Blaine – welcome to the forum.
First make sure that your OBiON / softphone number has your OBi device number as its Voice Gateway. Click on your softphone number (290xxxxxx) in the OBi Dashboard to do this.
You don't say which OBi model you have, but that should not matter for most of this answer. Here's the simple answer:
Delete any existing rules in the InboundCallRoute and replace with:
Voice Services > OBiTALK Service > InboundCallRoute:
{(290123456)>(Msp2):sp2}
Where 290123456 is your OBiON softphone number. Any calls coming in from 290123456 will be processed through the sp2 DigitMap and be sent out on the sp2 trunk.
Voice Services > SP2 Service > X_InboundCallRoute: {}
Incoming calls will get "fast busy" no phones connected to the OBi will ring. If all your calls are forwarded in GV to your cell phone, then I guess they will never get to the OBi anyhow.
A more useful OBiTALK InboundCallRoute might be:
Voice Services > OBiTALK Service > InboundCallRoute:
{(290123456)>(Msp2):sp2},{(290123456)>(<**1:>(Msp1)):sp1},{(290123456)>**0:aa},{(290123456)>0:ph},{ph}
Normal numbers are still routed through sp2.
**1 followed by a number gives access to sp1 trunk (in case of sp2 failure).
**0 gives access to the OBi auto attendant.
0 rings the OBi phone port (direct call to home).
{ph} is there for other OBi numbers calling your OBi at home.
Make changes via the Obi Expert Configuration pages. From your OBi Dashboard, click on your OBi number and follow the prompts to get there. To change a value uncheck both boxes to the right of the value and leave them unchecked. After changing the values on one page, press submit at the bottom of the page and wait a few minutes for the Obi to reboot. Then move on to the next page if required.