Like N7AS said, the OBi200 only supports 1 line.
You could use the OBi100 for a 2nd line.
You can route outbound calls from the OBi100 to any trunk on the OBi200.
You can also route any inbound call on the OBi200 to the Phone Port on the OBi100.
If your 2 line phone has a single cord you would need a splitter to connect it to both boxes.
Post a reply if you are interested with this configuration.
In your post include your requirements.
Edit:
I was curious of what you said about dial tone on your 2nd line of your 2 line phone.
I don't have a 2 line phone, but I plugged a 2 line splitter into my OBi200 and the 2nd line was dead.
Are you sure you have a 2 line phone or do you have a single line phone system with 2 handsets?