Recently I started to notice that a lot of people who call me, can't hear my voice during the call.
The phone is an almost 2 years old Sony Ericsson Xperia X10 mini pro, so I guess the microphone could just get old and somewhat start to fail.
Also it could be wrong from the beginning. I didn't had that much calls until recently. I think noticing it just now might be reasonable.
According to my experience the problem only occurs during incoming calls, I've never experienced it while I called somebody. And only in the first incoming call, if I was recalled right after the first call, everything was fine. This makes it look like if it is the provider's issue.
And of course some app blocking my microphone also came into my mind, but I don't have many installed and I don't know if any of them would do such a thing anyway. (The phone was never rooted, it has the official 2.1 ROM, etc.)
The question is: because I still have some of the warranty left... how could I determine if my problem is a hardware problem, a software problem or a provider problem to know where should I go with it? (According to my experience if I just say something is wrong without hard evidence, the repair service and the provider will only try to make the other take the blame. Not to mention that they will factory reset the phone, say that they couldn't reproduce the problem, so it had to be one of my apps.)