Chosen Solution

My mind is absolutely boggled. I’ll try to make this short. I have an iPhone 6 Plus. Both microphones seem to work perfectly fine (I’ve tested the bottom microphone with Voice Recorder– super clear. I’ve tested the top microphone with Siri and Voice Dictation, understands me every single time) HOWEVER Whenever I make a phone call with this phone, the person on the other end cannot hear me whatsoever. This is not a matter of being muffled, this is literally no sound at all. The only sound that comes through sometimes is a crackling noise, almost like ruffling a bag of chips or something. How can both of the microphones work perfectly fine but then completely not work only during phone calls? Anybody know what is going on?

Actually, there are 3 microphones in the iPhone. The bottom microphone is for Voice Memo and phone calls. The other microphones serve as error cancellationThe (top) front microphone is used for FaceTime calls and selfie videos with the front camera (FCAM). The top back microphone serves as error cancellationThe (top) back microphone is used for videos with the rear camera (RCAM). The top front microphone serves as error cancellation Have you tried with the Apple headphones? You may still have a defective bottom microphone or more specifically a partially defective Lightning Jack. I would try changing it to see if that helps. Otherwise, there may be something wrong with the audio circuitry that only kicks in when doing phone calls.

Qualcomm WTR1625L RF Transceiver Or Cirrus Logic 338S1201 Audio Codec? But it sounds a lot more like a software thing. Maybe a backup to restore? Whatchu think, bro? @refectio

Like @theimedic said, devices using iOS 10 are prone to a sound bug that was supposedly fixed in iOS 10.2.1. So if you are not yet at 10.2.1, update or even better DFU restore. If you still have an issue, it could be the two transceivers. It would be a board level repair. I suspect it would be the Qualcomm WTR1625L RF Transceiver also mentioned by iMedic. However, a detailed history of the phone can help narrow down the issue.

We’ve seen this same issue recently with a iPhone 6. The microphones would work fine in voice memos and other apps, however on a phone call the microphones ceased to work. Our solution was as follows

  • Remove board
  • Remove the shield on the back of the board at the top, the one that just peels off
  • Connect a temporary charge port, battery and screen and turn on the phone (plug in charge cable to turn it on)
  • Make a call to another phone that you have, put on speaker phone.
  • Whilst in call lightly apply pressure to the U1202 Power Management IC, the shiny one with a Apple logo.
  • Talk into mic whilst applying the pressure, the mic may start working or you may hear crackling noise. If it does you know that this chip is probably the culprit
  • Reflow the U1202 chip and test again, it may just work. We tried the above and it fixed this exact issue.

I had similar problem with my iPhone 6s. Aside from voice memo and video recording, normal phone call and FaceTime worked, but 3rd party app video & voice calls didn’t. I plugged in my EarPods and it worked! I removed the pods and tried again, and it worked! So I think the problem was the iPhone somehow thought that an external microphone was connected and therefore muted the built-in one. The static/crackles we experienced might be the iPhone trying to draw voice from unoccupied audio port. Me plugging in and then removing earphones might have triggered “microphone removed” event in the iOS and thus re-enabled the built-in microphone. I hope this helps, if not you then someone else who are having similar problem.

Just in case, clean the audio jack.. Sometimes it solves that problem

It’s a virus that’s stored in your backup. Get an exchange and don’t use a backup from iCloud, it’s a pain but it’s the only way.

The problem was intermittent so it’s hard to be sure but I haven’t had anyone not able to hear me so far. Limited voice phone use at the best of times so not enough use to declare 100% success. But early returns look good!

I solved same issue on my phone by going on General, settings,resetting only the network settings.