This paper proposes a Model-View-Controller architecture for Spoken Dialogue Management (SDM) that consists of VoiceXML as View, i.e., as presentation layer and a Controller layer using a Model to determine the next possible system utterance. In this paper we focus on the Model layer and present a Dialogue Domain Ontology, which combines the Information State and the ontology theory. The Dialogue ontology can be extended by several optional components such as a domain reasoner, which supports and governs the ontology, an analysis layer to classify the user or a translation layer, which triggers various applications. Our work aims at a unified model for SDM related information handling for various tasks in intelligent environments.