IMS includes several modules, such as call session control, Home Subscriber Server (HSS), Media Gateway Control Function (MGCF), Media Gateway (MGW), Multimedia Resource Function Controller (MRFC) and so on.

• IMS包括呼叫会话控制、归属用户服务器(HSS)、媒体网关控制(MGCF)、媒体网关(MGW)以及媒体资源控制(MRFC)等功能模块。