A terminal device, comprising a transceiver, a memory, and a processor, wherein the memory is configured to store instructions; the transceiver is configured to send, in a first network to which the terminal device is attached, an Internet protocol multimedia subsystem IMS registration request to a first network device, or send, in a second network to which the terminal device is attached, an IMS registration request to a second network device; and the processor is configured to execute the instructions stored in the memory, and when the processor executes the instructions stored in the memory, the terminal device is enabled to: when the Internet protocol multimedia subsystem IMS registration request is sent to the first network device in the first network to which the terminal device is attached, start an IMS timer corresponding to the first network, and deactivate the first network if a registration accept message from the first network device is not received when timing duration of the IMS timer corresponding to the first network reaches first specified duration; and when the Internet protocol multimedia subsystem IMS registration request is sent to the second network device in the second network to which the terminal device is attached, start an IMS timer corresponding to the second network, and deactivate the second network if a registration accept message from the second network device is not received when timing duration of the IMS timer corresponding to the second network reaches second specified duration, characterised in that the first specified duration is different from the second specified duration. the memory is configured to store instructions; the transceiver is configured to send, in a first network to which the terminal device is attached, an Internet protocol multimedia subsystem IMS registration request to a first network device, or send, in a second network to which the terminal device is attached, an IMS registration request to a second network device; and the processor is configured to execute the instructions stored in the memory, and when the processor executes the instructions stored in the memory, the terminal device is enabled to: when the Internet protocol multimedia subsystem IMS registration request is sent to the first network device in the first network to which the terminal device is attached, start an IMS timer corresponding to the first network, and deactivate the first network if a registration accept message from the first network device is not received when timing duration of the IMS timer corresponding to the first network reaches first specified duration; and when the Internet protocol multimedia subsystem IMS registration request is sent to the second network device in the second network to which the terminal device is attached, start an IMS timer corresponding to the second network, and deactivate the second network if a registration accept message from the second network device is not received when timing duration of the IMS timer corresponding to the second network reaches second specified duration, characterised in that the first specified duration is different from the second specified duration. when the Internet protocol multimedia subsystem IMS registration request is sent to the first network device in the first network to which the terminal device is attached, start an IMS timer corresponding to the first network, and deactivate the first network if a registration accept message from the first network device is not received when timing duration of the IMS timer corresponding to the first network reaches first specified duration; and when the Internet protocol multimedia subsystem IMS registration request is sent to the second network device in the second network to which the terminal device is attached, start an IMS timer corresponding to the second network, and deactivate the second network if a registration accept message from the second network device is not received when timing duration of the IMS timer corresponding to the second network reaches second specified duration, characterised in that the first specified duration is different from the second specified duration.