| Protocol | nas | Network | 5g |
|---|---|---|---|
| Spec | 3GPP TS 24.501 | Spec Section | 8.2.18 |
| Direction | UE to AMF | Message Type | 5GMM signaling |
| Full message name | 5G NAS - Control Plane Service Request |
|---|---|
| Protocol | NAS |
| Technology | 5G |
| Direction | UE to AMF |
| Interface | N1 |
| Signaling bearer / channel | NAS signaling / Dedicated NAS message |
| Typical trigger | Used in control-plane service scenarios where NAS signaling continuation is needed without a standard user-plane service path. |
| Main purpose | Provides a control-plane service request path for scenarios where NAS signaling itself must be delivered using existing registration context. |
| Main specification | 3GPP TS 24.501, 8.2.18 |
| Release added | Release 15 |
| Procedures where used | Control Plane Service Request |
Control Plane Service Request is the NAS message used when the UE requests control-plane service handling without the normal user-plane service path.
Provides a control-plane service request path for scenarios where NAS signaling itself must be delivered using existing registration context.
This is a specialized NAS request used when the UE needs control-plane service continuation.
Call flow position: UE-originated NAS request for control-plane-only service handling.
Typical state: UE is registered and needs control-plane service continuation.
Preconditions:
Next likely message: DL NAS transport or further NAS control-plane activity
Previous message(s): Paging, Resume or access signaling
Next message(s): DL NAS Transport, Further control-plane signaling
Security context: Normally protected because it relies on existing NAS context.
This message is not typically analyzed as ASN.1 on the wire. It is usually read as a NAS or protocol field structure instead.
This is a NAS 24.501 message.
Control Plane Service Request
Extended Protocol Discriminator: 5G Mobility Management
Security Header Type: Integrity protected and ciphered
Message Type: Control Plane Service Request
| IE | Required | Description |
|---|---|---|
Service type / control-plane context | Yes | Explains the specific control-plane service request intent. |
Service type / control-plane contextExplains the specific control-plane service request intent.
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 issue may be in the follow-on NAS transport or in the network's handling of control-plane service context.
What to inspect: Check subsequent DL NAS Transport, AMF handling, and the exact service scenario.
Next step: Compare with standard Service Request behavior and verify the intended control-plane use case.
It is a specialized NAS request used when the UE needs control-plane service handling using existing registration 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.