Numerous approaches have tackled the issue of obtaining requirements through natural language (NL) statements. However most of them are considering this issue as a translation problem from NL statements to formal specifications. They do not recognise the elicitation process as a dialogue between users and computer. As a result most of the burden of writing correct requirements still lies with users; the computer doing only a translation.In this talk, I will contrast these approaches with an approach where both users and computer take part in a dialogue to define the requirements. One of the problems of having a dialogue is the need to agree on what to speak about, to allow users to change topic while providing guidance. This problem is tackled by using focus rules. After a brief presentation of the notion of focus, I will show how a dialogue manager based on it can be integrated with an elicitation system. I will detail how the responsibilities are shared between the elicitation system and the dialogue manager. The advantages of using a dialogue manager, such as mixed-initiative, will then be discussed. Finally an example of dialogue produced by an early implementation of the system will be given.