RRC 5G UE -> gNB 3GPP TS 38.331

5G NR - RRC Resume Request

RRC Resume Request is the UE-to-network NR RRC message used to request resumption of a suspended or inactive context.

Message Fact Sheet

Protocol	rrc	Network	5g
Spec	3GPP TS 38.331	Spec Section	5.3.13, 6.2.2
Direction	UE -> gNB	Message Type	Connection Resume

Full message name	5G NR - RRC Resume Request
Protocol	RRC
Technology	5G
Direction	UE -> gNB
Interface	Uu
Signaling bearer / channel	SRB0 / UL-CCCH
Typical trigger	Used when the UE has an inactive or suspended context and needs to return to connected mode.
Main purpose	Starts the resume procedure so the network can restore the earlier connected context instead of creating a fresh setup.
Main specification	3GPP TS 38.331, 5.3.13, 6.2.2
Release added	Release 15
Procedures where used	RRC Resume, Paging Response from Inactive, Inactive-to-Connected Transition
Related timers	T380
Related cause values	mo-Signalling, mo-Data, mt-Access

What is RRC Resume Request in simple terms?

RRC Resume Request is the UE-to-network NR RRC message used to request resumption of a suspended or inactive context.

Starts the resume procedure so the network can restore the earlier connected context instead of creating a fresh setup.

Why this message matters

RRC Resume Request asks the network to restore a previous inactive or suspended context.

Where this message appears in the call flow

RRC Resume

Call flow position: First UE message in the resume path.

Typical state: UE is in RRC_INACTIVE or suspended state.

Preconditions:

A valid inactive or suspended context exists.

Next likely message: RRC Resume or RRC Reject

Call flow position

Previous message(s): Paging, Resume trigger from upper layers

Next message(s): RRC Resume, RRC Reject

Message direction and transport

Sender and receiver: UE -> gNB

Interface: Uu

Domain: Access-side radio control

Signaling bearer: SRB0

Logical channel: UL-CCCH

Transport / encapsulation: Early resume signaling before the restored dedicated context exists

Security context: Sent before full connected context is restored.

Message Structure Overview

This message is the resume-path equivalent of a fresh setup request.

ASN.1 for 5G NR - RRC Resume Request

RRCResumeRequest ::= SEQUENCE {
  criticalExtensions CHOICE {
    rrcResumeRequest RRCResumeRequest-IEs,
    ...
  }
}

How to read this ASN.1

The key checks are which resume identity was used and whether the resume cause matches the scenario.

Decoded Message Dump

UL-CCCH-Message
  message: rrcResumeRequest
    resumeCause: mo-Data

How to read this dump

The resume cause should line up with the user or network event that triggered the resume.

Important Information Elements

IE	Required	Description
`resumeIdentity`	Yes	Identifies the suspended or inactive UE context to be resumed.
`resumeCause`	Yes	Explains why the UE is requesting the resume.

Detailed field explanation

`resumeIdentity`

Identifies the suspended or inactive UE context to be resumed.

Presence: Required

`resumeCause`

Explains why the UE is requesting the resume.

Presence: Required

What to check in logs and traces

Check whether a prior inactive context really existed.
Correlate the resume request with any paging or upper-layer trigger.

Common Issues and Troubleshooting

The UE falls back to fresh setup instead of resuming.

Likely cause: The resume identity may be missing, stale, or rejected.

What to inspect: Check the resume request and the immediate network response.

Next step: Compare it with any paging context and later setup behavior.

Detailed explanation

5G NR - RRC Resume Request Explained

RRC Resume Request is a 5G NR RRC message reference page for engineers who need to understand what the message carries, where it fits in the procedure, and what to inspect in traces when behavior does not match expectation.

RRC Resume Request is the UE-to-network NR RRC message used to request resumption of a suspended or inactive context. Starts the resume procedure so the network can restore the earlier connected context instead of creating a fresh setup.

What is RRC Resume Request in simple terms?

RRC Resume Request is the uplink NR RRC message the UE sends to the network when this specific procedure step needs to be requested, reported, or confirmed.

Starts the resume procedure so the network can restore the earlier connected context instead of creating a fresh setup.

Why this message matters

it directly affects RRC Resume, Paging Response from Inactive and the surrounding RRC workflow
The UE falls back to fresh setup instead of resuming
Used when the UE has an inactive or suspended context and needs to return to connected mode

Where this message appears in the call flow

RRC Resume Request is typically seen during RRC Resume. Engineers usually read it together with the messages just before and just after it so they can tell whether the procedure is progressing normally or drifting into a fallback or failure path.

The UE is usually in in RRC_INACTIVE or suspended state when engineers evaluate this message in traces. In the main procedure context, it appears first UE message in the resume path. Before this message appears, the important preconditions are A valid inactive or suspended context exists..

Simplified sequence:

UE                       gNB / Network
|                        |
|<-- Paging -----------|
|--- RRC Resume Request ----------->|
|<-- RRC Resume -----------|

Message direction and transport

sender: UE
receiver: gNB
interface: Uu
signaling bearer: SRB0
signaling channel: UL-CCCH
transport type: Early resume signaling before the restored dedicated context exists
domain: Access-side radio control
security context: Sent before full connected context is restored.

Important Information Elements

IE	Why it matters
`resumeIdentity`	Identifies the suspended or inactive UE context to be resumed.
`resumeCause`	Explains why the UE is requesting the resume.

Example message dump

UL-CCCH-Message
  message: rrcResumeRequest
    resumeCause: mo-Data

How to read this dump

The resume cause should line up with the user or network event that triggered the resume.

FAQ

What happens after RRC Resume Request?

The network normally answers with RRC Resume if it accepts the request.

Summary

RRC Resume Request is the UE-to-network NR RRC message used to request resumption of a suspended or inactive context.

Advanced Engineer Notes

This message is one of the main places to debug context mismatch between UE and network.

Related message pages

Related Procedures

Related Tools

Use This Reference in Practice

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.