3GPP Message Database

AMF -> NG-RAN 3GPP TS 38.413

5G NGAP - Downlink NAS Transport

Downlink NAS Transport is the NGAP message the AMF uses to carry a downlink NAS message toward the UE through the NG-RAN over the N2 interface.

RRC 5G

5G NR - RRC Setup

Downlink NR RRC message sent by the gNB to establish SRB1 and move the UE into the connected RRC procedure.

gNB -> UE 3GPP TS 38.331

NG-RAN -> AMF 3GPP TS 38.413

5G NGAP - Uplink NAS Transport

Uplink NAS Transport is the NGAP message the NG-RAN uses to carry a subsequent uplink NAS message from the UE toward the AMF over the N2 interface after the initial access is already established.

NG-RAN -> AMF 3GPP TS 38.413

5G NR - Initial UE Message

NGAP initiating message used by the NG-RAN to transfer the UE's first uplink NAS message to the AMF.

AMF -> NG-RAN 3GPP TS 38.413

5G NGAP - Initial Context Setup Request

Initial Context Setup Request is the NGAP message the AMF sends to NG-RAN to establish UE context, security, and initial PDU session resources after successful NAS entry and core-side authentication steps.

NAS LTE

LTE Attach Request

Attach Request is the EPS NAS message the UE uses to start the LTE attach procedure and ask the network to create EPS mobility-management context.

UE -> MME 3GPP TS 24.301

NG-RAN -> AMF 3GPP TS 38.413

5G NGAP - NAS Non Delivery Indication

NAS Non Delivery Indication is the NGAP message the NG-RAN sends to the AMF when a downlink NAS message cannot be delivered to the UE.

LTE RRC LTE

LTE RRC Connection Setup

Downlink LTE RRC message sent by the eNodeB to establish SRB1 and move the UE into connected-mode signaling.

eNodeB -> UE 3GPP TS 36.331

LTE RRC LTE

LTE RRC SIB1 - System Information Block Type 1

Broadcast LTE RRC message on BCCH and DL-SCH that gives the UE the essential access identity, cell selection, scheduling, and change-detection context needed before it can use the wider SIB set.

eNodeB -> UE 3GPP TS 36.331

Recently Added Messages

Source NG-RAN node -> Target NG-RAN node 3GPP TS 38.423

5G XnAP - SN Status Transfer

SN Status Transfer is the XnAP message the source NG-RAN node sends to the target NG-RAN node to transfer PDCP sequence-number and HFN status, and related mobility information, so the target can continue bearer handling without duplicate or out-of-order treatment errors.

Target NG-RAN node -> Source NG-RAN node; also M-NG-RAN node -> S-NG-RAN node in DC branches 3GPP TS 38.423

5G XnAP - UE Context Release

UE Context Release is the XnAP message used to indicate that radio and control-plane resources for the associated UE context may be released at the other node after handover success, dual-connectivity release, or UE context retrieval completion.

Initiating NG-RAN node -> Peer NG-RAN node; outcomes: peer -> initiator 3GPP TS 38.423

5G XnAP - Xn Setup Request

Xn Setup Request is the first XnAP interface-management message an NG-RAN node sends after the Xn-C transport association becomes operational so the peer node can learn the initiating node identity, served-cell inventory, and grouping information before normal inter-node signaling starts.

Peer NG-RAN node -> Initiating NG-RAN node successfulOutcome 3GPP TS 38.423

5G XnAP - Xn Setup Response

Xn Setup Response is the successful XnAP outcome the receiving NG-RAN node returns after accepting Xn Setup Request, making the Xn relationship operational and optionally returning the peer-side served-cell and grouping view the initiator should store for later inter-node procedures.

gNB-CU-UP -> gNB-CU-CP initiatingMessage 3GPP TS 37.483

5G E1AP - Bearer Context Release Request

Bearer Context Release Request is the E1AP message the gNB-CU-UP sends to the gNB-CU-CP when the CU-UP needs the control plane to handle release of an existing bearer context.

gNB-CU-UP -> gNB-CU-CP unsuccessfulOutcome 3GPP TS 37.483

5G E1AP - Bearer Context Setup Failure

Bearer Context Setup Failure is the E1AP unsuccessful outcome the gNB-CU-UP returns when it cannot accept the requested bearer-context creation for a UE.

gNB-CU-CP -> gNB-CU-UP initiatingMessage 3GPP TS 37.483

5G E1AP - Bearer Context Setup Request

Bearer Context Setup Request is the E1AP message the gNB-CU-CP sends to the gNB-CU-UP to create the user-plane bearer context, including PDU session, DRB, QoS, and NG-U transport instructions for one UE.

gNB-CU-UP -> gNB-CU-CP successfulOutcome 3GPP TS 37.483

5G E1AP - Bearer Context Setup Response

Bearer Context Setup Response is the E1AP successful outcome the gNB-CU-UP returns after accepting bearer creation, confirming the CU-UP side UE identity and reporting the resulting bearer and user-plane state.

Source NG-RAN node -> Target NG-RAN node 3GPP TS 38.423

5G XnAP - Handover Request

Handover Request is the XnAP message the source NG-RAN node sends to the target NG-RAN node to request preparation of resources for an incoming handover on the Xn interface.