| Protocol | nas | Network | lte |
|---|---|---|---|
| Spec | 3GPP TS 24.301 | Spec Section | 6.4.3, 8.3.16 |
| Direction | UE to MME | Message Type | ESM signaling |
| Full message name | LTE Modify EPS Bearer Context Accept |
|---|---|
| Protocol | NAS |
| Technology | LTE |
| Direction | UE to MME |
| Interface | N1 over LTE access / S1-MME control path |
| Signaling bearer / channel | NAS signaling / Sent immediately after Modify EPS Bearer Context Request in the same bearer-update branch. |
| Typical trigger | Triggered when the UE successfully applies the bearer changes from Modify EPS Bearer Context Request. |
| Main purpose | Confirms that the UE accepted the new bearer parameters and completed the live bearer modification branch. |
| Main specification | 3GPP TS 24.301, 6.4.3, 8.3.16 |
| Release added | Release 8 |
| Procedures where used | Modify EPS Bearer Context Procedure |
Modify EPS Bearer Context Accept is the LTE NAS message the UE sends after it applied the bearer update requested by the network.
Confirms that the UE accepted the new bearer parameters and completed the live bearer modification branch.
Modify EPS Bearer Context Accept is the UE saying it applied the requested bearer update.
Call flow position: UE acknowledgment that the network-driven QoS or AMBR update was accepted.
Typical state: The bearer remains active and now uses the updated definition.
Preconditions:
Next likely message: Later bearer traffic using the new settings
Call flow position: UE acknowledgment that the requested TFT or filter update was accepted.
Typical state: The bearer remains active with updated packet-handling rules.
Preconditions:
Next likely message: Later bearer traffic using the new rules
Previous message(s): Modify EPS Bearer Context Request
Next message(s): Later user-plane traffic under the new bearer definition
Security context: Protected by the active NAS security context because it confirms a live bearer change.
Modify EPS Bearer Context Accept
Protocol configuration options OPTIONAL
NBIFOM container OPTIONAL
Extended protocol configuration options OPTIONAL
This message is mostly procedural. Read it as the completion point of the bearer update.
Modify EPS Bearer Context Accept
Protocol discriminator: EPS session management
EPS bearer identity: 6
Procedure transaction identity: 5
Message type: Modify EPS Bearer Context Accept
| IE | Required | Description |
|---|---|---|
Protocol configuration options | Optional | May return associated configuration data when the UE includes response-side configuration detail. |
Protocol configuration optionsMay return associated configuration data when the UE includes response-side configuration detail.
Presence: Optional
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: Modify EPS Bearer Context Accept may be missing or not received.
What to inspect: Check the request-accept pair and later bearer behavior.
Next step: Treat the problem as incomplete bearer-update signaling before blaming policy logic.
It is the UE message that confirms an active bearer update was accepted and applied.
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.