1. Why multimedia IP?

The IP multimedia domain can be considered as a network enabling the provision of IP multimedia services to a user who accesses it from an underlying network. This network offers the user IP connectivity, initially UMTS with release 5, then I-WLAN in release 6 and ADSL in release 7.

Before the IMS architecture was built, the supporting network (e.g. GPRS) enabled access to services running on service platforms directly connected to this network. Services supported in this way use the client/server mode, and do not allow simple interaction between services.

IMS, on the other hand, makes it possible to offer interpersonal services by combining voice and data services. It also makes it possible to combine several services to make one service more sophisticated (for example, by combining the presence service with a call forwarding service)....