Embodiments of the present invention disclose a method for a handover from a circuit switched domain to a packet switched domain, a device, and a communications system. One of CS to PS handover methods includes receiving, by a target mobility management entity, a CS to PS handover request message that corresponds to a first UE and is from an MSC; triggering setup of a dedicated VoIP bearer that corresponds to the first UE and is between an SGW and an MGW; sending a handover request message to a target access network to instruct the target access network to prepare a handover resource for the first UE; and sending a CS to PS handover response message corresponding to the first UE to the MSC.