Authentication Response is the UE's NAS reply to Authentication Request, carrying the computed response or EAP data needed for subscriber verification.
Message Fact Sheet
Protocol
nas
Network
5g
Spec
3GPP TS 24.501
Spec Section
8.2.2
Direction
UE to AMF
Message Type
5GMM signaling
Full message name
5G NAS - Authentication Response
Protocol
NAS
Technology
5G
Direction
UE to AMF
Interface
N1
Signaling bearer / channel
NAS signaling / Dedicated NAS message, commonly via UL Information Transfer
Typical trigger
Sent after the UE successfully processes Authentication Request.
Main purpose
Lets the UE prove subscriber legitimacy so the network can continue registration and later activate NAS security.
Authentication Response is the UE's NAS reply to Authentication Request, carrying the computed response or EAP data needed for subscriber verification.
Lets the UE prove subscriber legitimacy so the network can continue registration and later activate NAS security.
Why this message matters
Authentication Response is the UE answering the network's authentication challenge.
Where this message appears in the call flow
5G Authentication Procedure
Call flow position: UE response to the network's authentication challenge.
Typical state: UE is in the middle of primary authentication.
Preconditions:
The UE received a valid Authentication Request.
Next likely message: Authentication Result, Security Mode Command, or later registration continuation
The exact payload interpretation depends on whether the procedure is 5G AKA or EAP based.
Important Information Elements
IE
Required
Description
Authentication response parameter
Optional
UE-computed response parameter used in 5G AKA challenge handling.
EAP message
Optional
Carries the UE's EAP response in EAP-based primary authentication.
Detailed field explanation
Authentication response parameter
UE-computed response parameter used in 5G AKA challenge 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.
EAP message
Carries the UE's EAP response in EAP-based primary authentication.
Presence: Optional
In practice: If present, it reflects the external DN authentication result. It is worth checking when the session succeeds on NAS but service access still depends on an external authentication flow.
What to check in logs and traces
Confirm the message follows Authentication Request without abnormal delay.
Check whether the response format matches the authentication method in use.
Correlate the response with the later Authentication Result or Security Mode Command.
Common Issues and Troubleshooting
Authentication Request is visible but Authentication Response never arrives.
Likely cause: UE challenge processing failed, radio signaling broke before the uplink response, or the trace misses the UL segment.
What to inspect: Check UE logs, UL NAS transport, and any concurrent Authentication Failure.
Next step: Verify whether the UE rejected AUTN, lost radio connectivity, or timed out.
FAQ
What comes after Authentication Response in 5G?
The network may send Authentication Result, continue directly into Security Mode Command, or terminate the procedure depending on the method and outcome.
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.