IP [37]. Another main component is a SIP Servlets container. The next layer is composed by the CallControl, which is responsible for the main control of the calls and the redirection to the respective service. The implementation follows the Front Controller and the Jain Java Call Control C 2009 by Taylor & Francis Group, LLC SIP Handbook: Services, Technologies, and Security Specification [13]. The second part is a group of components designed to facil- itate the design and implementation of value-added services. They provide a level of abstraction for the service implementation. Over this middleware, the services are executed. A states machine-oriented deployment is proposed in order to diminish the development of the services. 2.7.3 Example of SIP Cross-Layering: Lightpath Establishment As explained in the cross-layering section, the session information contained in SDP can be used by the application server to request, for example, a lightpath establishment between the end points. This idea was deployed in Provisioning and Monitoring of Optical Services (PROMISE) [33], a European co-operation project under the CELTIC-EUREKA cluster, focused on supporting a range of advanced high capacity services over an adaptable optical network infrastruc- ture, which GMPLS protocols make possible. The main results of the project were a control plane-enabled testbed to showcase the provisioning and main- tenance of optical services in a real-world context. One of these services was the provision of an optical path between a HD transmission unit and a HD receiving unit, using the SIP-CMI approach. In order to establish this path, the SIP Application Server (SMPC) had to request, using Web services, the optical service before successfully establishing the SIP session (Figure 2.16), and initiating the HD transmission. 2.7.4 Examples of High-End Videoconferencing In recent years, video conferencing systems have been an important area of telecommunications research, resulting in a large number of products that can be used to trans