h as Telstra and Optus in Australia. Such service provision created a new revenue stream for players in the retail layer of the broadband ecosystem. Another direction which emerged in the mid-2000s is commonly known as over-the-top (OTT) services. OTT companies use the telecommunications infrastructure network to provide services such as telephony, video telephony, messaging and SO on. Prominent examples include Skype, FaceTime and WhatsApp. These companies substitute the services of a retail layer telecommunications service provider, and are therefore competitors to these companies. The business system diagram associated with OTT services is relatively simple and is shown in Figure 14.4. Subscriber Capacity retail Service OTT service Retailer operator provider Device Capacity wholesale wholesale Device Core network manufacturer operator Figure 14.4 Business system diagram for an OTT service business Content Delivery and Net Neutrality Case Study 14.1: Mobile Messaging and Voice Applications The popularity of smart phones and the introduction of broadband data plans in third generation (3G) and fourth generation (4G) mobile subscriptions, made it possible for a number of third party applications to provide telephony and short-messaging services. These apps competed with 'monopoly' mobile telecommunications services which accounted for most of operators' revenues. Early apps were evolved from personal computer (PC) voice over IP (VoIP) applications such as Skype and Viber which allowed for primarily low-rate international, and mobile-to-fixed line calls, as well as instant messaging. Furthermore, communication between apps was free. Additional services such as video telephony, multi-party conference, file sharing and gaming were provided over the platforms associated with these apps. The apps were however less successful in substituting mobile-to-mobile telephony and messaging as the call rates were not signif- icantly lower than those charged by mobile operators. Furthermore, Skype and Viber worked mainly with us