The CTI interface to the AACC was not completed. The configuration was only mirroring the physical telephone.
Based on AACC's "Call Redirection with Avaya Aura Contract Center Application Note", Section 12 Appendix F - ' CLID not appearing on Transfers'
In Avaya Aura® Contact Center the customer's Calling Line ID (CLID) is made available via the CTI application (i.e. AAAD). This can be used to drive screen pops or customer history lookups.
If the agent is using a physical phoneset then a CLID is also available here. However for contact center calls the CLID that is displayed on the agent's physical phoneset will be he CDN number that was used to queue the call, and not the customer's CLID. "