Usually the SWAP Partition is being used when the RAM on server is being exhausted completely and we use SWAP partition to carry out the functions.
We cannot free up the SWAP partition when the Call Manager / Cisco Unity / Cisco Unity connection / Presence server / TMS is up and running as some process, might be using the SWAP Space.
How to clear out / Avoid SWAP high usage:
1> Disable any unnecessary/unwanted Traces being set on Server.
2> Increase the physical RAM on the Server.
3> Load Balance the Processes running on the impacted node with other nodes on the cluster
4> Reload of the Server will Clear out the SWAP Partition.
If above information truly helpful please give rating