I helped someone with a Yealink T46 and an OBi110 here:
http://www.obitalk.com/forum/index.php?topic=7323.0You can't register an IP Phone to an OBi110.
The T46 sends its IP Address instead of the UserID.
Maybe this is the cause of your problem if your model is doing the same.
Setup the OBi202 for no registration
X_Proxy: unchecked
Everything else should be the same.
To route inbound calls to the Yealink
ph1,ph2,sp4(anything@xx.xx.xx.xx:pppp;ui=$1)
xx.xx.xx.xx:pppp is the IP address and port of the Yealink.
The Yealink must be able to call with registration.
I think there wasn't an option on the T46, but the user was able to call out after registration failed.