Where are external voice DNs sourced from in a CCE Dial Plan?

External voice DNs are sourced from CUCM in a CCE Dial Plan. External voice DNs are the DNs that are not associated with any CCE device, such as agent phones, VRU peripherals, or gateways. They are used to route calls to destinations outside the CCE network, such as PSTN numbers, voicemail, or other PBXs. CUCM is responsible for provisioning and managing these DNs and assigning them to the appropriate devices or trunks. CVP can also use external voice DNs to send calls to CUCM for further routing or treatment.

References:

Troubleshooting Cisco Contact Center Enterprise (CCET) course, Module 3: Troubleshooting Call Flow Issues, Lesson 3.1: Troubleshooting CCE Call Flows, Topic: CCE Dial Plan1

Configuration Guide for Cisco Unified Customer Voice Portal, Release 12.6 (1) - System Configuration [Cisco Unified Customer Voice Portal] - Cisco, Chapter: Dialed Number Pattern Configuration2