No, extensions were implemented over the summer.
http://www.callcentric.com/new/I read your post several times, and I guess I am stumped now. I tried to post a screenshot of my Callcentric extension routing page, but the Obitalk forum posting system said the attachments folder was full. WTF.
Anyhow, if you place a call to your GV phone number from some unrelated phone, and you see the inbound call in your GV account's history on your GV account's web page, and you see the inbound call show up on your CC account's log of calls (as Anonymous), AND you haven't blocked CC from ringing your extension (and I think you've confirmed all that), then it ought to ring your OBi-attached phone. I hate to say it, but perhaps you should try resetting your OBi to factory defaults, as you might have done something to your configuration to cause this behavior.
Right now, my OBi-attached phones (and my IP phones) ring when the anonymous calls come in via the free DID, and (of course) they ring when calls come in to my other GV number via my paid DID, with Caller ID. So, "anonymous" caller ID shouldn't interfere with calls being received on the OBi-attached phone, unless you have a configuration setting causing it.
BTW, thanks for your support over on the GV forum thread. I gave up debating that guy -- people get blinded by "I deserve free beer for life", and it's just hopeless.