If the Audix is a slim (single slot) the max ports is 12. The 5 slot (yes I know it is only 4 slots wide but one is reserved for cooling)the max is 16. The Avaya TSO would have to dial in and activate the addition ports on the DefAudix. If the integrafion type is DS mode, ports on the audix are programed as sets, you would need to add the additional ports (sets or lines depending on your view).
Thanks
Chris