1, What is the process step after customer receive 3&3 PAK?
2, Does there have any doc. to discribe how to process after the customer receive the PAK?
3, My customer had purchased 700 3&3 users (Upgrade ala carte CM to ENH USR, 1 User), when they apply licenses using the PAK, they get only 1400 DLUs, but their phone is 7961/7975 whcih request 4/5 DLUs. How can they get the old DLUs back?
Your current DLU are perpetual and would have moved if you had used DMA. You could also manually request them from licensing based on the typpe of phones you have. You only get 2 DLU using 3x3 to turn up single number reach. The assumption is that your current DLU will be moved from the original cluster
Is there any "official" document by Cisco on the 2 DLUs for 3X3 Promo and necessary to re-host the existing DLUs to a new CUCM Publisher server.
There is no official document specifically regarding the 2 topics you mention above. Both follow standard Cisco license entitlements and deployment guidelines (e.g. hosting licenses on CUCM Publisher).