Post originale di: iPhone 3GS KING ,
The iPhone 6Plus has 3 microphones 1. In the earpiece which is used for voice memos and face time calls 2. One on the back of the phone which records audio for videos 3. On on the bottom of the phone next to the headphone jack to make calls. The fix. Make sure those holes on the bottom of the phone are clean, if they are and you still have the same problem, replace the charger port on the bottom of the phone. The part is fairly cheep.