Comment 66 for bug 1544477

@Anupam: interesting, once the issue reappears could you also try to post the output of the command (as user) 'pactl list sink-inputs':
- as soon as you unlock the phone
- as soon as you type few digits in dialer-app (step 4 of my previous comment)
This could tell us if the issue is about roles switch (maybe the muted feedbacksound role gets wrongly used, it should be active only when not-playing audio)

3 (again) - Do you play any mobile game (or any other app installed from store which uses audio)? (sorry, I forgot to mention this in my original question). An app using multimedia role constantly in background could cause the issue I found in indicator-sound.