irements are driven by the nature of the access domains and the associated policy management of each. For example, the requirements for QoS are very different in wireline versus wireless networks. During the course of adaptations' development for the different access types, the challenge is to ensure that those do not diverge from the goal. Otherwise, we will end up with a separate IMS architecture per access type. To address this cross-access technology issue, industry needs to define and agree on a truly IMS core architecture for multimedia services across all network types. 9.10.2 Policy Matters In the past, different sets of policies were hard wired into each dedicated network. A voice network, for example, has policies to handle voice traffic only. In the next generation in networks where we have multiple types of traffic flows, voice dedicated policies simply would not work. Keeping this challenge in mind, IMS has defined a Policy Decision Function (PDF) that provides the linkage between the application and the underlying transport network. PDF is also responsible for governing the admission of applications traffic and monitoring network resources for that traffic type. Although PDF is efficient, the industry still needs to thoroughly understand the policy related require- ments on the IMS and underlying infrastructures. And then develop solutions that can address the policy related challenges. IMS, Services and Applications 9.10.3 IMS Test and Measurement IMS networks must be tested end-to-end: from the access to the core including the various protocols and interfaces. The challenge is to find the right suite of test cases since the number of protocols and interoperability issues is quite large in the open VoIP and IMS environment. No single vendor or operator has the bandwidth to conduct comprehensive interoperability, roaming, capacity, protocols, interfaces, devices, or other tests to ensure end to end viability of IMS networks. To address this challenge, the MultiService Forum (MSF) organized GMI 2008 