Most of today's IVR dialogues are system-directed, where the system asks questions that users answer. Call routing is a special type of automatic classification system that prompts users with a general phrase. The classification system translates users' utterances to one of several predefined destinations based on a statistical model derived from a corpus of typical user phrases and their corresponding categories. The automated classification system then uses this statistical model to transform user-spoken phrases into categories. Classification systems successfully categorize sentences not in the original training corpus. Users are not limited to uttering sentences covered by a prespecified grammar.