This study was designed to investigate some important aspects of turn-taking in one type of structured telephone conversation, namely, travel enquiry calls. Specifically, it investigated under what conditions subjects could distinguish turn-final and turn-medial utterances taken from such conversations and presented out of context. The first part of the investigation sought to determine if judges could make this distinction on the basis of an audio presentation of the utterances or on the basis of a typescript of the utterances. We found that judges could distinguish turn-final and turn-medial utterances when presented in audio form, they could not, however, distinguish turn-final and turn-medial utterances on the basis of a typescript alone, except in the case of utterances sampled from just one operator. The second part of the investigation was designed to determine what aspects of verbal content were important in guiding the subjects' judgement of completion on the basis of typescript alone. We looked specifically at the role of topic (for example, utterances concerning ‘time’ or ‘cost’ information) and mode of expression (for example ‘impersonal’ or ‘personal’ mode) in marking turn-final and turn-medial utterances in these calls. We found that it was specific combinations of topic and mode of expression which were most important in allowing subjects to identify turn-final and turn-medial utterances. This interaction was of more significance than either of these two features alone. The general conclusion from this study is that the interaction between meaning and syntax is crucial to the organisation of the turn-taking process, at least in structured telephone conversations.