As a first step to achieve Fixed Mobile Convergence or FMC (Finnie, 2004), many equipment manufacturers now produce dual-mode mobile phones (SIP/WiFi & GSM). Motorola, Nokia and others have been offering such devices that connect to the Internet via a WiFi network whenever possible, or via a gateway of the traditional mobile network when the phone is beyond the range of WiFi networks. BT Fusion, a service rolled out by British Telecom based on Unlicensed Mobile Access (UMA) is an example of FMC on the service provider side. UMA, a 3GPP global standard, developed by major mobile and fixed/mobile operators and their primary vendors to create a cellular/Wi-Fi convergence solution to support all existing mobile voice and data services, can integrate into existing mobile networks, support all Wireless Local Area Network (WLAN) environments, and can easily fit in the future network evolution plans, including IP Multimedia Subsystem (IMS).
IMS based on the protocols and principles of Internet Protocol (IP) telephony, is an evolving architecture for providing voice, video and other multimedia services to mobile and fixed phones. Compared to other IP-based protocols, IMS emphasizes central management and billing functions, thus allowing operators to offer centrally administered VoIP and other multimedia services on a managed IP network. This is a critical feature to the operators as they are accustomed to provide services to their customers in a “captive” environment. IMS standards come from the 3rd Generation Partnership Project (3GPP), a consortium focused on evolving GSM networks to 3G W-CDMA, and the detail specifications can be found at http://www.3gpp.org/specs/specs.htm.
Today mobile operators have a head start in the FMC race. Their VoIP service can run over any fixed broadband network and their mobile voice users rely on the mobile operators’ existing infrastructure or their captive managed network. This advantage will disappear in time as fixed and mobile broadband Internet access (WiFi, WiMAX and 3.5G/4G) becomes widely available from multiple competing providers. Since 3rd party VoIP services, like Vonage or Skype, can run over anyone’s broadband connection, mobile operators lose their lock on mobile voice services through market competition. Neither Skype nor Vonage uses or needs IMS. For now, however, mobile operators can launch FMC services more readily and attract more customers.