I've heard lots of report of the app failing due to Google's API change. I'm sorry if it has affected you, but here are why I'm unable to fix it for the moment:
- The Google Voice API is not public - that is, Google really does not (yet) intend for outside developer to use the Voice API, and that means it could break anytime without warning.
- Google might have rolled out some changes, but as typical of Google, it does not roll out change to all its user at once, but instead gradually. My own Google Voice account has not been affected by the change, so I don't know what has been changed. And I have no clue how to fix the problem if I don't know what has been changed.
- Real life commitment. Sorry I do have a life beside programming - a busy one at that especially near the end of the semester in college.
Just be a bit patient...
Quick note: According to some, this is a temporary problem from Google that has been solved. If Google Voice Callback has worked for you in the past, but stopped working recently, could you give it another try to see if it works now?