If InboundCallRoute for the LINE port is set to (blank), then incoming calls from Ooma will be ignored by the OBi.
If you set PrimaryLine for the PONE port to SP1 and leave the OutboundCallRoute at its default value, then normal calls will go via SP1, 911 calls will go via Ooma, you can press # to get dial tone from the Ooma, and numbers prefixed by **8 will go via Ooma.