Normally, if you configure your softphone with your OBi device number as its gateway from your OBi Dashboard, then OBiTALK will automatically put your softphone number in your Circle of Trust. However, it does not list it there! You should see something like this:
Voice Services > OBiTALK Service > InboundCallRoute:
{290111111>(xx.):pli},{290111111:aa},{ph,ph2}
"pli" will actually be whichever service is your Primary Line. This means that if you dial any digits, then they will be sent out of your Primary Line; if you dial no digits the call will go to the Auto Attendant.
The InboundCallRoute can be made to be much more flexible, but that's for another post.