I had (and I still have) problem with my phone, a Samsung Galaxy S3. Sometimes people hear me bad or doesn't hear me at all and this is a real vexing problem.
I brought the phone in a Samsung authorized center, they said me that my OS version (a Jellybean branded by H3G) could be bugged. They've replaced it. Now audio problem is still present and as if that weren't enough my phone freeze it's screen at least seven, eight times per day (I have to detach the battery to recover this issue).
I have installed a software to record my phone call, I have listen again every phonecall in which my interlocutor said that he doesn't hear me and... my voice is perfectly audible in registered phonecall.
I always thought that my microphone was defective but at this point I'm not so sure of this assumption. What can I do? I have no idea about the problem, could a non-branded Jellybean version resolve the problem? Could samsung completly replace my phone?