i have an avaya ip406 with two expansion shelves giving me sixty odd phones. I also have another shelf with isdn lines on it but this seems not to work. On the bottom unit it shows that the expansion shelves for the phones are connected but not the one for the isdn shelf (plus on the isdn ports they are all orange). I have checked all cables and connections and they are correct, but i am not an Avaya geek in the slightest. Does anyone know of any commands i can type in/look at to find my problem.