5G F1AP System Information Delivery Confirm Message

Message Fact Sheet

Protocol	f1ap	Network	5g
Spec	3GPP TS 38.473	Spec Section	System Information Delivery procedure
Direction	Not a standalone F1AP PDU in TS 38.473 Release 18	Message Type	Clarification page for SI delivery confirmation handling

Full message name	System Information Delivery Confirm
Protocol	F1AP
Technology	5G
Direction	Not a standalone F1AP PDU in TS 38.473 Release 18
Interface	F1-C
Signaling bearer / channel	No standalone System Information Delivery Confirm signalling bearer / Not applicable as a separate F1AP message
Typical trigger	A trace review, decoder label, implementation note, or troubleshooting workflow expects a System Information Delivery Confirm after System Information Delivery Command.
Main purpose	Clarifies that TS 38.473 defines System Information Delivery Command for requested SI broadcast, but not a separate System Information Delivery Confirm PDU. Engineers should validate SI handling through Transaction ID correlation on the command, DU broadcast behavior, UE SI acquisition, Error Indication, or later gNB-DU Configuration Update handling.
Main specification	3GPP TS 38.473, System Information Delivery procedure
Release added	Not defined as a standalone TS 38.473 message
Procedures where used	SI delivery troubleshooting, Trace validation after System Information Delivery Command, SIB broadcast verification, DU broadcast scheduling checks, UE SI acquisition validation, Decoder label cleanup

What is System Information Delivery Confirm in simple terms?

System Information Delivery Confirm is not defined as a standalone F1AP message in TS 38.473 Release 18; SI delivery is driven by System Information Delivery Command and verified through DU broadcast behavior, UE SI acquisition, and related follow-up signalling.

Clarifies that TS 38.473 defines System Information Delivery Command for requested SI broadcast, but not a separate System Information Delivery Confirm PDU. Engineers should validate SI handling through Transaction ID correlation on the command, DU broadcast behavior, UE SI acquisition, Error Indication, or later gNB-DU Configuration Update handling.

Why this message matters

There is no standard F1AP System Information Delivery Confirm in TS 38.473 Release 18. Validate SI delivery from the command fields and the radio/RRC evidence.

Where this message appears in the call flow

System Information Delivery

Call flow position: After System Information Delivery Command, TS 38.473 does not define a separate successfulOutcome confirm message.

Typical state: The DU should broadcast the requested SI or report problems through other applicable procedures.

Preconditions:

The CU has sent System Information Delivery Command.
The DU has a valid target NR CGI and SIType List from the command.
Trace analysis is checking whether requested SI became available over radio.

Next likely message: No System Information Delivery Confirm; verify DU broadcast, UE SI acquisition, Error Indication, or gNB-DU Configuration Update when applicable

Validation without a confirm PDU

5G F1AP diagram showing that System Information Delivery Confirm is not a standalone TS 38.473 message — Decode branch: do not wait for a successfulOutcome confirm that is not defined by the Release 18 ASN.1.

Call flow position: SI delivery success is validated operationally rather than through a dedicated F1AP confirm message.

Typical state: The key evidence is correct command decode, DU radio broadcast, and UE acquisition of the requested SI.

Preconditions:

System Information Delivery Command contains Transaction ID, NR CGI, SIType List, and Confirmed UE ID.
DU broadcast logs or radio traces are available.

Next likely message: UE acquires requested SI, or troubleshooting continues at DU broadcast and RRC SI acquisition layers

Avoiding message confusion

5G F1AP validation diagram showing command fields, DU broadcast logs, UE SI acquisition, Error Indication, and gNB-DU Configuration Update — Troubleshooting branch: validate the command, DU broadcast, UE acquisition, and applicable F1AP error or reporting paths.

Call flow position: Do not confuse this expected confirm with PWS responses, gNB-DU Configuration Update Acknowledge, or vendor-internal acknowledgements.

Typical state: Those messages have their own procedures and do not turn System Information Delivery Confirm into a standard F1AP PDU.

Preconditions:

A decoder or implementation note may use informal acknowledgement wording.

