data to control the services, but would have interfaces between the SCSCF and the other AS. The call for this functional element was made after gaining experience from the difficulties arising in service interaction management from previous net- work architectures [4]. This entity was then moved to become part of a SIP AS, where it remained dormant for several years. It eventually fell under the manage- ment of the 3GPP Work Group SA2 (Architecture), and renamed the SCIM. The 3GPP started a study in June 2006 to investigate this function and by September 2008 it had determined that many enhancements were needed. 8.3.1 Combined Service Examples In order to speed up the development of new services, the Open Mobile Alliance (OMA) develops a set of "enablers" or service capabilities. For example, the OMA provides a Presence enabler that can be used to add presence to any existing applica- tion [10]. These enablers (including email notification, instant messaging, etc.) have been designed in a modular fashion to allow the easy creation of rich combinational services. It is predicted that in the future the SCIM will control these interactions. A few examples of these combinational services are provided below to show the flexibility and potential of these service interactions. They are not meant to be deployed real-world services, but rather example concepts to provide the reader with a reference framework for the following sections. Service Orchestration in the IP Multimedia Subsystem 8.3.1.1 Presence-Based Simultaneous Ring An IMS user can register several different identities and several different devices with the IMS network at the same time. Through the use of SIP forking, it is pos- sible to ring these different devices at the same time when trying to establish a call with the given user. Through the use of a presence capability, it is possible to enhance this service by only ringing the device that indicates the user's presence as available and not away. Thus, not all his devices start ringing at the same time. I