From the book..."ACPU software versions prior to 7.0, PRI supports AT&T Custom ISDN only. Beginning in software version 7.0, PRI supports National NI–2, DMS–100, and AT&T Custom ISDN. This support also requires firmware version PRI–1.10x02, or higher, on the ISDN PRI port card. Order part number 440152 to upgrade the firmware on older PRI port cards."
Mike