LTE RRC CSFB Parameters Response CDMA2000

Message Fact Sheet

Protocol	lte-rrc	Network	lte
Spec	3GPP TS 36.331	Spec Section	5.3.5, 6.2.2
Direction	UE -> eNodeB	Message Type	Interworking / CSFB

Full message name	LTE RRC CSFB Parameters Response CDMA2000
Protocol	LTE-RRC
Technology	LTE
Direction	UE -> eNodeB
Interface	Uu
Signaling bearer / channel	SRB1 / UL-DCCH
Typical trigger	Triggered after CSFBParametersRequestCDMA2000 when the UE returns the requested cdma2000 parameters.
Main purpose	Supplies the requested cdma2000 fallback-related parameters so the network can continue the fallback branch.
Main specification	3GPP TS 36.331, 5.3.5, 6.2.2
Release added	Release 8
Procedures where used	cdma2000 CS fallback preparation

What is LTE RRC CSFB Parameters Response CDMA2000 in simple terms?

Uplink LTE RRC message used by the UE to return cdma2000 CS fallback parameters requested by the network.

Supplies the requested cdma2000 fallback-related parameters so the network can continue the fallback branch.

Why this message matters

CSFB Parameters Response CDMA2000 is the UE returning the cdma2000 fallback parameters the LTE network asked for.

Where this message appears in the call flow

cdma2000 CSFB parameter response

LTE flow showing CSFB Parameters Response CDMA2000 returned by the UE — The UE returns the requested cdma2000 parameters so the network can continue the fallback branch.

Call flow position: UE response carrying cdma2000 fallback parameters requested by the network.

Typical state: The parameter-exchange branch is closing and the network can continue fallback preparation.

Preconditions:

The network sent CSFBParametersRequestCDMA2000.

Next likely message: Later cdma2000 fallback continuation

cdma2000 fallback preparation continuation

LTE flow showing CSFB Parameters Response CDMA2000 before later fallback continuation — This response completes the parameter-exchange step that sits before the later cdma2000 fallback continuation.

Call flow position: UE response sent before the network moves from preparation into the next cdma2000 fallback step.

Typical state: The response completes the UE-side parameter return for the cdma2000 branch.

Preconditions:

The cdma2000 fallback preparation branch is active.

Next likely message: Fallback continuation or mobility command

Call flow position

Previous message(s): CSFBParametersRequestCDMA2000

Next message(s): Later cdma2000 CS fallback continuation

Message direction and transport

Sender and receiver: UE -> eNodeB

Interface: Uu

Domain: Access-side radio control with cdma2000 CSFB interworking

Signaling bearer: SRB1

Logical channel: UL-DCCH

Transport / encapsulation: Protected connected-mode LTE RRC signaling

Security context: Sent as protected connected-mode signaling.

Message Structure Overview

This message returns the UE-side cdma2000 fallback parameters requested by the network.

ASN.1 for LTE RRC CSFB Parameters Response CDMA2000

CSFBParametersResponseCDMA2000 ::= SEQUENCE {
  criticalExtensions CHOICE {
    c1 CHOICE {
      csfbParametersResponseCDMA2000-r8 SEQUENCE {},
      spare3 NULL,
      spare2 NULL,
      spare1 NULL
    },
    criticalExtensionsFuture SEQUENCE {}
  }
}

How to read this ASN.1

Read it together with the earlier request and the later fallback continuation.

LTE RRC CSFB Parameters Response CDMA2000 - Example Dump

UL-DCCH-Message
  message c1 : csfbParametersResponseCDMA2000-r8

How to read this dump

The message matters because it closes the parameter-exchange step, not because the wrapper itself is large.

Important Information Elements

IE	Required	Description
`criticalExtensions`	Yes	Carries the CSFBParametersResponseCDMA2000 branch and its parameter payload.

Detailed field explanation

`criticalExtensions`

Carries the CSFBParametersResponseCDMA2000 branch and its parameter payload.

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.

What to check in logs and traces

Confirm the response follows the request.
Check whether the branch continues into the expected cdma2000 fallback preparation step.

Common Issues and Troubleshooting

The network requests cdma2000 parameters but the fallback branch still does not progress.

Likely cause: The response may be missing, delayed, or not usable in the later branch.

What to inspect: Check whether CSFB Parameters Response CDMA2000 appears and what follows next.

Next step: Treat the issue as incomplete fallback preparation before assuming later mobility execution failure.

FAQ

What is CSFB Parameters Response CDMA2000 in LTE?

It is the uplink LTE RRC message the UE uses to return cdma2000 fallback-related parameters requested by the 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.