2. TISPAN Release 2

2.1 Motivations for introducing IMS and TISPAN

Before going on to describe TISPAN, we'd like to shed some light on the motivation behind the development of the IMS and TISPAN architecture.

The origins of IMS can be traced back to the 3GPP group, whose primary aim was to develop and maintain technical specifications for 3G mobile networks. The IMS first appeared in 3GPP release 5 in 2002, and has since been developed in subsequent versions. The main idea behind IMS is to provide a single architectural framework for the distribution of services in all-IP networks, whatever the nature of the access network. IMS is therefore first and foremost a technology that will support telecoms services, but not an implementation of these services per se. IMS must enable the...