A communication method, comprising: sending, by a mobility management entity, MME, a bearer setup request message to an evolved NodeB, eNodeB, wherein the bearer setup request message is used to instruct the eNodeB to set up a voice bearer for user equipment; and when the MME receives a bearer setup failure message sent by the eNodeB in response to the bearer setup request message, sending, by the MME, a notification message to the user equipment, wherein the notification message is used to trigger the user equipment to initiate registration or combined registration; and receiving, by the MME, a first registration request message or a first combined registration request message that is sent by the user equipment; sending, by the MME, an indication message to the user equipment, wherein the indication message is used to indicate that a voice over Internet Protocol IP multimedia subsystem, VoIMS, of the user equipment is unavailable, wherein the sending the indication message comprises: sending, by the MME, a first registration acceptance message or a first combined registration acceptance message to the user equipment, wherein the first registration acceptance message or the first combined registration acceptance message comprises first indication information, and the first indication information is used to indicate that the VoIMS of the user equipment is unavailable; wherein that the bearer setup request message is used to instruct the eNodeB to set up a voice bearer for user equipment comprises: the bearer setup request message is used to instruct the eNodeB to set up a bearer whose quality of service class identifier, QCI, is equal to 1 for the user equipment; and wherein the method further comprises: sending, by the MME, a first location update request message to a home subscriber server, HSS, according to the bearer setup failure message, wherein the first location update request message is used to notify the HSS that the VoIMS of the user equipment is unavailable. sending, by a mobility management entity, MME, a bearer setup request message to an evolved NodeB, eNodeB, wherein the bearer setup request message is used to instruct the eNodeB to set up a voice bearer for user equipment; and when the MME receives a bearer setup failure message sent by the eNodeB in response to the bearer setup request message, sending, by the MME, a notification message to the user equipment, wherein the notification message is used to trigger the user equipment to initiate registration or combined registration; and receiving, by the MME, a first registration request message or a first combined registration request message that is sent by the user equipment; sending, by the MME, a first registration acceptance message or a first combined registration acceptance message to the user equipment, wherein the first registration acceptance message or the first combined registration acceptance message comprises first indication information, and the first indication information is used to indicate that the VoIMS of the user equipment is unavailable; wherein that the bearer setup request message is used to instruct the eNodeB to set up a voice bearer for user equipment comprises: the bearer setup request message is used to instruct the eNodeB to set up a bearer whose quality of service class identifier, QCI, is equal to 1 for the user equipment; and wherein the method further comprises: sending, by the MME, a first location update request message to a home subscriber server, HSS, according to the bearer setup failure message, wherein the first location update request message is used to notify the HSS that the VoIMS of the user equipment is unavailable. the bearer setup request message is used to instruct the eNodeB to set up a bearer whose quality of service class identifier, QCI, is equal to 1 for the user equipment; and wherein the method further comprises: sending, by the MME, a first location update request message to a home subscriber server, HSS, according to the bearer setup failure message, wherein the first location update request message is used to notify the HSS that the VoIMS of the user equipment is unavailable.