Plug your OBi 100 into power, Ethernet, and one of your two telephones and boot it up. It should have a dial tone. Turn over the OBi 200 and write down the 9-digit OBi number on the label. Call that number from the OBi 100, prefacing it with **9, like this: **9 xxx xxx xxx
The 200 should ring, and you should be able to answer the call. If it doesn't work, then something is wrong with your telephone, or (unlikely) the ring circuitry in the 200.
If it works, try calling the 100 from the 200 and confirm that the phone attached to the 100 rings.
The goal of this exercise is to determine whether the 200 and its attached telephone are fully working.