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LTE Bearer Release Procedure Call Flow

call-flowLTE | EPC | NAS | GTPv2-C

LTE Bearer Release Procedure removes an EPS bearer that was previously active. It appears when the network no longer wants to keep that bearer alive because service ended, policy changed, a dedicated bearer is no longer needed, or the session is moving toward teardown.

The main NAS pair is Deactivate EPS Bearer Context Request and Deactivate EPS Bearer Context Accept.

Introduction

The bearer release branch is the inverse of bearer activation. It removes an existing bearer context while the rest of the PDN session may either continue or move toward a broader disconnect path.

The main nodes are the UE, MME, SGW, and PGW. The eNB may also release matching access-side resources after the bearer is removed.

What Is LTE Bearer Release Procedure in Simple Terms?

What starts the procedure: The network decides an active bearer should be removed.
What the UE and network want to achieve: Cleanly deactivate the bearer while keeping state aligned across the UE and EPC.
What success looks like: The UE receives Deactivate EPS Bearer Context Request and returns Deactivate EPS Bearer Context Accept.
What failure means: The bearer is removed only partially or later traces still show stale bearer context.

Why this procedure matters

This procedure explains why a bearer disappears from a live session and how to separate normal release from failure-led teardown.

Quick Fact Sheet

Procedure name	LTE Bearer Release Procedure
Domain	EPS bearer deactivation
Main trigger	Service ends or the network removes a bearer
Start state	UE has an active bearer that the network wants to release
End state	The target bearer is no longer active
Main nodes	UE, MME, SGW, PGW
Main protocols	NAS, GTPv2-C
Main success outcome	The bearer is cleanly removed from UE and EPC context
Main failure outcome	Bearer state becomes stale or only partially released
Most important messages	Deactivate EPS Bearer Context Request, Deactivate EPS Bearer Context Accept
Main specs	TS 24.301, TS 23.401, TS 29.274

LTE Bearer Release Procedure call flow across UE, MME, SGW, and PGW — Click the diagram to open the full-size in a new tab.

Preconditions

The bearer already exists and is active.
The EPC has a reason to remove that bearer.
The UE and network still share enough context to identify the bearer cleanly.

Nodes and Interfaces

Nodes involved

Node	Role in this procedure
UE	Removes the target bearer context when deactivation is accepted.
MME	Delivers the deactivation request toward the UE.
SGW	Releases serving-side bearer state.
PGW	Releases or updates PDN-side bearer state.

Interfaces used

Interface	Path	Role
S11	MME <-> SGW	Coordinates EPC bearer removal.
S5/S8	SGW <-> PGW	Releases the PDN-side bearer relation.
NAS	UE <-> MME	Carries the bearer deactivation pair.

End-to-End Call Flow

UE               MME               SGW               PGW
|                 |                 |-- Bearer release ->|
|                 |                 |<-- Release result --|
|<- Deactivate EPS Bearer Ctx Req --|                    |
|-- Deactivate EPS Bearer Ctx Accept ->|                 |
|   bearer is removed from the session |                 |

Major Phases

Phase	What happens
1. Release decision	The EPC decides the active bearer should be removed.
2. NAS deactivation	The MME sends the bearer deactivation to the UE.
3. UE confirmation	The UE confirms that the bearer context was removed.

Step-by-Step Breakdown

Step 1: Release handling in the EPC

Sender -> receiver: PGW -> SGW -> MME

Message(s): GTPv2-C bearer release handling

Purpose: Remove the live bearer from the EPC side.

State or context change: The control plane is ready to tell the UE to delete the bearer.

Note: This is where normal release and failure-led release often start to diverge.

Step 2: Deactivate bearer context

Sender -> receiver: MME -> UE

Message(s): Deactivate EPS Bearer Context Request

Purpose: Tell the UE which bearer must be removed.

State or context change: The UE starts deleting the target bearer context.

Note: EBI and any included cause values are the first checks.

Step 3: UE accept

Sender -> receiver: UE -> MME

Message(s): Deactivate EPS Bearer Context Accept

Purpose: Confirm the bearer was removed.

State or context change: The bearer is no longer active in UE context.

Note: Missing accept often leaves stale context in multi-layer traces.

Important Messages in This Flow

Message	Protocol	Direction	Purpose in this procedure	What to inspect briefly
Deactivate EPS Bearer Context Request	NAS	MME -> UE	Starts bearer removal at the UE side.	EBI, included cause, and whether the release is normal or failure-led.
Deactivate EPS Bearer Context Accept	NAS	UE -> MME	Confirms bearer deactivation.	Return timing and correlation to the same bearer identity.

Important Parameters to Inspect

Parameter	What it is	Where it appears	Why it matters	Common issues
EPS Bearer ID	The bearer being removed.	Deactivate request and accept	Shows exactly which bearer is leaving the session.	Wrong bearer released or mismatched correlation.
ESM cause	The reason attached to the deactivation branch when present.	Deactivate request	Helps separate normal cleanup from failure handling.	Cause interpretation errors.
PTI	The ESM transaction identity.	NAS deactivation handling	Helps align the release with earlier session transactions.	PTI mismatch.

Successful Completion

Success is confirmed when the UE accepts the deactivation request and the target bearer disappears from both UE and EPC context views.

Common Failures and Troubleshooting

Symptom	Likely cause	Where to inspect	Relevant message(s)	Relevant interface(s)	Likely next step
Deactivate request appears, but bearer still looks active later	UE did not apply the release or later cleanup was incomplete.	EBI continuity before and after the request.	Deactivate EPS Bearer Context Request	NAS, later bearer context checks	Confirm whether the accept returned and whether the EPC also closed the bearer.
Release looks like a failure instead of normal cleanup	Cause value points to network or bearer error handling.	Included cause and preceding bearer events.	Deactivate request and earlier failure branch	NAS, S11, S5/S8	Trace backward to the first failing update or bearer-control step.

What to Check in Logs and Traces

Check the release reason before assuming the bearer was removed normally.
Track the EBI from activation through deactivation to confirm the right bearer was released.
Confirm the UE-side accept and EPC-side release branch both completed.

Related sub-procedures

Related message reference pages

Related troubleshooting pages

Notes

Bearer release can be normal or failure-led. The included cause and the earlier bearer history decide which branch you are looking at.

FAQ

What is LTE Bearer Release Procedure?

It is the procedure that removes an active EPS bearer from the UE and EPC context.

Which message is the clearest start of the release?

Deactivate EPS Bearer Context Request is the clearest UE-side start of the deactivation branch.