Network handover method, device, and system

User equipment (UE), comprising:

• a transceiver;
• at least one processor;
• and
• a non-transitory computer-readable storage medium coupled to the at least one processor and storing programming instructions for execution by the processor, the programming instructions instruct the at least one processor to:
• send, through the transceiver, a request message to a mobility management entity (MME) for requesting circuit switched fallback (CSFB);
• receive, through the transceiver, a handover command sent by an evolved base station (eNodeB) for instructing the UE to hand over from a long term evolution (LTE) network to a circuit switching (CS) domain of a second generation (2G) or third generation (3G) network for the CSFB, and the handover command comprises information about a CS domain wireless resource that is allocated by the 2G or 3G network to the UE for handing over from the LTE network to the CS domain of the 2G or 3G network;
• hand over from the LTE network to the CS domain of the 2G or 3G network according to the handover command received by the receiving unit;
• send, through the transceiver, in the CS domain of the 2G or 3G network, a first CS call connection setup request message to a mobile switching center (MSC) for requesting the MSC to generate a first session, or send, in the CS domain of the 2G or 3G network, a call confirmation message to the MSC, responding to a second CS call connection setup request message, wherein the second CS call connection setup request message is used for requesting the UE to generate a second session;
• and
• receive, through the transceiver, a session release message sent by the MSC, wherein the session release message is used for instructing the UE to release a third session that is generated by the UE in a process of handing over from the LTE network to the CS domain of the 2G or 3G network.

A non-transitory computer readable medium comprising computer program codes stored thereon, executable by one or more digital processors for providing system configurations, the computer program codes including:

• instructions for sending a request message to a mobility management entity (MME) for requesting circuit switched fallback (CSFB);
• instructions for receiving a handover command sent by an evolved base station (eNodeB) for instructing the UE to hand over from a long term evolution (LTE) network to a circuit switching (CS) domain of a second generation (2G) or third generation (3G) network for the CSFB, and the handover command comprises information about a CS domain wireless resource that is allocated by the 2G or 3G network to the UE for handing over from the LTE network to the CS domain of the 2G or 3G network;
• instructions for handing over from the LTE network to the CS domain of the 2G or the 3G network according to the handover command;
• instructions for sending in the CS domain of the 2G or 3G network, a first CS call connection setup request message to a mobile switching center (MSC) for requesting the MSC to generate a first session, or send, in the CS domain of the 2G or 3G network, a call confirmation message to the MSC, responding to a second CS call connection setup request message for requesting the UE to generate a second session;
• and
• instructions for receiving a session release message sent by the MSC for instructing the UE to release a third session that is generated by the UE in a process of handing over from the LTE network to the CS domain of the 2G or 3G network.