 defined in a very flexible way, enabling different multiradio scenarios. The multimedia broadcast multicast service (MBMS) makes it possible to distribute multimedia content efficiently to multiple recipients. Such content could be, for example, video or music clips. Conversational services such as push-to-talk (PoC) are also specified in release 6, together with open mobile alliance (OMA). The main products are the connection processing server (CPS) and the IP multimedia register (IMR). The CPS provides a centralised point of registration, session control and charging for IP multimedia services. The IP multimedia register complements the existing HLR with additional subscriber and service information for SIP subscribers as well as a service deployment mechanism. The IP multimedia core fits easily into the existing network environment and complements existing investments. Core Network Planning and Optimisation Connection Processing Server (CPS) The connection processing server (CPS) is a centralised entity providing control of end-to-end IP multi- media services using the Session Initiation Protocol (SIP). The CPS generates charging data and sends it to the charging gateway. Ready-made incoming and outgoing traffic treatment services are provided for the end-user, e.g. personal lists for session forwarding including redirection to personal contact pages. The CPS also supports the ISC interface towards external SIP based application servers that can offer extended services to subscribers. IP Multimedia Register (IMR) The interface between the 3GPP HSS (HLR server system) and call state control function (CSCF) is known as the Cx interface. The user mobility server (UMS) in the IMR implements the standard Cx interface. The Cx interface is based on the Internet Engineering Task Force (IETF) Diameter Base Protocol and 3GPP Cx application extensions. The diameter layers are run on top of the SCTP (Stream Control Transport Protocol)/IP. The Cx interface supports the transfer of data between the UMS and the CSCF functio