How License Pooling Works
If total utilization across all the networked Cisco Unity servers does not exceed total licenses for the feature, the
Whykap : I investigated on this topic and found some information which is License pooling
Cisco Unity server is in compliance with licensing restrictions. For example, suppose two Cisco Unity servers each have 500 licenses for subscribers. With license pooling, one of the servers can use 501 or more licenses as long as the total used by both servers does not exceed 1,000.
License pooling requires that the Cisco Unity servers share the same corporate directory, which stores the license pooling information each server publishes as an attachment to the Location object. Because the pooling information is replicated to other server locations, each Cisco Unity server has the license pooling information it needs to monitor license usage in the pool.