@ArashMiniStar and everyone else who have problem with low volume in calls.
You have to edit one value in mixer_path.xml.
This file should be in system>etc or system>vendor>etc.
Then find "ear". It should be the last result.
There will be line:
<ctl name="RX1 Digital Volume" value="84" />
Change this value to 93 and reboot phone.
i cant find ear value!
but i changed "handset" and other "RX1 to 5 Digital Volume and it worked !
thanks a lot my friend