This paper describes Vocalist, a robust, portable spoken language dialogue system for telephony applications. It is robust in that it has been demonstrated to perform well with untrained users. It is portable in that its components are designed in a fashion which is application independent. To port to a new application it is necessary only to define new application knowledge bases. The dialogue engine has been equipped with very general knowledge about information-seeking dialogues such that it could, in principle, operate in any application domain with only minimal customisation.