In the following years the Internet will undergo a radical change with respect to its utilisation. According to the forecasts the traffic of the TV broadcasting will approximately be of the same magnitude as the traffic of the legacy utilisations (WWW, E-mail and data transfer, with P2P added to these). The Internet will become something like a new TV broadcasting medium. Although the traffic of VoIP will be much smaller in volume with respect to the aforementioned ones, almost a dwarf contribution, but it will be very important, as ? according to the experiences up to now ? customers are willing to pay for the interpersonal communications a price higher even with some orders of magnitudes. The prognoses will de detailed in the presentation.

The classical model of the Internet is built on the direct end-to-end accessibility, on the best efforts connectionless data transfer and on an accounting based on the capacity of the connections. Although the end-to-end accessibility is now considerably hindered by the extensive use of NAT, but hopefully it will be broadly restored with the spread of IPv6. The projects aimed to the rethinking the Internet (GENI, Stanford Cleanslate, etc.) also remain essentially within these frameworks. The classical model of the telecommunications enterprises (Telcos) is the connection oriented date transfer with ? possibly even at an elevated level ? guaranteed quality of service (QoS), and with an accounting based on the amount of data transferred (which was reduced to a time based accounting in case of the legacy phone system). This method, however, is well adapted to the more stringent requirements of the VoIP and video transfers.

It is difficult to harmonise the legacy Internet and Telecom models and as the Telecoms are thoroughly squeezed by the decreasing revenues, due partly to the spread of VoIP, too, it is understandable that they try to elaborate a new network architecture differing from the classical Internet. This new architecture would make possible a better control of the network and the quality of service (QoS) as well as it should provide a better, more detailed accounting. This initiative is the IP Multimedia System (IMS), launched by the mobile service providers, but it is intended to a much broader application area. The presentation will review the main features of IMS.