A method for service optimization, applied to a first communications device, characterized in that the first communications device is a terminal having a plurality of subscriptions, and the method comprises: after an emergency service initiated in a first network is ended, performing a waiting-related operation before performing a first operation, wherein the waiting-related operation is any one of the following: an operation of waiting for a first time period; an operation, before the first time period is overrun, when a first condition is satisfied, of stopping waiting for the first time period; and an operation of waiting for an incoming call, wherein the first time period is a time period starting from a time point at which the emergency service is ended; wherein the first operation comprises at least one of the following: sending leaving-related information or a message related to requesting leaving to the network element of the first network; wherein the leaving-related information comprises at least one of the following: a request for leaving, a request for a release, a request for suspension; and returning to a second network; wherein the first network is a communications network corresponding to a first subscription of the first communications device, the second network is a communications network corresponding to a second subscription of the first communications device. after an emergency service initiated in a first network is ended, performing a waiting-related operation before performing a first operation, wherein the waiting-related operation is any one of the following: an operation of waiting for a first time period; an operation, before the first time period is overrun, when a first condition is satisfied, of stopping waiting for the first time period; and an operation of waiting for an incoming call, wherein the first time period is a time period starting from a time point at which the emergency service is ended; wherein the first operation comprises at least one of the following: sending leaving-related information or a message related to requesting leaving to the network element of the first network; wherein the leaving-related information comprises at least one of the following: a request for leaving, a request for a release, a request for suspension; and returning to a second network; wherein the first network is a communications network corresponding to a first subscription of the first communications device, the second network is a communications network corresponding to a second subscription of the first communications device. an operation of waiting for a first time period; an operation, before the first time period is overrun, when a first condition is satisfied, of stopping waiting for the first time period; and an operation of waiting for an incoming call, wherein the first time period is a time period starting from a time point at which the emergency service is ended; wherein the first operation comprises at least one of the following: sending leaving-related information or a message related to requesting leaving to the network element of the first network; wherein the leaving-related information comprises at least one of the following: a request for leaving, a request for a release, a request for suspension; and returning to a second network; wherein the first network is a communications network corresponding to a first subscription of the first communications device, the second network is a communications network corresponding to a second subscription of the first communications device. sending leaving-related information or a message related to requesting leaving to the network element of the first network; wherein the leaving-related information comprises at least one of the following: a request for leaving, a request for a release, a request for suspension; and returning to a second network; wherein the first network is a communications network corresponding to a first subscription of the first communications device, the second network is a communications network corresponding to a second subscription of the first communications device.