Which feature allows users to know if colleagues are available before making a call in 3CX?

The feature that allows users to know if colleagues are available before making a call in 3CX is Presence. Presence functionality provides real-time information about the availability of coworkers, indicating whether they are online, busy, away, or offline. This feature is integrated into the 3CX system, allowing users to see their colleagues' status at a glance. By leveraging this information, users can make informed decisions about when to make calls, which ultimately enhances communication efficiency within the organization.

The other options, such as Call flow, Voicemail, and Auto-attendant, serve different purposes within the 3CX system. Call flow pertains to how calls are routed through the system, Voicemail allows users to leave messages when someone is unavailable, and Auto-attendant provides automated responses to incoming calls, directing them to the appropriate department or person without the need for human intervention. While all these features contribute to overall communication management, they do not specifically provide the visibility into colleagues' availability that the Presence feature does.