SpeechPA is an ontology-based speech interface for personal assistants in specialized domains. In SpeechPA, we use a set of task and domain ontologies for handling knowledge efficiently, separating domain and task models for reasoning. In addition, the ontologies are also used for improving the interaction between ther users and her personal assistants constituting the user's interface. In this paper, we present such an interface and apply it to a multiagent system supporting users accessing government services. From the user's point view, the system is a Service Centre and the personal assistant is its Service Provider. As a clear result of this conversational speech interface, we expect an increase in the quality of assistance and a reduction of the time needed to answer a user's request.