Improvements in and relating to CIOT optimisations in a telecommunication network

Disclosed is a method of operating a UE in NB-N1 mode wherein the UE informs a serving network about a number of Data Radio Bearers, DRBs, that the UE is able to support, according to its capabilities. The method involves controlling the establishment of User Plane resources for the UE; if a Payload container type IE is set to "NI SM information", the Request type IE is set to "initial request"; an AMF in the network verifies how many DRBs are already present for the UE and if the AMF determines that there are User Plane resources that are equal to a maximum number of DRBs that the UE supports, then the AMF either: (a) sends a message back to the AMF; or (b) establishes the session as a control plane only session. The method relates to improvements in Cellular Internet of Things (CIoT) optimisation.