An IP Phone doesn't log in to Extension mobility, what should you ensure is running to fix this?

The Cisco Extension Mobility feature is delivered through the IP Phone Services framework, which requires the Application Engine (Cisco Tomcat and associated phone service processes) to be active on the CUCM node. Without it running, the phone cannot reach the Extension Mobility login URL and the feature fails silently. Verifying the service is activated and started in Cisco Unified Serviceability is the first troubleshooting step.

There is no CUCM service named 'Extension Services'; this is a distractor that conflates the feature name with a real service dependency.

Mobility Services refers to the Cisco Mobility Services Engine used for wireless location tracking and context-aware services, which is unrelated to Extension Mobility login.

CDP (Cisco Discovery Protocol) is used for neighbor discovery and VLAN voice configuration on switch ports, not for authenticating Extension Mobility user logins.