/mcpDescription Field This field applies to unregistered external DN calls. The calls are rerouted to a specified destination or voicemail. Note You must also specify the maximum number of forwards in the Service Parameters Configuration window for a directory number in the Max Forward UnRegistered Hops to DN service parameter. This parameter specifies the maximum number of forward unregistered hops that are allowed for a directory number at the same time. This parameter limits the number of times the call can be forwarded due to unregistered DN when a forwarding loop occurs. Use this count to stop forward loops for external calls that have been Call Forward Unregistered. Unified Communications Manager terminates the call when the value that is specified in this service parameter is exceeded. Forward Unregistered External This field specifies the seconds to wait before forwarding the unanswered call to the Call Forward No Answer destination, if specified. Make sure the value that is specified in this parameter is less than the value that is specified in the T301 Timer service parameter. If the value in the Forward No Answer Timer service parameter is greater than the value that is specified in the T301 Timer service parameter, the call is not forwarded and the caller receives a busy signal. Leave this field empty if you want to set the value in the Cisco Unified Communications Manager Forward No Answer Timer service parameter. No Answer Ring Duration (seconds) Enable Destination Override for Call Forwarding Enable the destination override for call forwarding, Unified Communications Manager ignores the CFA destination when it matches the calling party number. The override applies to both internal and external calls. In cases where the calling party number has been transformed, the calling party number does not match the CFA destination, no override occurs. Before you begin Configure Other Call Forwarding Types, on page 336 Procedure Step 1 From Cisco Unified CM Administration, choose System > Service Parameters. The Service Parameter Configuration window is displayed. Step 2 In the Clusterwide Parameters (Feature - Hold Reversion) area, set the CFA Destination Override service parameter value to True. Call Forwarding Interactions Interaction Feature Calls that are made from the CallBack notification screen will override all the Call Forward configured values on the target DN. The calls should be made before the CallBack recall timer expires, otherwise the calls will not override the Call Forward configured values. Call Back Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs 346 Receiving Calls Enable Destination Override for Call Forwarding