset the setting is to use this command (note that in order to display "50%" in alsamixer, I had to use "60%" in the amixer command):
amixer -D hw:0 set "Line Out" 60%
To permanently set "Line Out" to 50% on the original PinePhone, we can edit /usr/share/alsa/ucm2/PinePhone/VoiceCall.conf and change the appropriate setting (in a similar way to what was explained on https://forum.pine64.org/showthread.php?...#pid111246).
I also had a black screen during the first call after boot, even after disabling the options "Dim Screen" and "Screen Blank" in Phosh power settings. A workaround is to call the voicemail and the screen will not always be black after a few seconds so we can end the call. However the issue comes from the proximity sensor, which can be disabled by adding "blacklist stk3310" to a file like /etc/modprobe.d/blacklist.conf (https://forum.pine64.org/showthread.php?...#pid111765).
In my case, calls were only working when pipewire was not installed and only in 3G, not 4G (https://forum.pine64.org/showthread.php?tid=16943).