I've been having a recurrent problem with my iPhone 5. Often, my sound gets muted (the mute button has not been pressed) so whoever I am talking to can't hear anything on my end while I can clearly hear them. Sometimes it seems to cut in and out for them, and sometimes it's continuous until they hang up. Also, I often have a low-pitched thumping/buzzing sound coming in my phone that is super annoying - I can hear it, but the person on the other end cannot.
I assumed it was my phone so had it replaced, but there has been no improvement. Has anyone else had this same issue??
the light sensor aka the screen sensor is most likely not activated properly & when you put your cheek on the screen, it will most likely mute or press other buttons. If you google it, this happens with EVERY device with a touchscreen on them.
As for the buzzing sound, the only time i hear that is when i am near a TV or tower causing the waives to do this. I would call Apple support & see what they say about this.