Action node - Queued Callback 
The Queued Callback CallBack, an IVR menu feature for voice, enables the customer to leave his / her number to be called back by an available agent during business hours. action will schedule a callback for a specified skill and add the customer to a skill queue. The difference between this and a standard callback is the priority in the queue, the queued callback session will be placed after all waiting customers.
Note
Queued Callback should be used in the incoming phase.
Additional information
This action will register the contact information of the customer calling the UCC A Unified Contact Center, or UCC, is a queue of interactions (voice, email, IM, etc.) that are handled by Agents. Each UCC has its own settings, IVR menus and Agents. Agents can belong to one or several UCCs and can have multiple skills (competencies). A UCC can be visualized as a contact center “micro service”. Customers can utilize one UCC (e.g. a global helpdesk), a few UCC’s (e.g. for each department or regional office) or hundreds of UCC’s (e.g. for each bed at a hospital). They are interconnected and can all be managed from one central location. (or ask if not recognized) and schedule a callback request for the moment an agent becomes available. It will be placed in the queue of the skill that has been chosen in the node properties. The moment an agent becomes available, the contact number will be called and connected to the Agent (which has the respective skill assigned). This skill queue will serve the waiting customers first and only then connect this request to the next available Agent.
Note
If the customer does not pick up the call this session will be turned into a regular callback. This action requires prior configuration of regular callback.
Read How to Configure Queued Callback to learn how to configure the Waiting Queue item using your SharePoint Dashboard.
Example use in a flow layout (click to enlarge)
Learn more about other available Dialogue Studio Nodes.