Terminal switching method and device and acquisition method and device for source access gateway address

The utility model provides a switching method of mobile terminal, comprising the following steps: step one, after the terminal is switched from a source access gateway to a target access gateway, the terminal sends a first message carrying the IP address before the switch of the terminal to the target access gateway; step two, to respond the first message, the target access gateway searches the corresponding network mobile agency according to the IP address; step three, the target access gateway sends to the network mobile agency the mobile IP binding message to bind the IP address of the terminal and the IP address of the target access gateway. The utility model also provides a device for mobile terminal switching, and a method and a device for acquiring the address of the source access gateway. With the technical proposal, the utility model has the advantages of saving air interface resource and ensuring the continuity of conversation.