[Q] New/Other Radio Xperia V topic

I'm having lots of problems while calling, I can hear the person on the other side of the line perfectly while they can't hear anything I say (I sound very far away from the phone). This makes it impossible to have a normal conversation with anyone.

I understood flashing a new Radio could solve this problem, now my question is:

Where do I find these radio's and which one should I flash (Xperia V 4.3, The Netherlands)?