Sure, you can forward to Callcentric from your OBi by putting the forwarding SIP URI address in the X_InboundCallRoute field (under Voice Service) for the trunk you wish to forward. But you would need to use the following address format:
1777XXXXXXX@
in.callcentric.com
Not sure what your goal is for doing this but keep in mind you won't get CNAM going this route. CC doesn't support CNAM for SIP URI calls whereas an ITSP like
VoIP.ms does.
Edit: CC does support CNAM override for SIP URI calls so if the incoming number has an entry in your CC phonebook then you will see the name you associated with that number.