A communication method for a voice service, comprising: determining, by a session management network element, that a terminal device is to be handed over from a first network to a second network, wherein the session management network element is used for session management in the first network and the second network; and waiting, by the session management network element, until a first moment to send a request message to a mobility management network element in the second network, wherein the request message is used to request to set up a first bearer for a voice service of the terminal device, wherein: the first moment is a moment at which the session management network element receives first notification information from the mobility management network element in the second network, and the first notification information indicates that the terminal device is successfully handed over from the first network to the second network, or the first moment is a moment at which the session management network element receives second notification information from a subscriber data management network element, and the second notification information indicates that the terminal device supports a capability of falling back from the second network to a third network to maintain continuity of the voice service. determining, by a session management network element, that a terminal device is to be handed over from a first network to a second network, wherein the session management network element is used for session management in the first network and the second network; and waiting, by the session management network element, until a first moment to send a request message to a mobility management network element in the second network, wherein the request message is used to request to set up a first bearer for a voice service of the terminal device, wherein: the first moment is a moment at which the session management network element receives first notification information from the mobility management network element in the second network, and the first notification information indicates that the terminal device is successfully handed over from the first network to the second network, or the first moment is a moment at which the session management network element receives second notification information from a subscriber data management network element, and the second notification information indicates that the terminal device supports a capability of falling back from the second network to a third network to maintain continuity of the voice service. the first moment is a moment at which the session management network element receives first notification information from the mobility management network element in the second network, and the first notification information indicates that the terminal device is successfully handed over from the first network to the second network, or the first moment is a moment at which the session management network element receives second notification information from a subscriber data management network element, and the second notification information indicates that the terminal device supports a capability of falling back from the second network to a third network to maintain continuity of the voice service.