use of SDN. Typically QoS is measured via parameters such as bandwidth, delay, jitter, and loss (the most frequently used ones). QoS is provided to given sets of 3.8 Business and Regulatory Aspects services by giving precedence on QoS-enabled services over other services (e.g. best effort ones). The specification of the QoS targets between the end-users and service providers is traditionally done by SLAs. There are two types of QoS [30]: Hard QoS. This method guarantees the QoS requirements of a given call/session, but may suffer in the case of limited resources. Typical example of hard QoS is constant bitrate bandwidth reservation (e.g. guaranteed bandwidth). Soft QoS. This method is not strict QoS provisioning, i.e. the QoS is not strictly guar- anteed for the entire duration of the connection (i.e. call/session), SO it is more flexible in adaptation to the available resources. A typical example of soft QoS is class-based routing (e.g. the DiffServ approach). What is the relationship between SDN and QoS? Well, SDN improves the QoS with QoS-motivated routing, for example with per-flow routing (instead of class-based aggregate routing) and with simpler mechanisms for that purpose than legacy telecom network infrastructures. Further, SDN may help telecom operators to create more a powerful and more flexible QoS management system framework, with well-defined control mechanisms to adapt to the constantly changing environment in the network regarding the volume of traffic or number of supported end-user services and applica- tions. SDN also allows QoS monitoring on a fine-grained level, such as monitoring per queue, per packet, etc. Finally, SDN is inseparably connected with network virtualiza- tion (many times the terms NFV and SDN are used together), and it can be used for virtualization-based QoS provisioning and QoS policy management. 3.8 Business and Regulatory Aspects The move toward NGNs in the 2010s started the transformation of the legacy telecom- munication sector. The main approach of the NGN is having a s