| Protocol | nas | Network | lte |
|---|---|---|---|
| Spec | 3GPP TS 24.301 | Spec Section | 6.6.1.2, 8.3.13 |
| Direction | MME to UE | Message Type | ESM signaling |
| Full message name | LTE ESM Information Request |
|---|---|
| Protocol | NAS |
| Technology | LTE |
| Direction | MME to UE |
| Interface | N1 over LTE access / S1-MME control path |
| Signaling bearer / channel | NAS signaling / Sent only after NAS security is in place when the ESM information transfer flag requires a follow-up exchange. |
| Typical trigger | Triggered when the PDN Connectivity Request set the ESM information transfer flag and the network still needs APN or protocol configuration details. |
| Main purpose | Requests APN and protocol configuration information from the UE after the PDN Connectivity Request indicated that a protected ESM information exchange is needed. |
| Main specification | 3GPP TS 24.301, 6.6.1.2, 8.3.13 |
| Release added | Release 8 |
| Procedures where used | ESM Information Request Procedure, UE Requested PDN Connectivity Procedure, LTE Attach Procedure |
| Related timers | T3489 |
ESM Information Request is the LTE NAS session-management message the network sends when it needs protected APN or protocol configuration details before completing PDN handling.
Requests APN and protocol configuration information from the UE after the PDN Connectivity Request indicated that a protected ESM information exchange is needed.
ESM Information Request means the network needs more protected PDN setup detail before it can continue.
Call flow position: Network request sent after attach-related security setup when the embedded PDN branch still needs protected APN or protocol options.
Typical state: The UE is not yet finished with PDN handling because the network is waiting for more ESM detail.
Preconditions:
Next likely message: ESM Information Response
Call flow position: Network request sent during a standalone PDN-connectivity branch after the UE asked for another PDN or APN.
Typical state: The PDN establishment is paused until the UE returns the requested APN or protocol data.
Preconditions:
Next likely message: ESM Information Response
Previous message(s): PDN Connectivity Request, Authentication Request, Security Mode Command
Next message(s): ESM Information Response, PDN Connectivity Reject, Activate Default EPS Bearer Context Request
Security context: Sent only after the security context has been set up because the requested information may need protected transfer.
ESM Information Request
This ESM message is structurally simple. The real value is procedural: it tells you the network still needs protected APN or configuration detail.
ESM Information Request
Protocol discriminator: EPS session management
EPS bearer identity: 0
Procedure transaction identity: 3
Message type: ESM Information Request
Likely cause: The network may still be waiting for APN or protocol details through the ESM information exchange.
What to inspect: Check PDN Connectivity Request, ESM Information Request, and the later ESM Information Response.
Next step: Treat the branch as pending ESM detail exchange before blaming bearer activation.
PDN Connectivity Request starts the branch. ESM Information Request asks for the missing protected detail the network still needs.
It is the network message asking the UE for protected APN or protocol configuration detail before PDN setup continues.
Because it explains why PDN setup can pause after security setup even though the branch has not failed.
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.