Voice over IP in the WiFi Network business models: Will voice be a killer application for WiFi Public Networks?

The stunning growth of WiFi networks, together with the spreading of mobile telephony and the increasing use of Voice over IP (VoIP) on top of Internet, pose relevant questions on the application of WiFi networks to support VoIP services that could be used as a complement and/or competition to the 2G/3G cellular networks. Voice has been, is, and will surely be one of most important killer applications for many of the telecommunications networks. Till now, WiFi networks are centred on Internet access services, not covering a significant market for voice services. However, the succeeding VoIP services working on top of Internet as the ones provided by Skype or Vonage, and the irruption on the terminal market of intelligent dual WiFi/Cellular phones can enable different new scenarios for VoIP over WiFi. In these scenarios, private residential and corporate WiFi connections, WiFi hotspots and wide-area networks may act as complementary infrastructure support for supplying itinerant voice services combined with instant-messaging and multimedia services at advantageous prices, and enabling new competing business models in the voice market. The paper explores the state of the art on the capability of WiFi networks to support voice services in a user itinerant context, identifying actual and future strengths, weakness, opportunities and threats. First of all, the paper reviews the key aspects on the changing structure of the voice market, dominated by a clear evolution to mobility, itinerancy and increased use of VoIP-based services. The evolution of business models, coverage for WiFi networks (hotspots, municipal networks, cooperative networks and) and user voice service use patterns are also analysed in order to asses the potentialities for complementing or-in some scenarios-substitute the cellular networks. In order to identify the critical success factors for the application of WiFi networks to carry voice communications, a multidisciplinary approach is taken, considering different aspects implied in the success of WiFi voice services. The main aspects analyzed consist on: technical issues on access technology (QoS concerns in existing WiFi networks and future evolution), terminal equipment technology and market, roaming and seamless integration of access technologies, and regulation of VoIP services. Next, the market structure is analysed, together with the cooperation/competition dynamics among different actors as cellular operators, wireless ISPs, VoIP service providers, or terminals and software providers. Several possible evolution scenarios are presented, ranging from cellular and integral operators controlling the vertical market, where WiFi hotspots are used as a complement to 3G/2G networks, …