Which option would an administrator use to find all unassigned directory numbers in Cisco Unified Communications Manager?

The Route Plan Report in Cisco Unified Communications Manager lists all route plan components - including directory numbers, route patterns, and translation patterns - along with their partition and assignment status. An administrator can filter or review this report to identify directory numbers that have not been assigned to any device or user. No other built-in CUCM tool provides this consolidated view of unassigned DNs.

CDR (Call Detail Records) logs call activity and does not report on the configuration or assignment status of directory numbers.

CAR (CDR Analysis and Reporting) is a reporting tool for call records and usage statistics, not for reviewing directory number assignments.

The Cisco Reporting Tool focuses on system and device reports such as phone inventory, not specifically on unassigned directory numbers.

There is no native 'Directory Number Lookup' feature in CUCM designed to surface unassigned numbers.