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Protocol Message Library

This message library organizes telecom protocol messages used across 5G, LTE, IMS, radio access, core network signalling, RAN interfaces, and voice services. Browse message families such as 5G NR RRC, 5G NAS, NGAP, F1AP, E1AP, XnAP, LTE RRC, LTE NAS, S1AP, and IMS SIP to understand message direction, procedure role, key fields, and troubleshooting context.

Use this page as the starting point for finding signalling messages used in registration, authentication, RRC setup, bearer setup, PDU session establishment, handover, paging, UE context management, RAN split interfaces, and IMS call flows.

Main Technology Cards

5G Messages

Protocol messages for NR RRC, 5G NAS, NGAP, F1AP, E1AP, XnAP, and IMS/VoNR signalling.

 LTE Messages

Protocol messages for LTE RRC, LTE NAS, S1AP, X2AP, and EPC-related signalling.

 IMS SIP Messages

SIP requests and responses used in IMS registration, VoLTE, VoNR, call setup, early media, messaging, supplementary services, and call release.

5G Message Families

5G RRC Messages5G NAS MessagesNGAP MessagesF1AP MessagesE1AP MessagesXnAP Messages

LTE Message Families

LTE RRC MessagesLTE NAS MessagesS1AP Messages

IMS SIP Message Families

IMS SIP MessagesSIP RequestsSIP Responses

Browse By Signalling Area

Radio Access Messages

RRC messages used for system information, connection setup, security, reconfiguration, measurements, mobility, release, resume, and reestablishment.

5G RRCLTE RRC

Core Network / NAS Messages

NAS messages used for registration/attach, authentication, security, service request, bearer or PDU session management, and deregistration/detach.

5G NASLTE NAS

RAN-Core Interface Messages

Messages between RAN and core network nodes for UE context, NAS transport, sessions/bearers, paging, mobility, and warning procedures.

NGAPS1AP

Split RAN Interface Messages

Messages used inside split 5G RAN architecture between CU/DU and CU-CP/CU-UP.

F1APE1AP

Inter-RAN Mobility Messages

Messages used between RAN nodes for handover preparation, context transfer, status transfer, and mobility cleanup.

XnAP X2AP

IMS Voice and SIP Messages

Messages used for IMS registration, VoLTE, VoNR, call setup, early media, session modification, supplementary services, and call release.

IMS SIPSIP RequestsSIP Responses

Most Used Message Hubs

5G RRC Messages5G NAS MessagesNGAP MessagesIMS SIP MessagesLTE RRC MessagesF1AP MessagesE1AP MessagesXnAP Messages

FAQ

What is the protocol message library?

It is a structured reference for telecom signalling messages used across 5G, LTE, IMS, radio access, core network, RAN interfaces, and voice services.

Which 5G message protocols are included?

The 5G section includes NR RRC, 5G NAS, NGAP, F1AP, E1AP, XnAP, and IMS SIP signalling.

What is the difference between RRC, NAS, and NGAP?

RRC controls radio signalling between UE and base station. NAS carries UE-to-core signalling. NGAP carries signalling between NG-RAN and AMF over the N2 interface.

What is the difference between F1AP, E1AP, and XnAP?

F1AP runs between gNB-CU and gNB-DU, E1AP runs between gNB-CU-CP and gNB-CU-UP, and XnAP runs between neighbouring NG-RAN nodes.

Where are IMS SIP messages used?

IMS SIP messages are used for IMS registration, VoLTE, VoNR, call setup, early media, session update, messaging, supplementary services, and call release.

Should users start with technology or protocol?

Users who know the protocol can open that protocol hub directly. Users analyzing a call flow can start from the technology hub, such as 5G Messages or LTE Messages.

References