Add to the beginning of the OBi100
Physical interface -> Phone Port -> OutboundCallRoute:
{(14085551234<*110110110>):pp},
110110110 is the OBi number of the OBi110
Add to the beginning of the OBi110
Voice Services -> ObiTalk Service -> InboundCallRoute:
{100100100>14085551234:li},
100100100 is the OBi number of the OBi100
If the only rule you have in the InboundCallRoute is ph change it to {ph}
It will now look like this:
{100100100>14085551234:li},{ph}
The above will route the call from the OBi100 over the OBiTalk network to the OBi110 and out the Line Port.
I did NOT test this setup.