| Protocol | nas | Network | 5g |
|---|---|---|---|
| Spec | 3GPP TS 24.501 | Spec Section | 8.2.27 |
| Direction | AMF to UE | Message Type | 5GMM signaling |
| Full message name | 5G NAS - Notification |
|---|---|
| Protocol | NAS |
| Technology | 5G |
| Direction | AMF to UE |
| Interface | N1 |
| Signaling bearer / channel | NAS signaling / Dedicated NAS message, commonly transported via DL Information Transfer |
| Typical trigger | Sent when the network needs to notify the UE of a mobility-management-related event that requires explicit NAS-level indication. |
| Main purpose | Provides a short network-to-UE indication so the UE can react to a mobility-management-related notification and, when required, answer with Notification Response. |
| Main specification | 3GPP TS 24.501, 8.2.27 |
| Release added | Release 15 |
| Procedures where used | Protected 5GMM signaling, Registration follow-on handling, Service-context notification handling |
Notification is the NAS message the network sends to inform the UE about an event that requires the UE's attention in the current mobility-management context.
Provides a short network-to-UE indication so the UE can react to a mobility-management-related notification and, when required, answer with Notification Response.
Notification is the network sending the UE a short NAS indication that usually expects a simple response.
Call flow position: Network indication step during an already established NAS signaling context.
Typical state: UE is already known to the network and the AMF needs to deliver a short mobility-management notification.
Preconditions:
Next likely message: Notification Response or later NAS handling
Call flow position: Supplementary notification branch after normal registration or service signaling has already been established.
Typical state: The main access procedure succeeded, but the network still needs to explicitly notify the UE about a follow-on condition.
Preconditions:
Next likely message: Notification Response
Previous message(s): Registration Accept, Service Accept, Ongoing protected NAS procedure
Next message(s): Notification Response, Further protected NAS signaling
Security context: Usually appears when a NAS security context already exists, so engineers should confirm that the message protection state matches the wider 5GMM procedure.
This message is not typically analyzed as ASN.1 on the wire. It is usually read as a NAS or protocol field structure instead.
Notification follows NAS 24.501 IE structure and is not an ASN.1 message.
Notification
Extended Protocol Discriminator: 5G Mobility Management
Security Header Type: Integrity protected and ciphered
Message Type: Notification
Access Type: 3GPP access
| IE | Required | Description |
|---|---|---|
Access type | Yes | Indicates the access-related context for the notification so the UE interprets the message in the right signaling scope. |
Access typeIndicates the access-related context for the notification so the UE interprets the message in the right signaling scope.
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 AMF may be signaling an access-related condition that requires explicit UE acknowledgement.
What to inspect: Check the preceding NAS state, the message protection, and whether the UE answers with Notification Response.
Next step: Follow the trace into Notification Response and the next protected NAS message to understand the operational impact.
Likely cause: The UE may not have accepted or correctly processed the protected NAS indication, or the uplink response was not delivered.
What to inspect: Check lower-layer delivery, NAS protection, and whether the UE stayed in the expected 5GMM state.
Next step: Compare with a known-good protected NAS trace and confirm that the UE recognized the notification context.
It lets the network send the UE a short mobility-management-related indication during protected NAS signaling.
The UE typically responds with Notification Response and the wider NAS procedure continues.
No. It is an indication message. Engineers should decide whether it is normal or abnormal based on the surrounding NAS procedure context.
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.