IMS 5G AND LTE IMS network -> UE RFC 8688 / 3GPP TS 24.229

IMS SIP 608 Rejected

608 Rejected means the request was rejected without exposing the more specific target-state reason.

Message Fact Sheet

Protocol	ims	Network	5G and LTE
Spec	RFC 8688 / 3GPP TS 24.229	Spec Section	SIP 608 Rejected response and identity-protection-aware rejection
Direction	IMS network -> UE	Message Type	SIP global-failure response

Full message name	IMS SIP 608 Rejected
Protocol	IMS
Technology	5G and LTE
Common deployment	VoNR and VoLTE
Direction	IMS network -> UE
Interface	Gm with onward IMS routing
Signaling bearer / channel	IMS SIP signaling / Global failure response
Typical trigger	The service intentionally rejects the request while avoiding disclosure of the exact destination state.
Main purpose	Provides a privacy-preserving or policy-driven rejection result instead of a more revealing detailed failure.
Main specification	RFC 8688 / 3GPP TS 24.229, SIP 608 Rejected response and identity-protection-aware rejection
Release added	See specification history
Procedures where used	IMS Privacy-Aware Rejection

What is IMS SIP 608 Rejected in simple terms?

608 Rejected means the request was rejected without exposing the more specific target-state reason.

Provides a privacy-preserving or policy-driven rejection result instead of a more revealing detailed failure.

Why this message matters

608 means the request was rejected, but the service is not exposing a more specific reason.

Where this message appears in the call flow

IMS Privacy-Aware Rejection

Call flow position

Previous message(s): IMS SIP INVITE

Next message(s): Procedure stop

Message direction and transport

Sender and receiver: IMS network -> UE

Interface: Gm with onward IMS routing

Domain: IMS privacy-aware rejection handling

Signaling bearer: IMS SIP signaling

Logical channel: Global failure response

Transport / encapsulation: SIP over UDP, TCP, or TLS

Security context: Uses the same protected IMS signaling path as the original request.

Message Structure Overview

608 is a rejection result that intentionally reveals less than more specific failure codes.

ASN.1 Message Syntax for IMS SIP 608 Rejected

SIP/2.0 608 Rejected
Via:
From:
To:
Call-ID:
CSeq:
Content-Length: 0

How to read this message syntax

This is SIP response syntax rather than ASN.1.

IMS SIP 608 Rejected - Example Dump

SIP/2.0 608 Rejected
Via: SIP/2.0/UDP ue.example.net;branch=z9hG4bK-inv1
From: <sip:alice@example.net>;tag=mo1
To: <sip:bob@example.net>;tag=term1
Call-ID: call-001@example.net
CSeq: 1 INVITE
Content-Length: 0

Important Information Elements

IE	Required	Description
`Status-Line`	Yes	Shows the 608 rejection code.
`Call-ID`	Yes	Correlates the privacy-aware rejection with the request.

Detailed field explanation

`Status-Line`

Shows the 608 rejection code.

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.

`Call-ID`

Correlates the privacy-aware rejection with the request.

Presence: Required

Common Issues and Troubleshooting

The request is rejected, but the response avoids giving a more specific reason.

Likely cause: The service is using a privacy-preserving or policy-driven rejection result.

What to inspect: Check service policy and whether detailed target-state disclosure is intentionally suppressed.

Next step: Do not assume the same meaning as 603, 404, or 486 without wider context.

FAQ

What does 608 Rejected mean in IMS?

It means the request was rejected, often with less disclosure about the exact destination state or reason.

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.