 know the characteristics and present conditions of their network to request the exact quality that it should be able to access. Users see the network as an information transport system which should be adapted if they want to use it. In case of continuous media services (CM), and in the special case of stream- ing services, SIP needs to be extended with media server control mechanisms. In this way, there are works in progress in IETF and W3C that propose an architectural framework of media servers control. On the other hand, there are other proposals focused on exploiting the cooperation between SIP and RTSP. The latter, the applications servers, are components in charge of external applications execution, which adds intelligence to the services. Examples of advanced services in a VoIP environment are call filtering, destination block- age, call forwarding, etc. The number of services deployed in this environment has no limit and service providers have been forced to offer a high level of per- sonalized services according to the necessities of a user or group of users. Fur- thermore, service providers look for a service delivery platform environment that minimizes the time-to-market before the incorporation of new services. Advanced mechanisms to implement such services can be provided by the Java community and the open source software community. In the following, approaches of media server control and application servers are explained in more detail. 2.2.1 Media Server Control Mechanisms A media server is a media processing network element that performs all the media processing for advanced services. It is controlled by the application server, which provides a service execution environment, application-specific logic, and all the signaling for one or more services. Application servers and media servers work together in a client-server or master-slave relationship. The application servers provide the service logic for each specific application and the media server acts as a media processing resource for the appli