 become increas- ingly complicated as services will no longer be provided solely by the network oper- ator but also by their partners and third party developers. This area has not been standardized yet, unlike the main core of the IMS framework. A study concluded by the Third Generation Partnership Project (3GPP) in September 2008 high- lighted this area as requiring further critical research [5]. This chapter presents the current state of service orchestration in the IMS as well as future developments in the area. First, the existing IMS facilities for service orchestration are introduced and limitations discussed. Second, the requirements for an improved service orches- tration system are presented. This is followed by a discussion on the current state of research in the area. The existing research focuses mainly on determining where to locate a conflict detection and resolution mechanism, as well as how these conflicts can actually be resolved. The chapter is concluded with some recommendations for future work. 8.2 IP Multimedia Subsystem Traditionally, network operators had to develop single point solutions for each ser- vice that they offered the end user. This led to a duplication of effort, with vastly complicated Operations and Business Support Systems (OSS/BSS). Multiple inter- faces had to be developed, often proprietary, between the services and the existing charging and support systems. The IMS aims to reduce this duplicated effort (and thus, reduce the CAPEX and OPEX of the operator) by running each service over a single platform. It has been designed to allow the rapid prototyping of new, inno- vative services that can be enriched through the addition of any kind of multi- media. This is enabled through the use of a packet-based network and common functions such as user authentication and charging which can be reused by any service. The result is a single IP-based network and the operator no longer has to maintain several different platforms and networks, greatly reducing the cost of maintenance. Th