The best test is to connect an unpowered/corded phone to the OBi.
With the OBi reset to factory defaults and with nothing but a telephone connected to the PHONE Port, you should have dialtone and should be able to reach the Auto Attendant by dialing **0. Once in the Auto Auto Attendant, you should be able to select option 3 and a phone number of 0#, and the OBi should ring your telephone after hanging up.