Can't hear phone calls from Iphone6

[iMore Question]

If I call a phone, the call will go through on both ends. However, I can't hear who I called and they can't hear me. Everything looks normal (all the circular buttons are white and the time is counting). It also doesn't work on speaker.
After this starting happening, I tried all of these to no avail: 1. I can listen to voicemails through the normal earpiece, very clear, no issues. 2. I can listen to music on my speaker. 3. I can record my own voice, so I know the microphone works. 4. I've turned wifi off, and the network works just fine without it. 5. The problem persists both before and after I updated the iOS, twice. The problem has happened in iOS 7, 8, and 9. I am in Hawaii right now and some people suggested me places like TCAWireless as the best place here. I don't know what to do. Any help would be appreciated!

 

[Lynk12]

have you tried what I like to call a hard reset hold the power and home button down till you see the  logo

 

[Larry Cook1]

Try going to your phone app and tap on the keypad. Put in ##update# and hit talk. It will say it is running a test, it will say test completed and hit ok. This cleared the problem for me.