Next likely message: Map the trace to the actual F1AP PDU names before drawing call-flow conclusions

Call flow position

Previous message(s): System Information Delivery Command, DU receives requested SI broadcast instruction, Trace analyst expects SI success evidence

Next message(s): DU broadcasts requested SI over NR radio, gNB-DU Configuration Update if dedicated SI delivery is needed, Error Indication if protocol handling fails

Message direction and transport

Sender and receiver: Not a standalone F1AP PDU in TS 38.473 Release 18

Interface: F1-C

Domain: System information management and NR broadcast validation

Signaling bearer: No standalone System Information Delivery Confirm signalling bearer

Logical channel: Not applicable as a separate F1AP message

Transport / encapsulation: F1AP over SCTP/IP for the System Information Delivery Command procedure

Security context: No security context is established by a separate confirm message because the confirm PDU is not defined in TS 38.473 Release 18.

Message Structure Overview

TS 38.473 Release 18 defines System Information Delivery Command, not a separate System Information Delivery Confirm message.
The command message carries Transaction ID, NR CGI, SIType List, and Confirmed UE ID.
Do not wait for a successfulOutcome confirm PDU when validating this procedure.
Validate success by checking DU broadcast of the requested SI and UE RRC SI acquisition behavior.
If dedicated SI delivery is needed, related reporting may appear through gNB-DU Configuration Update handling.

ASN.1 for System Information Delivery Confirm

-- No standalone SystemInformationDeliveryConfirm PDU is defined
-- in TS 38.473 Release 18.

SystemInformationDeliveryCommand ::= SEQUENCE {
  protocolIEs ProtocolIE-Container { {SystemInformationDeliveryCommandIEs} },
  ...
}

SystemInformationDeliveryCommandIEs F1AP-PROTOCOL-IES ::= {
  { Message Type, mandatory } |
  { Transaction ID, mandatory } |
  { NR CGI, mandatory } |
  { SIType List, mandatory } |
  { Confirmed UE ID, mandatory },
  ...
}

How to read this ASN.1

Use this ASN.1 block as the guardrail: the standard command exists, but a separate System Information Delivery Confirm PDU does not appear in the Release 18 ASN.1.

System Information Delivery Confirm - Example Dump

Expected trace pattern:

F1AP-PDU
  initiatingMessage
    procedureCode: id-SystemInformationDeliveryCommand
    value: SystemInformationDeliveryCommand
      protocolIEs:
        - id: id-TransactionID
          value: 18
        - id: id-NRCGI
          value: 00101-000000321
        - id: id-SItype-List
          value: [sib2, sib4]
        - id: id-ConfirmedUEID
          value: 49217

No standard F1AP-PDU:
  successfulOutcome
    value: SystemInformationDeliveryConfirm

Validation evidence:
  DU radio log: requested SI scheduled and broadcast
  UE trace: requested SI acquired or SI acquisition failure observed
  Optional follow-up: Error Indication or gNB-DU Configuration Update if applicable

How to read this dump

Treat this as a teaching example, not as a captured network trace.
If a decoder shows System Information Delivery Confirm, verify whether it is a vendor label, private extension, or a mistaken mapping.
Use the command Transaction ID for trace correlation, but do not expect a matching standard confirm PDU.

Important Information Elements

IE	Presence	Description
`Message Type`	Optional	No standard SYSTEM INFORMATION DELIVERY CONFIRM message type is defined in TS 38.473 Release 18.
`Transaction ID`	Optional	There is no confirm Transaction ID. Correlate the original System Information Delivery Command Transaction ID instead.
`Criticality Diagnostics`	Optional	There is no Criticality Diagnostics IE for a standalone confirm PDU. Protocol problems may appear through Error Indication or procedure-specific handling.

Detailed field explanation

`Message Type`

No standard SYSTEM INFORMATION DELIVERY CONFIRM message type is defined in TS 38.473 Release 18.

Presence: Optional

In practice: In practice, compare this field with the original request and with any later release-dependent optional fields so you can see whether the network accepted the same service model the UE asked for.

`Transaction ID`

There is no confirm Transaction ID. Correlate the original System Information Delivery Command Transaction ID instead.

Presence: Optional

In practice: In practice, compare this field with the original request and with any later release-dependent optional fields so you can see whether the network accepted the same service model the UE asked for.

