The OBi uses "bridging" to mean connecting an inbound call to an outbound one; that's not the same as conferencing. For example, one might set the InboundCallRoute for the LINE port to ring the PHONE port and also (via a SIP provider) ring your mobile phone. But, when you answer from either the phone port or the mobile, the other outbound leg gets cancelled; no conference is created.
AFAIK, there is no way to create a conference on the OBi, other than by sending hook flashes on the PHONE port.
You could, of course, configure the LINE port to bridge to the PBX at your data center, which could be programmed to send an outbound call back to the OBi, which would ring the PHONE port. The PBX could then record the call. However, this would add latency and may reduce reliability. If there is an ocean between the locations, I wouldn't recommend this approach.