The present disclosure relates to a communication method and
system for converging a 5th-Generation (5G) communication
system for supporting higher data rates beyond a 4th-Generation (4G)
system with a technology for
Internet of Things (IoT). The present disclosure may be applied to intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building,
smart city,
smart car, connected car, health care,
digital education, smart retail, security and safety services. Disclosed is a method of determining, in a
User Equipment, if a PDU session between the UE and a network, can be transferred between 3GPP and non-3GPP access, when the UE is using a Cellular
Internet of Things, CIoT, optimisation, wherein the determination is performed on the basis of a Control Plane, CP, only indication and if the determination is positive, then the PDU session is not transferred.