not support IPv6 - at least not to the same level as IPv4. Deploying IPv6 in 3GPP Networks At the beginning of 2000s, the introduction of 3rd Generation (3G) network services and mobile phones was seen as a major driver for IPv6 adoption. However, for a long time 3G phones were used mostly for voice calls, and only secondarily for Internet access. The introduction of mobile broadband services, and of smartphones, changed the course of events, and exactly what was expected happened - just about ten years later. Until recently basically only Nokia Symbian based smartphones supported IPv6. However, now IPv6 is slowly becoming a standard feature in mobile phones due to the requirements of the major mobile network operators. 1.8.2 IPv6 Network Deployments The fist global IPv6 network was the IPv6 technology testbed 6bone (6bone) [41]. The 6bone was created by the IETF IPv6 community to provide a place where the IPv6 technology could be tested, connecting different IPv6 test projects, and for gathering IPv6 operational experience. The network itself was mostly a virtual network deployed over the global Internet infrastructure. It had its own network prefix 3FFE: : /16 [42] that was temporarily assigned to the testbed. The testbed was operational from 1996 to 2006 when it was decommissioned on 6 June 2006 (note the date: 6.6.6) marking both the end of the 6bone and the first IPv6 day. Sometimes erroneously, 6bone has been said to be the Internet IPv6 network backbone. However, the intention was always for 6bone to be a temporary testbed in the test phase of the technology. As IPv6 technology matured, and the Internet itself became increasingly IPv6 capable, 6bone was no longer needed. The 6bone prefixes are not routed over the Internet anymore. The definition of the Internet core is a difficult one. Due to the distributed nature of the Internet, it is difficult to state which operators provide the true core of the Internet. Often, so-called Internet Tier 1 operators are considered to be the core of the Internet. But thi