Which feature allows users to manage their own voicemail through a web interface?

The feature that allows users to manage their own voicemail through a web interface is the Voicemail Pro web portal. This platform provides a dedicated interface specifically designed for users to interact with their voicemail settings and messages conveniently from any web browser. Users can listen to messages, change greetings, and adjust various settings, making it a highly accessible tool for voicemail management.

The other options, while they may offer different functionalities, do not focus on voicemail management through a web interface in the same way. The Call Manager interface typically allows users to manage call setups and configurations, while the User Control Panel is more focused on broader user account management features. The Voicemail Settings App might provide some voicemail-related functionalities but does not serve as a web interface for managing voicemail like the Voicemail Pro web portal does.