1. A spoken dialog system that switches contexts within a spoken dialog between a user, the spoken dialog system comprising: a dialog manager with a first-flow controller and a second-flow controller, each of the first-flow controller and the second-flow controller being a finite state model; a module configured, while the spoken dialog is being controlled by the first-flow controller, to receive context-changing input associated with speech from a user that changes the dialog context; a module configured to compare the context-changing input to a table of context shifts; a module configured, if any of the context shifts are activated by the comparison, to pass control to an invoked second flow controller indicated by the context shift; a module configured, if no context shift is activated by the comparison, to maintain control of the spoken dialog with the first controller; and a module configured to store a local context associated with each of the first and second-flow controllers, the local context maintaining a state of the flow controller that is independent of the implemented dialogs, wherein the second-flow controller receives data values stored in the local context of the first-flow controller.
2. The spoken dialog system of claim 1 , further comprising a module configured to maintain a stack of flow controllers wherein each flow controller is added to the stack of flow controllers.