The History of the IMS Standardization
In Chapter 1 we mentioned that the IMS (IP Multimedia Subsystem) uses Internet protocols. When the IMS needs a protocol to perform a particular task (e.g., to establish a multimedia session), the standardization bodies standardizing the IMS take the Internet protocol intended for that task and specify its use in the IMS. Still, no matter how simple this may sound, the process of choosing protocols to be used in the IMS can sometimes get tricky. Sometimes, the Internet protocol that is chosen lacks some essential functionality, or does not even exist at all. When this happens the IMS standardization bodies contact the standardization body developing Internet protocols to work together on a solution. We will cover this collaboration in Section 2.5. Nevertheless, before jumping into that we will introduce in Section 2.1 all the standardization bodies involved in IMS development. We need to know who is who and which functions of the IMS each of them performs.
2.1 Relations between IMS-related Standardization Bodies
The ITU (International Telecommunication Union) IMT-2000 (International Mobile Telecommunications-2000) is the global standard for 3G networks. IMT-2000 is the result of the collaboration between different standards bodies. It aims to provide access to telecommunication services using radio links, which include satellite and terrestrial networks.
We will focus on two of the standard bodies involved in IMT-2000: 3GPP (Third ...