A User Equipment, UE, comprising: a transmission and reception unit configured to receive, from a control device, a Protocol Data Unit, PDU, session establishment reject message in a PDU session establishment procedure; and a controller configured to start a back-off timer with a back-off timer value, in a case that first information and the back-off timer value are included in the PDU session establishment reject message, and in a case that a Single Network Slice Selection Assistance information, S-NSSAI, was provided by the UE during the PDU session establishment procedure, wherein the first information is a cause value indicating insufficient resources for specific slice, the back-off timer is a timer for S-NSSAI based congestion control, the back-off timer is associated with the S-NSSAI that the UE provided during the PDU session establishment procedure, and in a case that second information indicating whether the back-off timer is applied in a registered Public Land Mobile Network, PLMN, or all PLMNs and the first information are included in the PDU session establishment reject message, when the second information indicates that the back-off timer is applied in the registered PLMN, another PDU session establishment request message for the S-NSSAI is not sent in the registered PLMN while the back-off timer is running, and when the second information indicates that the back-off timer is applied in the all PLMNs, another PDU session establishment request message for the S-NSSAI is not sent in the all PLMNs while the back-off timer is running. a transmission and reception unit configured to receive, from a control device, a Protocol Data Unit, PDU, session establishment reject message in a PDU session establishment procedure; and a controller configured to start a back-off timer with a back-off timer value, in a case that first information and the back-off timer value are included in the PDU session establishment reject message, and in a case that a Single Network Slice Selection Assistance information, S-NSSAI, was provided by the UE during the PDU session establishment procedure, wherein the first information is a cause value indicating insufficient resources for specific slice, the back-off timer is a timer for S-NSSAI based congestion control, the back-off timer is associated with the S-NSSAI that the UE provided during the PDU session establishment procedure, and in a case that second information indicating whether the back-off timer is applied in a registered Public Land Mobile Network, PLMN, or all PLMNs and the first information are included in the PDU session establishment reject message, when the second information indicates that the back-off timer is applied in the registered PLMN, another PDU session establishment request message for the S-NSSAI is not sent in the registered PLMN while the back-off timer is running, and when the second information indicates that the back-off timer is applied in the all PLMNs, another PDU session establishment request message for the S-NSSAI is not sent in the all PLMNs while the back-off timer is running. when the second information indicates that the back-off timer is applied in the registered PLMN, another PDU session establishment request message for the S-NSSAI is not sent in the registered PLMN while the back-off timer is running, and when the second information indicates that the back-off timer is applied in the all PLMNs, another PDU session establishment request message for the S-NSSAI is not sent in the all PLMNs while the back-off timer is running.