This paper presents the differences between operating systems (OS) of terminal devices and their characteristics in generating data traffic. An important factor in generating data traffic is also the OS of terminal device because each OS does not generate equal amount of data traffic. The aim of this paper is to show how much data traffic generate terminal devices that use different OSs. By accessing different networks, the same device also detects differences in generating data traffic. Obtained data from the study also shows the differences and characteristics of each OS. Data traffic measurements were performed by viewing the same video track using the YouTube application on all terminal devices and using NetWorx, SurPlusMeter, My Data Manager and Daily Data Sense applications. Access to the data network was achieved using Wi-Fi, UMTS and LTE networks. Based on obtained data by this study, a comparison of data traffic was made for each OS.