  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. 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.
