Over on XDA, seems spaciorek has figured out how to change the voice codec from EVRC to EVRC-B. For definition, go here.
Enhanced Variable Rate Codec B - Wikipedia, the free encyclopedia
I've tested it out and callers say I sound much better and don't sound distant anymore
EVRC-B Access - xda-developers
**772
SPC code 000000
The bottom of the screen will have buttons that are directional like a d-pad.
Press down until you see:
SVC Mode NAM1
End of BASIC NAM
Exit
Press right once you will see EXIT change to MORE
Hit enter
Press Down once and you will see:
HomePage VoiceSO
EVRC
Push right button to change to EVRC-B
Hit Enter
Phone will reboot.
Hit Enter after each change to stay to EVRC-B.