Abstract.  Today mobile network operators offer a wide variety of mobile Internet services to their customers including mobile email, banking, and news services. The acceptance of these services is heavily based on quality of service (QoS) experienced by the user. So far the discussion of QoS has been very network centric and the key to user satisfaction has been the network performance. In this paper we analyze the relationship between QoS perceived by the customer and network performance offered by the service provider. We conduct a lab experiment where network performance variables were controlled. Statistical analysis of the results indicates that there is no 1:1 correspondence or even truly linear relationship between network performance and perceived QoS as recommended by the International Telecommunications Union-Telecommunication (ITU-T). Instead the relationship varied from application to application. We examine several usability factors as potential reasons behind this phenomenon and make suggestions for future research.