Hey guys,
I don't know the root cause for ALL of your phones, but for many phones this is a dust issue. I just moved to a really dry dusty city, and I had a bunch of dust built up in the mic (both the bottom main speaker mic and he noise canceling mic on top of the phone). Here were my symptoms:
- In a call, friends could not hear me speaking.
- If I switched to speaker during the call, they could hear me fine.
- If I used another app (like a video recording app), the audio recorded just fine.
So, in summary, this was only a problem while not in speaker mode and in a call.
I followed the suggestion here:
Cant hear me? In Call Mic (Solution) - xda-developers
I made the five holes on the top of my phone for the noise canceling mic a little bigger. I also took the phone apart and blew air all around the top and bottom microphones. When I put it back together, everything worked! I really hope this helps someone. I have a feeling living in a dusty place will require I mess with this once in a while.
Also, FYI, there was no noticeable dust build up on either mic, but following these steps still fixed the issue.