Hi guys, I have an iphone 4 and I noticed that when I insert the speakerphone, the other party can not hear me completely. But when I call normally, the other party can hear me perfectly. I did some more tests: I made a video and audio can be heard. I tried to start a communication with FaceTime and the other party can not hear me. The Skype audio, making video, works. If you register with a voice memo function, the audio can be heard. I know that the microphones in the iPhone 4 are two, one below and one above, the problem that concerns precisely? Precisely that the iphone I bought it from a friend because he had a problem with the motherboard, and it is not under warranty, I replaced it myself. I do not know if before the microphone work or if I have done some ******** me, even though I do not think. My friend says that before the microphone worked, but I do not know how much I trust him ...!