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Chapter 11. Troubleshooting
2.Disconnect the ISU 128 from the ISDN line. From a functioning voice phone, call the local directory number(s) provided with your line. Calling a good ISDN line with nothing connected usually results in a ring or fast busy tone. If someone answers or a
3.If the ISU 128 continues to read Link Down, there is a physical problem with the ISDN phone line (more than likely, a problem with the Layer 1 setup). The problem may be one or more of the following:
•The ISU 128 software setup
•The ISU 128 hardware
•The wiring on your premises
•The telephone service provider's wiring
•The telephone service provider's hardware
•The telephone service provider's software setup
To isolate the problem, perform the following procedure:
A.Make sure the ISU 128 is configured for dial line service. Check that
CONFIG, Netw. options, Dial Line, is selected on the menu.
B.Try another piece of functioning ISDN equipment with a
C.Talk to your service provider and ensure you have an ISDN Basic Rate
D.Ensure that your ISDN phone line is connected to the actual telephone line
E.Make sure nothing else is bridged across the ISDN line pair.
F.With a minimum of extra wiring, try connecting to the ISDN line pair at the point where service provider's wiring ends.
78 | ISU 128 User Manual |