We route voice traffic bewteen our 2 facilities (in 2 states) over a T1. On our end, we have a Lucent System 85 PBX. From there, though a NorTel DE-4 Enhanced channel bank to the CSU. I am in local alarm on the channel bank, and amber alert on DTE on the CSU. If I put the channel bank in loop, all 24 4-wire E&M cards busy out. But a sI try to route traffic through them (by repeatedly attempting place calls) only 6 of the E&M cards light. (the same six in succession) I have done this "test" (poor choice of words I guess) in the past, so I know that if you make at least 24 attempts, you will light each of the 24 cards. So why would I only be hitting 6 out of 24? I have a bad feeling its the PBX (Which Lucent no longer supports) I can find no-one that knows anything about either the PBX or the channel bank. Could someone offer some ideas to a desperate Facility Engineer? Thanks.