Google Voice does forward successfully to Callcentric. Currently, the bug from last year is back, such that caller ID data is getting blocked or sent incorrectly, in the path between GV and certain CC DIDs (their free DIDs from their own CLEC, Telengy).
I'm working on the caller ID issue with Google staff; no promises if/when we can get it fixed.
If you aren't receiving calls at all, forwarded from GV to CC, then try adding some other forwarding phone number, and see what happens. Also, can you reliably receive calls made directly to your CC DID number (not forwarded through GV)? By reliably, I mean, every time, with multiple attempts.