vironment, where the majority of the wireless end hosts are assumed to be handsets. This obviously leaves a large group of ingenious variations of different IPv6 transition tools out of the detailed discussion. 3GPP has advocated dual-stack as the preferred transition mechanism since the begin- ning of the whole IPv6 transition discussion. As we realized and illustrated, dual-stack is not always a commercial or even a realistic technical option during the phased rollout of IPv6. Therefore, considerable effort was also directed to the development of transition mechanisms that are tailored for single IP version access networks. Within the 3GPP mindset the transition mechanisms that rely on tunneling over the cellular link have systematically been played down, which have led to moderate success of address fam- ily translation solutions, NAT64 being a textbook example. In order to alleviate known application level issues of a single IP version in an end host, so-called double translation schemes came into being, which eventually deliver dual-stack to the applications on an end host over single IP version access networks. We also went through a number of known operational concerns, scalability issues, and identified impacts to the 3GPP system architecture. We even touched the surface of IPv6 Transition Mechanisms for 3GPP Networks roaming challenges from the IPv6 point of view. At the end, we specifically laid out and described few rules of thumb on how to get started with a phased IPv6 rollout in a 3GPP network, and pictured the favored transition scenarios. Although the guidance may sound simple and straightforward, the operational reality has proven it to be far from a quick exercise with a timely rollout. References 1. Gilligan, R. and Nordmark, E. Transition Mechanisms for IPv6 Hosts and Routers. RFC 1933, Internet Engineering Task Force, April 1996. 2. Nordmark, E. and Gilligan, R. Basic Transition Mechanisms for IPv6 Hosts and Routers. RFC 4213, Internet Engineering Task Force, October 2005. 3. Carpenter, B. an