People can't hear me during calls, and google voice receive nothing (except for a pattern that's always the same whatever sound around the device)
I tried going back to stock firmware, didn't work either. Is there any way to fix the problem or is it time for a new phone?
First I would try sticking a dental pick into the microphone hole, sometimes dirt builds up and can muffle the mic. If it needs to be replaced it is part of the charging block, which is quite easy to replace. RMA if you still have warranty rather than voiding it though.
XDA Developers was founded by developers, for developers. It is now a valuable resource for people who want to make the most of their mobile devices, from customizing the look and feel to adding new functionality. Are you a developer?