We are planning to Implement Attendant console in our organisation. We have 4 Cisco clusters with 2 clusters currently running in 8.6 version and rest in 7.2 version. Soon we will upgrade all clusters to 8.6 .
My query .can we integrate 1 attendant console server with these 4 clusters or we require seperate attendant console for each cluster.
No it cannot integrate to multiple clusters but you probably don't need it to. You can attach it to one and build route patterns on the other three clusters directing calls to whichever cluster CUEAC attached to. Assuming you don't have CCX/CCE deployed you should probably turn on QSIG Path Replacement then too.
The only feature that wouldn't work would be BLF status since CTI Manager isn't multi-cluster. That frequently breaks anyways if the user has more than one phone (it picks the wrong one to monitor) so not using this would likely save you some administrative overhead. Instead, you could use CUP/IM&P, which supports inter-cluster peering across all the clusters, to feed presence status into CUEAC. This would include BLF status within it.
You can get the entire organization, regardless of which cluster they are on, imported into the directory by ensuring that CUCM syncronizes with LDAP at the same Search Base and LDAP filter across all clusters. This way the enduser table in CUCM will have a record for everyone. Note that if you're company big enough that that would overwhelm Informix you can alternatively buy the Premium edition which supports direct LDAP queries as well as a standby server.