I have an issue with my iPhone 6. When I call people and use the phone next to my ear, the mic does not pick up anything and my voice is not heard. However if I put the phone in speaker phone mode, the mic works and the person at the end can hear me well. It seems it stops working only when I put my ear up to the proximity sensor and the microphone switches? It does not work then.
This phone has had its screen replaced and that's about it.