Provided in one embodiment of the present specification is a method for user equipment (UE) for an Internet protocol multimedia subsystem (IMS) voice session. The method can comprise the steps of: establishing an EMS voice session by using a non 3GPP interworking function (N3IWF) or an enhanced packet data gateway (ePDG) through non-3rd generation partnership project (3GPP) access; determining that voice is not supported on a current NG-RAN on the basis of that the UE must moves the IMS voice session to a 3GPP access; and handing over a protocol data unit (PDU) session for the IMS voice session of the non-3GPP access to an evolved packet core (EPC) of the 3GPP access on the basis of the determination.