change voice codec from EVRC to 13k on Sprint Mogul

To me the voice quality improved by quite a bit when I switch the codec from EVRC to Voice 13k on my Sprint Mogul. Below is the steps on how to switch.

1. On the phone screen type ##786# and write down the ESN(Hex) Value
2. Search for MSL Generator
3. Use the MSL generator to obtain the unlock code by entering the ESN value in step 1 (need to be all CAPS)
4. On the phone screen, type ##778#, select Edit, and enter the unlock code obtained in step 3
5. Click on View Info at the bottom, select CDMA Settings, and change all the codec from EVRC to Voice 13k
6. Reboot.