ADTRAN user manual The Express L128/L128T software setup The Express L128/L128T hardware

Chapter 4: Troubleshooting

probably something wrong with the translation of the line. The phone ser- vice provider should be able to help.

3.If the PWR LED still flashes, there is a physical problem with the phone line (more than likely, a problem with the Layer 1 setup). The problem is in one or more of the places listed below:

•The Express L128/L128T software setup

•The Express L128/L128T 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.Ensure the line is plugged into the Express L128/L128T connector marked ISDN on the back of the Express L128/ L128T.

B.Make sure the Express L128/L128T is configured for Dial line service.

C.If possible, try another piece of functioning ISDN equip- ment with a U-interface on the line.

D.Talk to your service provider and ensure you have an ISDN Basic Rate U-Interface with 2B1Q line coding. (Wrong options are an S or T interface or AMI line cod- ing).

E.Ensure that your phone line is connected to the actual telephone line (U-interface) provided by your telephone company. Make sure your line is not connected through another piece of equipment such as an NT1 in a wiring closet.

F.Make sure nothing else is bridged across the line pair.

G.With a minimum of extra wiring, try connecting to the line pair at the point where the service provider’s wiring ends.

108 Express L128/L128T User Manual 61202.070L1-1