Primary microphone not working for calls

[Tims]

My primary microphone has stopped working for calls. It is not completely silent but just a loud crackling noise which obscures my voice (I have gone to settings/maintenance/check-up/primary to confirm this - no problem with the secondary microphone). However if making a call over Skype, the sound is clear - presumably that uses the primary microphone too?! So feel this is a software issue rather than hardware - I have heard that apps accessing the microphone may cause the problem, but how do i find out which app, and how to disable it (if indeed that is the cause)?

I have already tried taking the back off and manually cleaning the microphone, and re-booting / restarting.

[paulakreuzer]

The official troubleshooting guide suggests the same diagnostic steps you took and then concludes this:

This means something else is causing this problem. Some probable causes of it are listed bellow:

• There is an issue with either your provider network or your SIM card, please ask them to replace it;

• There is an issue with your Internet connection, please make sure to try again with another connection (Wi-Fi);
• There is something blocking the microphone. Talk loudly to your phone and make sure not to cover the bottom part of it.

Point 2 is only relevant if the results were the other way around (normal calls working fine, skype calls have issues).

[maila]

Hi Tim, Skype uses a different microphone than the one in the bottom module, probably because if you were using the front-facing camera for video call, the bottom module mic would not be optimal for receiving your voice. I had the same issue and needed to order a replacement bottom module, after which everything worked fine. Do you use the vibration function consistently? My theory was that the microphone wires have come loose due to strong vibration. Hope this helps, Maila