oice and also by the availability of OTT voice services such as Skype at that time). In mobile networks, SMS revenues have been threatened by OTT messaging applications which are typically included with OTT voice services, thus making them attractive to end-users (think of Skype, Viber, WhatsApp, Messenger). Although the revenues from SMS and mobile voice provided by mobile operators decline over time, they are being compensated by increased revenues from mobile data services (that is the IAS provided over mobile access networks) because mobile users still have to pay the cost of Internet access (for instance, a flat fee price or volume-based fee - e.g. per MB or GB). To provide the required QoS the telecom operators (which operate the access and core networks) must invest in capacity by deploying additional bandwidth for the grow- ing Internet traffic. So, traffic growth needs infrastructure investment and also traffic management tools to address congestion issues. To remain sustainable and profitable, 8.4 Network Neutrality Business Aspects telecom operators (which are also ISPs) may change existing business models or intro- duce new ones, including the following: Differentiation of IAS offers with different data caps are a standard approach in fixed and mobile networks (the data caps are many times higher in fixed networks than in mobile networks for the same price). For example, mobile operators can manage traffic growth (and with that capital investments in new equipment in access and core networks) by applying appropriate data caps in their mobile IAS packages to manage traffic growth. The smaller data cap slows traffic growth, and vice versa. Price differentiation and time differentiation can appear in different offerings - for example, free voice calls during the night for packages targeted at younger users, or faster broadband speeds for gamer tariffs (higher speeds also result in lower latency, which is essential for online gaming applications). Possible differentiation is also pro- vision of mobile ser