The reason I asked about whether or not calls would correctly forward to a regular number (vs. just Chat), is that you specifically said that the GV account hosting the newly-ported number was only set to forward to Chat. You didn't mention that you had tested it already with another forwarding number.
As to your question about why it mattered, since outbound calling works: that's not how VoIP works. Outbound calling is provisioned and operates separately from inbound calling. When a number is ported, the gaining carrier first provisions your service to make outbound calls using their trunks, and displaying your number's caller ID. This is completely independent of routing inbound calls, which involves the carrier working with
NPAC to assign their phone switch LRN to your number, so inbound calls know which switch to send the calls. This can take another day or more, and it can get screwed up royally when people immediately port from the second carrier to the third carrier.
There is no need to make that inbound call route setting. Making arcane changes like that, only causes problems down the road, exactly like you just experienced, when people don't recall that they changed something in the past.
The correct way to use Callcentric with Google Voice and an OBi, is to remove the check mark to the left of Chat in your Google Voice settings, and only have a check-mark next to the Callcentric number. Google Voice only forwards to check-marked destinations. Outbound calling is enabled by simply having Chat added to your GV account, and inbound calling is enabled via the check-mark.