| Protocol | nas | Network | 5g |
|---|---|---|---|
| Spec | 3GPP TS 24.501 | Spec Section | 8.2.36 |
| Direction | Network to UE | Message Type | 5GMM signaling |
| Full message name | 5G NAS - Relay Key Reject |
|---|---|
| Protocol | NAS |
| Technology | 5G |
| Direction | Network to UE |
| Interface | N1 |
| Signaling bearer / channel | NAS signaling / Dedicated NAS message, transported over the existing NAS path |
| Typical trigger | Sent when the network cannot accept the relay key request or cannot provide valid relay-related key response information. |
| Main purpose | Rejects the relay key request and carries the cause information needed to explain why relay key handling could not continue. |
| Main specification | 3GPP TS 24.501, 8.2.36 |
| Release added | Release 17 |
| Procedures where used | Relay key procedure, Relay security handling, ProSe relay context |
| Related cause values | 5GMM cause |
Relay Key Reject is the NAS message the network sends when the relay key request cannot be accepted and the relay-related key procedure must stop or take a failure branch.
Rejects the relay key request and carries the cause information needed to explain why relay key handling could not continue.
Relay Key Reject means the network could not accept the relay key request and the relay key procedure failed.
Call flow position: Negative response branch after Relay Key Request.
Typical state: The relay-aware NAS context exists, but the network rejected the relay key request.
Preconditions:
Next likely message: Procedure abort or retry
Call flow position: Network reject step when relay-key response processing cannot continue.
Typical state: The relay security branch failed before successful relay-key response delivery.
Preconditions:
Next likely message: Procedure retry or feature fallback
Previous message(s): Relay Key Request, Relay authentication context establishment
Next message(s): Relay procedure abort, Procedure retry with corrected context
Security context: This message belongs to the relay-key handling failure branch, so it should be interpreted together with the earlier Relay Key Request, relay transaction identity, and the reject cause.
This message is not typically analyzed as ASN.1 on the wire. It is usually read as a NAS or protocol field structure instead.
Relay Key Reject follows NAS 24.501 IE structure and is not an ASN.1 message.
Relay Key Reject
Extended Protocol Discriminator: 5G Mobility Management
Security Header Type: Integrity protected and ciphered
Message Type: Relay Key Reject
ProSe Relay Transaction Identity: 7
5GMM Cause: Semantically incorrect message
| IE | Required | Description |
|---|---|---|
ProSe relay transaction identity | Yes | Identifies the relay-key transaction so the reject can be matched with the earlier request. |
5GMM cause | Yes | Explains why the network rejected the relay key request. |
ProSe relay transaction identityIdentifies the relay-key transaction so the reject can be matched with the earlier request.
Presence: Required
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.
5GMM causeExplains why the network rejected the relay key request.
Presence: Required
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.
Likely cause: The relay request parameters or relay context were not acceptable to the network.
What to inspect: Check the relay transaction identity, request parameters in Relay Key Request, and the 5GMM cause returned in the reject.
Next step: Compare the relay request against a known-good trace and verify relay feature support and transaction correctness.
Likely cause: The failure belongs to the relay-specific key branch rather than to the general NAS path.
What to inspect: Focus on relay-context correlation and the reject cause rather than on mainstream registration signaling.
Next step: Treat the relay-key failure as a specialized feature problem and trace the feature-specific branch.
It tells the UE that the relay key request failed and provides the cause for that failure.
No. It belongs to a specialized relay security procedure rather than the standard registration path.
Start with the relay transaction identity and the 5GMM cause.
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.