`Criticality Diagnostics`

There is no Criticality Diagnostics IE for a standalone confirm PDU. Protocol problems may appear through Error Indication or procedure-specific handling.

Presence: Optional

In practice: In practice, compare this field with the original request and with any later release-dependent optional fields so you can see whether the network accepted the same service model the UE asked for.

What to check in logs and traces

Confirm the preceding System Information Delivery Command is present.
Decode Transaction ID, NR CGI, SIType List, and Confirmed UE ID in the command.
Do not mark the trace failed solely because there is no System Information Delivery Confirm.
Check DU logs to confirm the requested SI was scheduled for broadcast.
Check radio traces or UE logs to confirm requested SI acquisition.
Look for Error Indication if the DU could not handle the command.
Look for gNB-DU Configuration Update dedicated-SI reporting when the UE cannot receive SI from broadcast.

Common Issues and Troubleshooting

Expected System Information Delivery Confirm is missing.

Likely cause: The expected message is not defined as a standalone F1AP PDU in TS 38.473 Release 18.

What to inspect: Check the preceding System Information Delivery Command and DU broadcast evidence instead.

Next step: Update the call-flow expectation to command followed by radio SI broadcast or applicable error/reporting procedures.

A decoder displays System Information Delivery Confirm.

Likely cause: The label may come from a vendor extension, internal event, old parser assumption, or mistaken procedure mapping.

What to inspect: Compare procedureCode, PDU type, and IE list with TS 38.473 ASN.1.

Next step: Treat it as non-standard until the actual encoded PDU is verified.

SI still appears stale after the command.

Likely cause: The issue is likely DU broadcast scheduling, wrong NR CGI, wrong SIType List, or UE SI acquisition behavior, not a missing confirm.

What to inspect: Check NR CGI, SIType List, DU broadcast logs, RRC SI scheduling, and UE acquisition traces.

Next step: Troubleshoot the broadcast and RRC acquisition path.

LTE / 5G / Variant Comparison

Compared with System Information Delivery Command

The command is the standard F1AP message. A separate confirm PDU is not defined in TS 38.473 Release 18.

Compared with Paging

Paging is a real CU-to-DU F1AP message for UE reachability. SI Delivery Confirm is only a common expectation or label, not a standard paging-like message.

Compared with gNB-DU Configuration Update Acknowledge

gNB-DU Configuration Update Acknowledge is a real response for DU configuration updates. It does not confirm System Information Delivery Command.

FAQ

What is System Information Delivery Confirm in F1AP?

It is not defined as a standalone F1AP message in TS 38.473 Release 18. Use this page as a clarification when a trace workflow expects one.

Who sends this message?

No standard gNB-DU-to-gNB-CU System Information Delivery Confirm PDU is defined in TS 38.473 Release 18.

What does Transaction ID do?

Transaction ID exists in System Information Delivery Command. There is no separate confirm Transaction ID to match.

Does this message confirm SI broadcast success?

No standard confirm message does that. Confirm SI handling through DU broadcast logs, radio traces, and UE RRC SI acquisition.

What is Criticality Diagnostics used for?

Criticality Diagnostics is used by many F1AP messages, but it is not part of a standalone SI Delivery Confirm in TS 38.473 Release 18.

How is this different from Paging?

Paging is a real F1AP message for UE reachability. SI Delivery Confirm is not a standard F1AP message.

How is this different from gNB-DU Configuration Update Acknowledge?

gNB-DU Configuration Update Acknowledge is a real acknowledgement for DU configuration updates; it does not serve as an SI Delivery Confirm.

How do you troubleshoot SI delivery confirmation issues?

Start with System Information Delivery Command, verify NR CGI and SIType List, then check DU broadcast logs, UE SI acquisition, Error Indication, and any related gNB-DU Configuration Update.

References

3GPP TS 38.473
System Information Delivery procedure
System Information Delivery Command
3GPP TS 38.331

Related message pages

Related Tools

Use This Reference in Practice

Decode this message with the 3GPP Decoder, inspect the related message database, or open the matching call flow to see where this signaling step fits in the full procedure.