In this paper we describe the evaluation of a version of a train time table information system that combines explicit verification with mixed-initiative dialogue control in the first part of the interaction. In the second part of the interaction callers were given more freedom in negotiation and navigation. The evaluation is based on the responses of 68 subjects who called the service from their homes and completed a questionnaire; plus ten subjects who performed the same tasks in the laboratory. All subjects carried out three scenarios, of increasing complexity. It appeared that the explicit verification does not add more turn to the dialogue compared to implicit verification. Subjects found it difficult to deal with the open questions in the second part of an interaction, that were meant to facilitate navigation.