Next Generation Wireless Applications: Creating Mobile Applications in a Web 2.0 and Mobile 2.0 World, 2nd Edition

14.8 IMS AS A CONVERGENCE CATALYST

14.8.1 Mobile Roots, Fixed Branches

The first release of IMS specifications in the 3GPP standards body (Release 5) took the view that IMS is a mobile network subsystem. Therefore, various assumptions and implementation decisions were made with the mobile context in mind. For example, the IMS core is assumed to be IPv6 only, in line with the general 3GPP vision. This is problematic for networks where IPv4 is still prevalent, like many existing IP networks. A number of other assumptions were made about the access network being essentially cellular, such as the existence of a smart card (SIM) to facilitate authentication.

For IMS Release 6, the 3GPP included a work item to give IMS greater network flexibility, allowing access from WiFi and last-mile networks (including WiMAX). What we now have is a well-defined IP-based network core that could potentially be used by any telephony service provider to realise an entirely IP-based telephony and connected-services vision. In a short space of time, IMS has grown up and out of its cellular origins. This gives mobile operators an egress into fixed-line environments. The significance of this should be understood within the wider context of IMS potentialities. Not only does IMS allow multimedia services, but it can carry a multitude of other services, such as IM and PTT, which could equally work within a fixed-line environment, abound with cheap PCs, converged devices and ever broadening access (see Figure ...