First we need to do a bit of information gathering. n8x0 or n900? Connection type? What types of calback numbers did you have before (Gizmo, cell, landline, etc)? What was the previous success rate for each kind? What was the success rate with google.com/voice and google.com/voice/m? When "it doesn't connect" is Dialcentral giving an error or is the connecting failing silently? Is there any kind of sign in your GV or phones call log that an attempt was made? The above paragraph of questions again for the new release.