METHOD FOR TRANSITIONING SUPPORT OF COMMUNICATION SESSIONS FOR A USER ELEMENT BETWEEN DIFFERENT TYPES OF SUBSYSTEMS OF DIFFERENT GENERATIONS

摘要

The present invention provides a method for transitioning a local access leg of a communication session for a user element from a serving access network of one generation to a target access network of another generation, where one access network is in a circuit-switched subsystem domain and the other is in a packet subsystem domain. To transition the loca access leg for the user element between the first access network and the second access network, a transitional cell is employed. The local access leg is first transferred to a transitional cell from a serving cell of the serving access network, and is then immediately transferred to a target cell of the target access network, while maintaining continuity of the communication session across both transfers. Maintaining continuity of the communication session means that there is no interruption in the communication session during the transitions.