| 摘要 |
The invention proposes a method and an apparatus for reducing break duration in handover of a VoIP conversation from a packet switch domain to a circuit switch domain. The main idea is that a synchronization mechanism is introduced between the session handover procedure at IP multimedia subsystem IMS layer and a cell handover procedure at layer 2, so that enable the two handover procedures to start at or almost at the same time. When a Mobile Switching Centre MSC server receives a request of handover from the source Mobility Management Entity MME, the time required from the time the MSC server transmitting a message to this message arriving at a remote end user equipment UE is computed first, and then is compared with a predetermined time required from the time the MSC server transmitting a message to this message arriving at the local UE. According to the comparison result, determining an order and time for the MSC server transmitting a request of session handover to the Service Centralization and Continuity Application Server (SCC AS) and transmitting a request of cell handover to the source MME, and transmitting above two requests in according to the order and time, to ensure that the time that the request of session handover arrives at the remote end communication terminal is the same or almost same as the time that the request of cell handover arrives at the local communication terminal.
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