Method for requesting an unregistered UE to perform registration in the IMS

摘要

The invention provides a system for requesting an unregistered User Equipment, UE to perform an Internet Multimedia Sub-system, IMS session in an IMS, the system comprising:
- a calling UE for initiating a Circuit Switching, CS domain call to a called UE to request the called UE to conduct an IMS registration using a control message;
- the called UE for receiving the control message and informing the calling UE that whether the called UE has been registered in the IMS or not, or whether the called UE prefers to perform the IMS registration or not; and
- a network entity for processing the IMS registration of the called UE between an IMS core entity in the IMS and the called UE which receives the IMS registration request from the calling UE.