Despite the extensive work on human-computer interaction regarding methods of involving users and designing for high degrees of usability, there is surprisingly little published on how procurer organizations understand, reason about, and require usability. This study focuses on how one taxi company dealt with usability requirements when procuring a new dispatch system. We have conducted ten interviews with various stakeholders in the company and analyzed related documentation in order to discover the process. The case shows how the concept of usability matured during over time. The taxi company dealt with requirement elicitation by developing prototypes in small reference groups. They did no formal analysis of the operators' cooperation with each other at the operator central, but they did include experienced users, which created implicit scenarios. The supplier company did not focus on the efficiency of the operators or, for that matter, the cooperative demands of the operator central in their original design, which became evident when the procurer organization requested a redesign that emphasized user tasks. This indicates, on one hand, the extent to which procurers must understand usability and cooperation to procure good systems design and, on the other hand, the extent to which designers must understand business and activity processes in order to design good systems.