d, and 3GPP Deploying IPv6 in 3GPP Networks Table 2.2 3GPP releases Release Description of the major 3GPP releases in the context of this book Release-97 The first release of General Packet Radio Service (GPRS) Release-98 Release-99 The first release of the Universal Mobile Telecommunications System (UMTS) Release-4 Release-5 IP Multimedia Subsystem (IMS) [9], and High Speed Downlink Packet Access (HSDPA) [10] introduced Release-6 High Speed Uplink Packet Access (HSUPA) [11] introduced Release-7 HSPA+ introduced Release-8 The first release of LTE Release-9 Dual-Stack PDP Context introduced to 3G Release-10 DHCPv6 Prefix Delegation (DHCPv6-PD) introduced Release-11 Release-12 continued this approach for its first release. However, the second release - Release 2000 - was a bit too difficult to do in just one year, and 3GPP decided to move to releases that are not based on a particular year, and thus not named after a year either. The ETSI releases defining the packet switched architecture, and hence, being of interest for the purposes of this book, were Releases 1997 and 1998. The first 3GPP release was Release-1999. After that the releases were named after the version number of the specifications as Release-4, -5, -6, etc. At the time of writing, 3GPP has just started working on Release-12. One might wonder why 3GPP started from number four instead of some more logical number such as one. However, the 3GPP specification version numbers also indicate the specification maturity, and the numbers from one to three were already taken. We will explain the specification maturity in the next section. Table 2.2 lists the releases until today, and describes the major releases in the context of this book. 3GPP Specifications The 3GPP specifications are usually identified by their numbers. Partly this is because the numbers are rather short, and can be more easily remembered than their sometimes quite obscure titles. Although this is relatively handy for the people who work with the 3GPP specifications every day, it might pro