If you are making a FaceTime call on your brand new iPhone 6, and the other party is not able to hear you properly, it is quite likely that you have not taken the plastic wrap off the phone. The noise cancellation microphone between the camera and the flash is covered with the plastic wrap on a new iPhone 6. This causes the iPhone’s noise canceling algorithm to malfunction when you make a FaceTime call (or any call with the speakerphone on).
In order to fix this issue, just take the plastic wrap off, or, if you don’t want to take it off until you get a case (totally understandable), use a sharp pin (very carefully) to punch some holes in the plastic wrap over the microphone. This should not obstruct any audio waves from entering the microphone and the noise canceling algorithm can do its magic.
