Samsung patents method for 5G phones to switch networks when service is blocked

1. A method performed by a user equipment (UE) in a wireless communication system, the method comprising: transmitting, to a first access and mobility management function (AMF) entity of a first visited public land mobile network (VPLMN), a first registration request message including information on a network slice for a service; receiving, from the first AMF entity of the first VPLMN, a registration reject message including information on an available network slice, information on an available VPLMN for the available network slice and information on a priority of the available VPLMN, wherein the information on the priority of the available VPLMN includes a priority indicator instructing a VPLMN selection for the UE based on an extent to which the available VPLMN provides the service to the UE; storing the information on the available network slice, the information on the available VPLMN for the available network slice, and the information on the priority of the available VPLMN included in the registration reject message in an operator controlled PLMN list, wherein the operator controlled PLMN list includes pre-configured information stored in the UE; selecting a second VPLMN based on a pre-determined order of a registered PLMN (RPLMN), an equivalent PLMN (EPLMN), user controlled PLMN, the operator controlled PLMN list, and at least one PLMN reported as high quality PLMN; transmitting, to a second AMF entity of the selected second VPLMN, a second registration request message, wherein the second VPLMN is determined based on the information on the available VPLMN for the available network slice and the information on the priority of the available VPLMN included in the registration reject message in case that the operator controlled PLMN list is selected according to the pre-determined order; and receiving, from the second AMF entity of the second VPLMN, a registration accept message as a response to the second registration request message.