A method for triggering a Machine Type Communication, MTC, device, comprising: receiving, by a Serving General Packet Radio Service Support Node, SGSN, / Mobility Management Entity, MME, a trigger from an MTC InterWorking Function, MTC-IWF,, wherein the trigger carries at least an International Mobile Subscriber Identifier, IMSI, of an MTC device to be triggered, and information on whether the MTC device is capable of receiving a short message, wherein the MTC device can access a network only in a communication window allocated to the MTC device by the network; determining, by the SGSN/MME, whether the MTC device is in an unattached state; determining whether the MTC device is in the communication window of the MTC device; and when it is determined that the MTC device is in the unattached state, and the MTC device is in the communication window of the MTC device, waiting for attachment of the MTC device to the network; and when the MTC device fails to get attached to the network before expiration of the communication window, sending, by the SGSN/MME, a trigger transmission report to the MTC-IWF, such that after receiving the trigger transmission report, the MTC-IWF saves the trigger by sending the trigger to a Short Message Service Center, SMS-SC, and forwards the trigger transmission report to an MTC server initiating the trigger, wherein the method further comprises: after the SGSN/MME has determined that the MTC device is in the unattached state, determining, by the SGSN/MME, whether the communication window of the MTC device is stored locally; when the communication window of the MTC device is stored locally, determining, by the SGSN/MME, whether the MTC device is in the communication window; when the communication window of the MTC device is not stored locally, further determining, by the SGSN/MME, whether time control information of the MTC device is stored locally; when the communication window of the MTC device is not stored locally, but the time control information of the MTC device is stored locally, generating, by the SGSN/MME, a communication window according to the time control information and a local network strategy, and then determining whether the MTC device is in the generated communication window; when neither the communication window of the MTC device nor the time control information of the MTC device is stored locally, obtaining, by the SGSN/MME, the time control information of the MTC device from a Home Subscriber Server, HSS, / Home Location Register, HLR, generating a communication window according to the time control information and the local network strategy, and then determining whether the MTC device is in the generated communication window. receiving, by a Serving General Packet Radio Service Support Node, SGSN, / Mobility Management Entity, MME, a trigger from an MTC InterWorking Function, MTC-IWF,, wherein the trigger carries at least an International Mobile Subscriber Identifier, IMSI, of an MTC device to be triggered, and information on whether the MTC device is capable of receiving a short message, wherein the MTC device can access a network only in a communication window allocated to the MTC device by the network; determining, by the SGSN/MME, whether the MTC device is in an unattached state; determining whether the MTC device is in the communication window of the MTC device; and when it is determined that the MTC device is in the unattached state, and the MTC device is in the communication window of the MTC device, waiting for attachment of the MTC device to the network; and when the MTC device fails to get attached to the network before expiration of the communication window, sending, by the SGSN/MME, a trigger transmission report to the MTC-IWF, such that after receiving the trigger transmission report, the MTC-IWF saves the trigger by sending the trigger to a Short Message Service Center, SMS-SC, and forwards the trigger transmission report to an MTC server initiating the trigger, wherein the method further comprises: after the SGSN/MME has determined that the MTC device is in the unattached state, determining, by the SGSN/MME, whether the communication window of the MTC device is stored locally; when the communication window of the MTC device is stored locally, determining, by the SGSN/MME, whether the MTC device is in the communication window; when the communication window of the MTC device is not stored locally, further determining, by the SGSN/MME, whether time control information of the MTC device is stored locally; when the communication window of the MTC device is not stored locally, but the time control information of the MTC device is stored locally, generating, by the SGSN/MME, a communication window according to the time control information and a local network strategy, and then determining whether the MTC device is in the generated communication window; when neither the communication window of the MTC device nor the time control information of the MTC device is stored locally, obtaining, by the SGSN/MME, the time control information of the MTC device from a Home Subscriber Server, HSS, / Home Location Register, HLR, generating a communication window according to the time control information and the local network strategy, and then determining whether the MTC device is in the generated communication window.