Hello guys,
I'm from Brazil, have my iphone 4 just a week and I'm having exactly the same issue. When I call someone or someone call me, the other person can't hear me. The only way to do people hear me is to talk very close to the microphone. So the people can hear me for 1 minute or less... then I've to do it again
I did not let my iphone fall, I did a hard restore, just a restore, I turned off the 3G the wifi... nothing works!
Yesterday I did a 2nd restore and it works for 2 calls and after that started happening again. =/
As all of you... I still don't know if it's an hardware or a software issue but it's really driving me frustrating, cuz I've an R$1300 phone that can't make or receive calls!
I don't know what to do, cuz here in Brazil there's no Apple store. The iphone are sold by the celphone companies and they won't do me a replacement.
I'll try sending to an authorized service an see if can do something for me.
I'll let you know!