This paper reports on conversation analytic research for the Dutch national emergency call-centre. In a corpus study of 120 emergency calls we show that callers' orientations to their communicative tasks are not aligned to the institutional communicative tasks of the call-takers. In a subsequent workplace experiment involving over 2000 calls, it appeared that the use of an alternative question rather than a wh-question, significantly altered callers' emergency deliveries and adapted them to call-takers' communicative needs. The analysis shows two aspects of callers' responses to the different question formats: (i) The alternative questions produced significantly more type-conforming answers than the wh-questions, and also (ii) callers treated their non-conforming answer to alternative question more often as dispreferred than their non-conforming answers to wh-questions. Callers thus treated the preference for type-conformity to be stronger for alternative questions than for wh-questions.