We propose that emphasis as a prosodic marker can be used for disambiguating Greek spatial and temporal expressions in a task-oriented dialog system, contributing to the production of clear, definite and specific instructions and to a naturally-sounding spoken output produced by the system's Conversational Agent. Our claim is supported by the use of extra-linguistic markers as pointers to the core of the semantic content of sentences in spoken Greek sublanguages (Alexandris & Fotinea, 2004b), as well as data from two sets of transcribed spoken corpora from the domains of Engineering and Broadcast News.