Well, I tried this but it's not pleasant to hear the music volume decreases on every Viber/Telegram etc message. That's why I'd prefer not changing the volume on messages but stop on phone calls (outgoing or incoming)
Interesting, that when I do an outgoing call Poweramp stops for milliseconds (so it definitely receives smth) but then starts play music even louder. And for incoming calls everything is ok
Surely, I can live with it (stopping music manually before making an outgoing call, but as I tested version 2 and it works ok for outgoing calls (stops music automatically) maybe it can be fixed somehow in version 3?
If needed I can perform any testing for this