Was having the exact problem described in this link trying to get my Google Voice account setup with the Google Voice App on my Incredible. Been trying, failing, and searching for days. Stumbled on this today and it fixed me right up.
Android Google voice app will not verify phone (used to work on previous Android phone) - Google Voice Help
The answer from from "mbligh" is:
"I fixed this. I think it's Google's "interesting" login management, where though you have one email address, it can be multiple accounts on the backend
If you're foo@bar.com and it asks you which account you want to use and that's one of the options, pick "other address" and type foo@bar.com again and your password. Now it works.
Makes absolutely no sense whatsoever, but still."
Android Google voice app will not verify phone (used to work on previous Android phone) - Google Voice Help
The answer from from "mbligh" is:
"I fixed this. I think it's Google's "interesting" login management, where though you have one email address, it can be multiple accounts on the backend
If you're foo@bar.com and it asks you which account you want to use and that's one of the options, pick "other address" and type foo@bar.com again and your password. Now it works.
Makes absolutely no sense whatsoever, but still."