Epage,
The no call back on a gizmo phone might not be your issue but a google voice one. I just attempted to make a call back via dialcentral and it failed a few times to ring me. I then attempted a few times from the mobile site and fail again! I then sent the request through the main site and bingo, call rang through. What does this mean? I have no idea, just wanted to share my experience from about 20 mins ago.

I am using gizmo simply because I have one and figure it should be most compatible with Google voice, however I also have a sipgate account. Should I maybe think about switching my call back to this instead or will the call back issues persist?