e NGN by the ITU-T [1]. Why? Because QoS end-to-end is directly related to signaling, and signaling end-to-end needs to be QoS for Fixed and Mobile Ultra-Broadband, First Edition. Toni Janevski. © 2019 John Wiley & Sons Ltd. Published 2019 by John Wiley & Sons Ltd. 3 QoS in NGN and Future Networks standardized globally to be the same in all telecommunication networks of all telecom operators, fixed or mobile, in each country. For example, end-to-end signaling is needed for services such as voice (to locate the end-user device to deliver a call to it) or television. Although the signaling for voice was created by the IETF as SIP (Session Initiation Protocol), there were other options such as the H.323 standard from the ITU-T for call signaling. However, if every vendor and every operator implements some standardized signaling (or other) protocols and mechanisms, there can be problems with interoperability for signaling between different operator networks, which are autonomous regarding each other. End-to-end signaling in a standardized manner, and also end-to-end QoS provisioning in a standardized manner (which is based largely on signaling as a necessary "tool"), are accomplished with NGN standardization on a global scale. Hence, NGN networks implemented by telecom operators provide the base for interoperability between networks based on standards and offer the possibility of having end-to-end QoS for those services that need it. What have NGNs brought to the telecom world? They have introduced the Internet concept (the winning concept in packet-based networks) of separation of services and underlying networks (including all types of networks and services). That provides the possibility of having different types of access networks, such as fixed access (copper or fiber based) accompanied with Ethernet or WiFi access in the last meters, and mobile access networks (e.g. from 2G to 5G and beyond). NGNs are all-IP networks, something that is realized as a convergence of PSTN/ PLMN toward the Internet as a single netw