stablished con- nection with the network, however it is not actively sending or receiving data. 1. If the UE decides to resume from RRC_INACTIVE (e.g. to send uplink data), it sends the RRCResumeRequest message to the gNB controlling the cell it is camped on, pro- viding the information with which the network can identify its context, i.e. I-RNTI (allocated by the last serving gNB). 2. As the gNB which the UE connects to may not be the one the UE has previously established the connection, the gNB sends the Xn-AP Retrieve UE Context Request message with the UE context ID (e.g. I-RNTI) to the last serving gNB over the Xn interface, in order to obtain the information about the UE context. 3. If the last serving gNB is able to identify the UE context by the ID received in step 2, it replies with the Retrieve UE context Response. This message carries UE security capabilities, PDU sessions information, RRC Context (HandoverPreparationInfor- mation IE), and some other information. 4./5. The gNB and UE complete the resumption of the RRC connection. The UE uses the context information that it has stored and the gNB uses the context information that it has either stored (in the case it is the last serving gNB for that UE) or has received in step 3. 3.3 NG Radio Access Network 6. Optionally (if data forwarding is enabled), the gNB may send the Xn-U Address Indi- cation message to the last serving gNB, which carries data forwarding address infor- mation for all the established PDU sessions and DRBs. 7./8. The gNB performs path switch toward the AMF as in the legacy Xn-based handover. 9. The gNB sends the Xn-AP UE Context Release message over the Xn interface to trigger the release of the UE resources at the last serving gNB. This step is also similar to the legacy Xn-based handover.Xn-A RAN paging message is used, when the last serving gNB received downlink data for the UE. When a UE receives the RAN paging message, the UE initiated state transition procedure described above is performed. 3.3.4.2 Xn User Plane (Xn-U) Interfa