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.
| 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. |
| Main specification | 3GPP TS 24.501, 8.2.2 |
| Release added | Release 15 |
| Procedures where used | 5G Initial Registration, 5G Authentication Procedure |
| Related timers | T3560 |
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.
Authentication Response is the UE answering the network's authentication challenge.
Call flow position: UE response to the network's authentication challenge.
Typical state: UE is in the middle of primary authentication.
Preconditions:
Next likely message: Authentication Result, Security Mode Command, or later registration continuation
Previous message(s): Authentication Request
Next message(s): Authentication Result, Security Mode Command, Registration Accept
Security context: Often sent before full NAS security is active in fresh registration procedures.
This message is not typically analyzed as ASN.1 on the wire. It is usually read as a NAS or protocol field structure instead.
Authentication Response is a NAS 24.501 message, not an ASN.1-defined message.
Authentication Response
Extended Protocol Discriminator: 5G Mobility Management
Security Header Type: Plain NAS
Message Type: Authentication Response
Authentication Response Parameter: 0x87c143f5e3a11022aabbccddeeff0011
| 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. |
Authentication response parameterUE-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 messageCarries 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.
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.
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.