Good Question, but how do you do it? You have to Create AXL user in Call Manager with AXL Role Assigned and then in Unity Connection you have to configure Call Manager (or any server in cluster running AXL Services) as an AXL Server.
Call Manager Side;
1. First, you have to create User Group name it as ‘AXL_User’
2. Second, Assign ‘AXL API’ Role to this User Group.
3. Create Application User call it ‘ccmAXL’
4. Assign this user to ‘AXL_User’ Group.
5. Now all end users that will be using Voicemail should be also a member of ‘AXL_User’ Group.
Now in Unity Connection;
1. Go to Telephony Integration
2. Click on Phone System.
3. Click on a your Phone system name ‘ in my case its CCME’
4. Click on Edit from Top Menu
5. Cisco Call Manager AXL Server
6. Enter IP Address of your Call Manager or Server Running AXL Service in your Cluster follow by Port ‘8443’ VERY Important.
7. Now Add User details that you have create in Call Manager as an Application User.
8. Now Go to Tools and Sync User with Call Manager or Important User from Call Manager.
That’ it …