hich is defined by the International Telecommunication Union (ITU) as packet-based network" that makes use of "multiple broadband, Quality of Service (QoS) enabled transport technologies and in which service related functions are independent from underlying transport-related technologies" [2]. In particular, the IP Multimedia Subsystem (IMS) has been standardized by the Telecommunications and Internet converged Services and Protocols for Advanced Networks (TISPAN) as a core part of a NGN, and forms the main focus of this chapter. During the development of the IMS, two core principles have been established. The first one is the realization that the network architecture needs to be revamped to fully utilize the bandwidth available via new access technologies, allowing multimedia communication sessions over a noncircuit-based network. Secondly, proprietary closed signaling protocols inhibit the growth of new services and stifles innovation. The IMS uses an open, human readable protocol for the control signaling that is deployed widely on the Internet. This lowers the entry barrier for Service Orchestration in the IP Multimedia Subsystem third-party service developers, allowing them to use the experience gained from the Internet in the development of similar services over the network operators' network as well as reducing the need for specialized knowledge about telephony protocols. However, one drawback to the expected influx of developers and services is that research needs to be completed on how to handle interactions (both negative and positive) between these new services. Service conflict detection and resolution is not a new issue. Previous network architectures, such as Intelligent Networks (IN), have suffered from service conflict detection and resolution issues [3]. A summary of techniques used to detect and resolve these conflicts in previous architectures can be found in [4]. The IMS will be no different unless mechanisms are designed and developed to handle these interactions. The situation is expected to