There is a way to get into the service menu on the phone which has been published elsewhere. This morning, a user on cellphoneforums posted this:
For those of you that have not found out how to access your Droid's "secret menu", follow these steps:
Launch the phone application (like you were placing a call).
Dial ##7764726 and press call
The SPC password is 000000 (6 zeros)
Press OK and you're in
Improving your call quality:
Verizon Wireless places some standard settings on the phone that makes it use less of their network capacity and use less of the battery. These settings, unlike in other devices, can be altered in the programming menu. Here's how to do it:
Follow all of the steps (1-4) above.
Choose option 4, vocode
You will see three options: 13K, EVRC, EVRC-B. 13K has the poorest call quality, EVRC has the standard moderate call quality, and EVRC-B has the BEST call quality.
Choose EVRC-B. Your phone is naturally set on EVRC.
Exit the menu
Please note: this will decrease your battery life--the antenna on your phone is amplified.
If anyone out there decides to try this (it won't hurt the phone), please post your reactions and how much it actually improved your call quality.
Seems like you can use it to increase call quality at the expense of battery life. I've not tried this yet as I want to see how much it kills the battery and I don't have a complaint about call quality.