A number of phantom communication sessions and a number of contact center agents are assigned to a high priority contact center queue. The number of phantom communication sessions are greater than or equal to the number of assigned contact center agents. The high priority contact center queue is used for coordinating communication session routing with an external control application. A first contact center agent of the number of contact center agents is determined to be available. The first contact center agent is assigned to a first phantom communication session in response to determining that the first contact center agent is available. This results in a notification being sent to the external control application that the first contact center agent is available. This allows the external control application to coordinate routing of the communication session.