arkets, the international transit providers (also referred to as commercial ISPs) are dependent upon the interna- tional market, while the service providers may be dependent upon the national market (e.g. for services provided by telecom operators) or the global market (for OTT services over the public Internet). From the economical point of view the Internet can be considered as a two-sided mar- ket, with the network operators collectively serving as a platform connecting providers of content (e.g. websites) and various OTT services with consumers that use the ser- vices by using the access through the telecom operator, which has a role as a multi-sided platform (as shown in Figure 9.4). Such interpretation also may suggest that quality dif- ferentiation may not be problematic. With view, some may consider that issues simply refer to how costs and profits should be divided between network operators as enabling platform of the two-sided market and the two (or sometimes more) sides of the market. QoS and pricing have been related from the beginning in the telecom world. Tele- phone networks in the twentieth century used differentiated pricing for the same service (telephony, i.e. voice) at different times during the day or different days in the week, in order to discourage callers with lower demand from making calls during peak hours (i.e. the congested period of the day). The idea with such time-of-day pricing was to shift net- work usage to less congested periods by applying lower per-minute charges. The driver for such an approach is different willingness to pay for the service (from the customer side), which provides higher utilization of the network resources (or lower investments in the network to satisfy traffic demand). However, with the convergence of telecommunication networks and service on Inter- net technologies, the approaches have changed to mainly flat fee charges regardless of the volume of voice traffic (on a national basis). Why? Because the access bitrates have increased significantly while the