IH Function in the Protocol Stack of a Multi-Radio Mobile Device gathered through technology-specific Layer 2 service access points for each of the enabled technologies, such as 802.11, 802.16 and 3GPP/3GPP2 for cellular phone networks. MIH in Practice The first devices and service that are putting MIH into practice are targeting the personal telephony sector, enabling cellular phone subscribers to use a single device to access cellular services when on the move and VoIP services when at home. BT's Fusion service, launched in the UK in 2005, uses Bluetooth enabled Motorola handsets together with a Bluetooth hub as a gateway for VoIP calls connected via a BT ADSL broadband Internet connection. Launched in partnership with Vodaphone, this service allows calls to be handed off between the cellular network and the VoIP over Bluetooth connection when the handset comes within range of the Bluetooth hub. Motorola announced a family of products in early 2006 that enable handoff between cellular phone and 802.11 based VoIP services. The residential seamless mobility gateway (RSG - Figure 14-2) includes an 802.11b/g access point, a four-port router and a VoIP adapter, allowing seamless handoff of voice calls between the home WLAN and the cellular network when using a dual-mode handset. These devices provide the expected VoIP features, such as 802.11i security and voice traffic prioritisation on the WLAN to ensure QoS, Chapter Fourteen Figure 14-2: Motorola Residential Seamless Mobility Gateway (Courtesy of Motorola Corporation) as well as offering many digital phone features, such as supporting multiple lines, caller ID, call waiting and call forwarding services. Ahead of the full development and ratification of the 802.21 standard, these devices rely on proprietary software and protocols to achieve a limited degree of media independent handoff and, in the BT case, the handoff only works with specific service providers. Nevertheless, these early demonstrations of the concept provide a foretaste of the remarkable flexibilit