A user reports that when they are using Cisco Unified Personal Communicator, their status does not change when they are on the phone. What is the typical cause of this issue?

An invalid username or password would prevent the user from authenticating to CUPC entirely, not produce a selective failure where the client works but phone status is not updated.

A locked-out CUP account would block all presence functionality for the user, not specifically cause phone-state synchronization to fail while other features work.

Cisco Unified Presence tracks phone state by subscribing to line-level events in CUCM on behalf of the user; this subscription is only possible if the end user account is explicitly associated with the directory number in CUCM's end user configuration. Without that association, CUP cannot receive on-hook or off-hook notifications for the line, leaving the presence status static regardless of call activity.

If CUP were not enabled for the user, the user would have no presence capability at all rather than a partial failure limited to phone-state reflection.

Cisco Unified Presence enablement is a per-user setting managed in CUCM, not a per-line toggle; no such per-line CUP enable/disable configuration exists to cause this specific symptom.