10. A system comprising: a processor; means for controlling the processor to obtain task-independent training data; means for controlling the processor to present a prompt to a user; means for controlling the processor to recognize a received user utterance in response to the prompt using an automatic speech recognition engine to yield a recognized user utterance; means for controlling the processor to classify the recognized user utterance using a spoken language understanding module; means for controlling the processor to prompt the user if the recognized user utterance is classifiable by the spoken language understanding module with a confidence more than a predetermined acceptance threshold; and means for controlling the processor to transfer the user to a human if the recognized user utterance is not classifiable by the spoken language understanding module to a predetermined rejection threshold and if a dialog-wide re-prompt counter is exceeded, wherein the received user utterance is transcribed, labeled and used for training the spoken dialog system, and wherein at least one of the acceptance threshold and the predetermined rejection threshold are related to an entity referenced in the recognized user utterance.
10. A system comprising: a processor; means for controlling the processor to obtain task-independent training data; means for controlling the processor to present a prompt to a user; means for controlling the processor to recognize a received user utterance in response to the prompt using an automatic speech recognition engine to yield a recognized user utterance; means for controlling the processor to classify the recognized user utterance using a spoken language understanding module; means for controlling the processor to prompt the user if the recognized user utterance is classifiable by the spoken language understanding module with a confidence more than a predetermined acceptance threshold; and means for controlling the processor to transfer the user to a human if the recognized user utterance is not classifiable by the spoken language understanding module to a predetermined rejection threshold and if a dialog-wide re-prompt counter is exceeded, wherein the received user utterance is transcribed, labeled and used for training the spoken dialog system, and wherein at least one of the acceptance threshold and the predetermined rejection threshold are related to an entity referenced in the recognized user utterance. 13. The system of claim 10 , wherein the system is an automated hidden human.