Step 1. Dial ##7764726
Step 2. Enter 7 0's as the password (Zeros) Verify.
Step 3. Select 04 Vocode
Step 4. Select EVRC - B
Step 5. Apply and Phone will reboot.
This use to be a call quality hack on Froyo, Gingerbread has omitted this, any ideas out there on a work around?