Technical reference hub for telecom engineers
Structured protocol references, message databases, call flows, troubleshooting guides, releases, and engineering tools for wireless and telecom engineers.
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Troubleshooting Guides
5G Initial Access Troubleshooting
Isolate failures in cell search, PBCH decode, SIB1 acquisition, suitability checks, camping, and pre-random-access gating.
TAI and Tracking Area Mismatch Troubleshooting
Troubleshoot TAC broadcast errors, tracking-area restrictions, roaming-area mismatch, and area-related registration reject causes.
AMF Selection and GUAMI Issues
Troubleshoot wrong AMF targeting, stale GUAMI or 5G-GUTI context, and broken AMF-selection hints across RRC and NGAP.
5G Registration Failure Troubleshooting
End-to-end guide for registration reject, incomplete registration, AMF selection issues, and first-access failures.
Initial Context Setup Failure Analysis
Diagnose failures during Initial Context Setup and isolate core, policy, or radio-side blockers.
PDU Session Establishment Failure
Diagnose failed session setup, 5GSM reject causes, policy gaps, and missing path creation.
Latest Updates
Path Switch Request is the target-NG-RAN-to-AMF message used after successful handover so the 5GC can switch the NG-U downlink termination point to the new target-side termination point.
5G NGAP - Path Switch Request FailurePath Switch Request Failure is the AMF-to-NG-RAN message used on the unsuccessful branch of the Path Switch Request procedure when the 5GC cannot switch the NG-U downlink termination point for all requested PDU session resources.
5G NGAP - Handover FailureHandover Failure is the target-NG-RAN-to-AMF message used on the unsuccessful branch of Handover Resource Allocation to indicate that target-side resource preparation failed and the handover cannot continue on the success path.
5G NGAP - Handover NotifyHandover Notify is the target-NG-RAN-to-AMF message used in the Handover Notification procedure to confirm that the UE has arrived at the target cell and that handover execution completed successfully.
5G NGAP - Handover Preparation FailureHandover Preparation Failure is the AMF-to-source-NG-RAN unsuccessful-outcome message used to indicate that target-side handover preparation failed and the handover cannot proceed.
5G NGAP - Handover SuccessHandover Success is the AMF-to-source-NG-RAN message used during DAPS handover to inform the source side that the UE has successfully accessed the target NG-RAN node.