mber of fixed-line phone subscriptions in favor of mobile subscriptions. Big carriers like AT&T and all the European incumbents have both the fixed and the mobile access network, and it is natural to conceive a new telephone solution where the difference disappears. Several such proposals have been done, where the customer has only one, personal phone that is similar to a cellular terminal. When the terminal is in the range of the customer house network, that can be either a dedicated radio link with the telephone base or a broadband Wi-Fi network, the telephone behaves like a fixed-line phone; when the telephone is far from the house, it behaves like a cellular phone [24,25]. This simple service profile can be implemented in several different ways, either leverag- ing on network intelligence or leaving all the management to the terminal software. In any case, the seamless transition from one working mode to another is a key perfor- mance, since during a phone call the working mode change has to have a minimal impact on the call quality. Beyond the simple telephone call, there are other services that are similar on fixed and mobile terminals, for example, a video call or the delivery in real time of images of a sport event. Starting from these similitudes, several studies have foreseen that in the future network not only telephones but all video services will pass seamlessly from fixed to mobile termi- nals [26]. For example, in such a network, it would be possible to start a video call using the call-enabled set-top box and the TV screen. After a certain time, it should be possible to pass the call on a mobile terminal without interrupting it. As far as the mobile terminal remains within the reach of the home Wi-Fi, it works like a fixed terminal (with the corresponding lower cost), and when the caller goes out of the Wi-Fi's reach, the termi- nal connects to the mobile network and changes tariff accordingly. All these changes must happen without a significant drop of the call quality (but for the passage from t