@libremax
Thank you for info

@rudi-timmer
Thank you for info! Still have my old googlefied Motorola I'm sure it is suddenly fixed

Recently installed Ubuntu Touch on my Fairphone 4.
Seems like either microphone nor speaker is activated during call.
Rolled the phone back to standard android, all is ok.
Reinstalled Ubuntu Touch, no sound.
Tested both speaker and microphone with other apps. They work.
The fault seems to be connected to phone application and is replicable.
Can anyone point me in a direction where to look?