Are you still having issues with Callcentric incoming caller ID or have your moved on? I also am having issues wit their caller ID only showing the incoming number, not the name, about half the time. I filed a ticket and was basically told they had no guarantees of support for the "free" telephone numbers - although I do pay $1.50 for the caller ID service and 911 service. Like you, I have Google Voice with my Obi device and only got the Callcentric phone number for caller ID.
If it is this unstable to provide adequate caller ID, with both name and number, I might want to pursue something else also. Can anyone shed light on this issue?