Here is your fix to the call quality issue that some people seem to have.
https://supportforums.motorola.com/thread/17480;jsessionid=74438F24B440BBAFE28A963765ACB22D.node0
##7764726 (##PROGRAM)
CALL Button
Enter SPC Password - 000000
VERIFY
04 Vocode
Select EVRC-B
This fixes the sound quality issue (assuming your problem isn't related to something else).
This actually takes you to the PROGRAM menu and you will be able to switch back and forth between 13k, EVRC and EVRC-B. So you aren't making a chance to your phone that you can't reverse. The phone will reboot after you make the change.
I'm not having any issues with call quality, but I went ahead and made that change just for the hell of it. Mine was indeed set to EVRC - the older tech.