The Queued Output Branch

If the Select Resource step fails to locate an available resource, the script executes the Queued output branch.

Configure the Queued output branch of the Select Resource step to set up a loop that plays a prompt, waits for a certain length of time, and then plays the prompt again, until a resource becomes available.

When the resource does become available, the Select Resource step connects the call, and then continues to the End step, which ends the script.