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 (., 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. . | Chapter 2 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 . 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 . Nevertheless before jumping into that we will introduce in Section 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. Relations between IMS-related Standardization Bodies The ITU International Telecommunication Union IMT-2000 International Mobile Tele-communications-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 Generation Partnership Project and 3GPP2 Third Generation Partnership Project 2 . However they are not the only ones working within IMT-2000. Other bodies such as the ITU-R ITU-Radiocommunication Sector for instance are also involved in IMT-2000 but in different areas from the IMS. Both 3GPP and 3GPP2 have standardized their own IMS. The 3GPP IMS and the 3GPP2 IMS are fairly similar but nevertheless have a few differences mostly related to the difference in the cellular aspects of 3GPP and 3GPP2 cellular .
