The IP multimedia subsystem utilizes the IP?CAN to transport multimedia signalling and bearer traffic. IP?CANs that maintain the service while the terminal moves, hide these moves from the IP multimedia subsystem.
The IP multimedia subsystem is independent of the CS domain although some network elements may be common with the CS domain. This means that it is not necessary to deploy a CS domain in order to support an IP multimedia subsystem based network.
IMS利用IP-CAN传输多媒体信令和承载业务。当终端移动时，IP-CANs会获得服务，但会对IMS隐藏终端的移动。(?)
IMS独立于CS域，尽管一些网络元素会与CS域的共用。这意味网络不需要为支持IMS再部署CS域(?)。