Before we can configure Automated Alternate Routing, we must ensure it is enabled in the system.
To enable Automated Alternate Routing, perform the following:
First, activate the necessary services for AAR (System | Service Parameters).
Select a server from the Server drop-down menu. This should be a server running the CallManager service.
Select the Cisco CallManager service from the Service drop-down menu as shown in the following screenshot:
After selecting the CallManager service from the drop-down, and the page reloads, the associated parameters are seen.
Near the bottom, under the section titled Clusterwide Parameters (System | CCM Automated Alternate Routing), change the Automated Alternate Routing Enable Required Field to True, as shown in the following screenshot:
Click Save.