Most recently developed context-aware software applications make unrealistic assumptions about the quality of the available context information,which can lead to inappropriate actions by the application and frustration on the part of the user. In this paper, we explore the problem of imperfect context information and some of its causes, and propose a novel approach for modelling incomplete and inaccurate information. Additionally, we present a discussion of our experiences in developing a context-aware communication application, highlighting design issues that are pertinent when developing applications that rely on imperfect context information.