A method for transmitting a non-access stratum, NAS, signaling request message the method performed by a wireless device and comprising: transferring, by an NAS layer of the wireless device, the NAS signaling request message to an access stratum, AS, layer to transmit the NAS signaling request message to a base station, wherein the NAS signaling request message includes an indication indicating at least one preferred or required optimization method among an optimization method of optimizing an evolved packet system, EPS, using a control plane, CP, and an optimization method of optimizing the EPS using a user plane, UP, for a cellular Internet of things, CIoT; transmitting, by the AS layer of the wireless device to the base station, a radio resource control, RRC, connection resume request message including the preferred optimization solution and the NAS signaling request, wherein the base station selects a network node supporting the EPS using CP and the EPS using UP for the CIoT, wherein the base station transmits an S1-AP-based initial UE message to the selected network node, wherein the S1-Ap-based initial UE message includes the preferred optimization solution and the NAS signaling request, wherein the selected network node transfers an initial context setup request message including an NAS signaling accept message, and wherein the base station transmits an RRC connection resume complete message to the AS layer of the wireless device, and receiving, by the NAS layer of the wireless device, from the AS layer, an NAS signaling accept message or an NAS signaling reject message from the network node, wherein when the at least one preferred or required optimization method is not supported by the network node, the NAS signaling accept message or the NAS signaling reject message further includes a cause field, wherein, when the NAS signaling reject message is received, the cause field indicates that the optimization method required by the wireless device is not supported by a network, and after the NAS signaling reject message is received, reattempting, by the NAS layer, to transfer the NAS signaling request message to the AS layer until a predetermined maximum number of re-attempt has reached, performing, by the NAS layer, to select a public land mobile network, PLMN, that support the optimization method required by the wireless device. transferring, by an NAS layer of the wireless device, the NAS signaling request message to an access stratum, AS, layer to transmit the NAS signaling request message to a base station, wherein the NAS signaling request message includes an indication indicating at least one preferred or required optimization method among an optimization method of optimizing an evolved packet system, EPS, using a control plane, CP, and an optimization method of optimizing the EPS using a user plane, UP, for a cellular Internet of things, CIoT; transmitting, by the AS layer of the wireless device to the base station, a radio resource control, RRC, connection resume request message including the preferred optimization solution and the NAS signaling request, wherein the base station selects a network node supporting the EPS using CP and the EPS using UP for the CIoT, wherein the base station transmits an S1-AP-based initial UE message to the selected network node, wherein the S1-Ap-based initial UE message includes the preferred optimization solution and the NAS signaling request, wherein the selected network node transfers an initial context setup request message including an NAS signaling accept message, and wherein the base station transmits an RRC connection resume complete message to the AS layer of the wireless device, and receiving, by the NAS layer of the wireless device, from the AS layer, an NAS signaling accept message or an NAS signaling reject message from the network node, wherein when the at least one preferred or required optimization method is not supported by the network node, the NAS signaling accept message or the NAS signaling reject message further includes a cause field, wherein, when the NAS signaling reject message is received, the cause field indicates that the optimization method required by the wireless device is not supported by a network, and after the NAS signaling reject message is received, reattempting, by the NAS layer, to transfer the NAS signaling request message to the AS layer until a predetermined maximum number of re-attempt has reached, performing, by the NAS layer, to select a public land mobile network, PLMN, that support the optimization method required by the wireless device.