The "Check Tel Line" on the phone means that it is not seeing the 50 volts that it should from the OBi. Nothing to do with the internet, your LAN or the OBi's configuration settings. Often it is simply that the phone cord is unplugged or faulty. However in your case it sounds like you have additional problems which could indicate that the OBi box or its power supply is faulty.
What account and what exactly do you mean by "my account registration is not working"? What is giving you that information?
