ontinue a session they initiated on a mobile device on their desktop PC. However, in order to develop this solution, it is necessary to consider that the delivery and adaptation of multimedia contents in distributed and heteroge- neous environments requires flexible control and management mechanisms in terminals and in control entities inside the network. On one hand, there is MPEG-21 Digital Item Adaptation (DIA), which provides normative descrip- tions for supporting adaptation of multimedia content, but does not define interactions with transport and control mechanisms. On the other hand, there is SIP, which is an application-layer protocol used for establishing and tear- ing down multimedia sessions. It uses Session Description Protocol (SDP) which is a format for describing streaming media initialization parameters. Recently, an evolution of SDP, SDPng [19], was proposed in order to address the perceived shortcomings of SDP. Both technologies come from different worlds, and in order to develop a solution for advanced signaling, it is important to reach interoperability between the IETF approaches on multimedia session establishment and con- trol, and the MPEG-21 efforts for multimedia streaming and adaptation to bring advanced multimedia service provisioning and adaptation services to the customer. Some proposals that join MPEG-21 and SDPng exist [20], [21], but they are at draft level and their focus is general, without detailing imple- mentation aspects in solutions such as session mobility. The main idea is to contribute to the XML model in which MPEG-21 and SDPng are based. There are proposals where MPEG-21 is used to provide a common support for implementing and managing end-to-end QoS [22]. As Figure 2.10 shows, MPEG-21 is proposed as a Cross-Layer Adaptation. 2.5 Service Convergence Platform of Telecom Operators Nowadays, there are different initiatives for the integration of telecommunica- tions networks. They share the common objective of defining platforms that allow the development of new and comp