Circuit switching user agent system, communication device, and service providing method used therefor

摘要

A circuit switching user agent system include a service processing device arranged in a home network of an IMS (IP Multimedia Subsystem)/MMD (Multi-Media Domain). The circuit switching user agent system also includes a communication device arranged in a visited network where a mobile terminal has visited, the communication device having a function of interconversion between a UNI (User-Network interface) signal in a circuit switching network to which the mobile terminal is connected and a signal used in the IMS/MMD,