ective test methods quality of service P.800: Methods for subjective determination of transmission quality P.863: Perceptual objective listening quality assessment P.1200-P.1299: Models and tools for quality assessment of streamed media Y-series: Global information Y.1540: Internet protocol data communication infrastructure, Internet protocol aspects, service - IP packet transfer and availability and next generation networks (NGN) performance parameters Y.1541: Network performance objectives for IP-based services Y.1542: Framework for achieving end-to-end IP performance objectives Y.1543: Measurements in IP networks for inter-domain performance assessment Y.1545.1: Framework for monitoring the quality of service of IP network services series, which shows that QoS/QoE topics are considered in all types of telecommunica- tion networks and for all types of telecommunication services. 1.6 General QoS Terminology Terminology standardization in general is necessary for two main reasons: first, to avoid confusion to readers by introducing conflicting terms and definitions; and second, to 1.7 Discussion Real-time Access Transit Access network network network network network Streaming Terminal equipment Internet data End-to-end QoS Note: on both sides of the end-to-end path there can be humans with terminal equipment (PC, smartphone, etc.) or machines (various servers, things, etc.). Figure 1.10 End-to-end QoS. assist alignment between the various groups involved in telecommunication standards development. The terminology for QoS is standardized in ITU-T Rec. E.800 [10]. As discussed in this chapter, the end-to-end QoS depends on the contributions made by all components on the end-to-end communication path, as shown in Figure 1.10. General QoS terminology, which is also used in this book, is given in Table 1.4 [10]. Besides the general QoS terms, there are service-related terms (call setup time, conver- sational quality, cybersecurity, etc.), network-related terms (customer premises equip- ment, network/user interface, in