Call Sound weird on Mi2s

Dec 6, 2013
Hello friends,
Im new to the forum and Xiaomi phones =)
I have bought a Xiaomi Mi 2s phone recently from china and put the international Miui rom on it.
I like it much better then the regular android versions or CM (I had a Galaxy S2 with CM before)

I have encountered a very strange phenomenon on it:
When im making a call to someone and we are talking at the same time (not just im talking and he listening or hes talking and im listening, we are talking at the same time) my voice from xiaomi gets distorted to the other side but i can hear the other side very good.

It is very hard to understand me.
if we argue and talk simultaneously, I can understand the other side but im very distorted on the other side.

I have tried to flash the Original MIUI (chinese) and the latest international miui.
I dont want to use different roms because i like miui.

Anyone saw this king of bug?
(I have a friend with xiaomi phone too and its the same with his phone so i guess its not a hardware issue)

Thanks for all,