1. A method for managing individual call sessions of an interactive voice response (IVR) system comprising: providing a plurality of event data messages in an event stream to a complex events processor (CEP) by an interactive voice response (IVR) system, wherein each event data message comprises at least a Stream_ID and an individual textual element from a series of textual elements, wherein the Stream_ID is a unique identifier that identifies a call session between a calling entity and the IVR system, and wherein the series of textual elements represents a unit of speech input provided by the calling entity converted to textual elements by the IVR system; creating a text string from the textual elements of event data messages having identical Stream_IDs by the CEP, wherein the Stream_ID of the event data messages is associated with the created text string, and wherein said text string is a textual representation of the speech input provided by the calling entity; processing the text string by the CEP, wherein the CEP utilizes a plurality of user-defined business rules; when analysis of the text string requires an issuance of an action message by the CEP, appending the Stream_ID associated with the text string to the action message; conveying the action message to the IVR system; and modifying the call session associated with the Stream_ID of the action message by the IVR system in accordance with the action message, wherein other call sessions being handled by the IVR system are unaffected by said modification.