PLEASE HELP: Sound transmission problem while calling

Jan 14, 2013
Hi everyone,
since I updated to MIUIAndroid 3.3.22 from 3.3.15 I started facing the following issue: when answering an incoming call, there was no sound transmission: neither could I hear nor be heard at the other end of the line, although the phone call kept on. Exactly the same started happening while making an outgoing call.
At first I thought that it was caused due to poor signal, so I tried different – almost all available – radio basebands, but without success. Then, I thought that it was a bug, so I wiped everything and started flashing other MIUI versions, always v5, the stock Android ROM and other ROMS, like WIUI etc. but again without success.
What I’ve noticed during this whole month that I am having this problem is that it must have something to do with the proximity sensor, because while I am speaking on the phone, I might lose the sound either when I activate the loud speaker (that’s how the problem first appeared) or when I just take the device away from my ear, causing the proximity sensor to turn on the screen. But that’s not always the case. And the other strange thing is that if I receive an incoming call and cannot speak due to this problem, if I turn on and off the loud speaker, that might fix temporarily the sound problem. If not, I have to turn off and reboot the phone to make it function again properly. And finally, the problem may appear in one call and disappear on its own in the next call within minutes or even seconds.
As you understand, I feel confused, tired and disappointed because like the phone very much and want to enjoy it as I did until one month ago.
I welcome any ideas that could help me tackle this issue.
Thanks for listening