I'm having a similar issue. I got a new phone, GV integration seemed to be broken after that point, so I removed the phone and attempted to re-add it. Removal seemed successful, but now I am unable re-activate it. It says it's calling my phone but nothing ever goes through. What's worse is when attempting to call my phone from other GV accounts, I recieve the following message:
We could not complete your call, please try again.
I'm assuming that this is what the activation call hears but I cannot confirm. I've attempted to get help from Sprint, but they don't have any idea what's wrong. My Sprint number/number I'd like for GV ends in 8505. Any help would be appreciated.