The invention relates to intelligent network services provided by a packet-switched network and, more particularly, to services provided by a wireless packet-switched network.
Mobile communications systems have been developed in order to free people from fixed telephone terminals without hindering their reachability. Along with the mobile communications systems, a variety of services provided through mobile stations have also developed. Various new forms of services are currently being planned for what are known as the third generation mobile communications systems, such as the Universal Mobile Telecommunications System (UMTS) and IMT-2000 (International Mobile Telecommunications 2000). A majority of these services is designed to use packet-switched transmission. Packet-switched services are also being developed for the current mobile communications systems, such as the Pan-European mobile communications system GSM (Global System for Mobile Communications), one of the objects of the GSM Phase 2+ standardization at ETSI (European Telecommunications Standard Institute) being the General Packet Radio Service GPRS. The GPRS allows packet data transmission between mobile data terminals and external data networks, with the GSM network functioning as an access network.
The mobile communications systems under development are expected to fulfil the need for a wide range of future services. It is difficult now even to imagine many of the services required in the future. The services will become more and more complex, and they will comprise an increasing number of independent functions. It would be reasonable to implement at least some of the services as intelligent network services. A problem is, however, that prior art intelligent network solutions are based on circuit-switched data transmission and they cannot as such be applied to a packet-switched service.
The use of the intelligent network is based on call control. A call is modelled by originating and terminating basic call state models O_BCSM and T_BSCM in a switching centre. The packet-switched network cannot utilize this model, since it does not know the concept ‘call’. In the packet-switched network, data is transferred in a session, during which packet flow can be transferred to or from the terminal. Further, during the same session the terminal can transmit and/or receive packets to and from several other parties. A difference between an originating and a terminating party is not made in the session, only the packet flow, regardless of its direction, is handled. During the session, it is also possible that nothing is transferred anywhere. In intelligent network basic call state models, such cases are not described.