A CALL HANDOFF CONTROL METHOD, USER DEVICE, VOICE CALL CONTINUITY SERVER AND COMMUNICATION SYSTEM FOR PRODIVING VOICE CALL CONTINUITY

摘要

A call handoff control method and communication system thereof and a user device are provided, used for avoiding effecting the normal call while a handoff is performed in the case of non-calling state, e.g. ringing/ring back tone/keeping etc. The said method includes: the user device initiates a request for handing off; determine whether the call is ongoing, if it is, the handoff is permitted, if it is not, the transnormal process is performed. The said system includes: a user device and a voice call continuity server; the said user device is used for sending a handoff request to the voice call continuity server; the said voice call continuity server, after receiving the said handoff request, determines whether the call is ongoing, if it is, the handoff is permitted, if it is not, the transnormal process is performed. A user device also is provided accordingly. This invention can prevent the user device from handing off in the case of non-calling state, e.g. ringing/ring back tone/keeping etc.