The present invention relates to a process for generating service function modules for a signalling server which can provide signalling functions for the control of communications via a communications network, particularly of multimedia communications via a packet switching data network, and to a configuration server for generating service function modules for a signalling server which can provide signalling functions for the control of communications via a communications network, particularly of multimedia communications via a packet switching data network, a signalling server or generating service function modules with which the signalling server can provide signalling functions for the control of communications via a communications network, particularly of multimedia communications via a packet switching data network, a computer program for generating service function modules with which a signalling server can provide signalling functions for the control of communications via a communications network, particularly of multimedia communications via a packet switching data network, and a storage medium for generating service function modules with which a signalling server can provide signalling functions for the control of communications via a communications network, particularly of multimedia communications via a packet switching data network.
The invention is based on the provision of telecommunications service functions in a packet switching data network, particularly in the Internet, wherein multimedia communications connections between end subscribers are established via the packet switching data network. In simple cases, pure voice calls or pure video calls are understood by the term “multimedia communications connections”, whereas in more complicated cases the term also means combinations of voice and video as well as possibly additional data, e.g. computer files etc. Pure voice calls via the Internet are also referred to as Voice over Internet Protocol (VoIP) calls.
ITU-T Recommendation H.323, issue 2/98, defines a possible infrastructure for audiovisual and multimedia connections via packet-oriented networks, referred to in the following only as multimedia connections. Such an infrastructure is also required i.a. for Voice over Internet Protocol connections. Alternatives to an infrastructure according to ITU-T Recommendation H.323 are discussed for example within the IETF (Internet Engineering Task Force). The individual components of an infrastructure for establishing audiovisual and multimedia connections are, in the terminology of ITU-T Recommendation H.323: terminals, gateways and gatekeepers, also known as call servers.
Terminals provide access to a packet switching data network and comprise, as a core component, a voice codec with which voice signals are coded into digital data packets and digital data packets are decoded into voice signals. Further codecs, for example video codecs for video signals, can likewise be contained in a terminal.
If a first terminal knows the Internet address of a second terminal, the first terminal can directly establish a multimedia connection to this terminal with the aid of this Internet address. Normally, however, Internet addresses for terminals are not permanently assigned but are re-allocated in each Internet session, so that further components are used to establish a multimedia connection. These are the so-called gatekeepers for establishing and maintaining connections within a packet switching data network, and the so-called gateways for connections to circuit-switched telecommunications networks. The gateways provide an interface function between a packet switching data network and a circuit-switched telecommunications network, for example an ISDN (Integrated Services Digital Network). On the side of the circuit-switched telecommunications network, the gateway communicates for example using the CCITT Signalling System No. 7, while on the side of the packet switching data network it communicates using signalling according to ITU-T Recommendation H.225, which for example describes the establishment and clearance of a connection within a packet switching data network. Additionally, a gateway converts different audio, video and data formats in the respective networks where this is necessary.
Within a packet switching data network, gatekeepers make services for connection establishment and clearance and for connection control available to the connected terminals. As already mentioned, on the one hand terminals can communicate with one another directly without a gatekeeper. On the other hand, terminals advantageously can be supported by a gatekeeper, for example during connection establishment, in which case for example a terminal makes a request to the gatekeeper for a connection to a communications partner terminal. Then the gatekeeper determines the required address of the communications partner terminal and, using the signalling normally employed in the packet switching data network, e.g. signalling according to ITU-T Recommendation H.225 completes the desired connection to the communications partner terminal.
A gatekeeper or gateway can also provide further functions, e.g. service functions similar to the service-switching functions or service-control functions within a so-called Intelligent Network (IN=Intelligent Network, see for example ITU-T Recommendation Q.1215) based on a circuit-switched telecommunications network. A typical example of such service functions of an Intelligent Network is the so-called Call Completion on Busy Subscriber (=CCBS) service. This service can be activated when a called subscriber is busy. If the service is activated by the calling subscriber, a service logic in the called subscriber's exchange sends the calling subscriber's exchange a service signalling message when the called subscriber is no longer busy.
Service functions based on signalling messages can be made available not only in a circuit-switched telecommunications network, but also for a packet switching data network. For this purpose, in a first configuration, service provision devices of a circuit-switched telecommunications network can be addressed from the packet switching data network. However, in a further configuration, such services are provided directly by servers of a packet switching data network, e.g. by gateways or gatekeepers. The creation of the service logics required for this purpose, i.e. the procedures for transmitting and receiving service signalling messages in the respective servers, is however complicated and error-prone, as the procedures must first be coded in a programming language and then be compiled to form machine instructions executable by the servers.
Although, as already stated in the introduction, the present invention is based on problems relating to a packet switching data network, and in particular relating to the Internet, it is not limited thereto. The described problems are however of lesser significance in conventional communications networks as solutions are already available therein in the form of the Intelligent Network. However, due to the different type of signalling, these solutions can only be conditionally applied to packet switching data networks. The solution presented in the following, which was sought specifically for the Internet, can however also be applied to other, conventional communications networks.