| Protocol | ims | Network | 5G and LTE |
|---|---|---|---|
| Spec | RFC 3261 / 3GPP TS 24.229 | Spec Section | SIP 404 Not Found target-resolution failure |
| Direction | IMS network -> UE | Message Type | SIP request-failure response |
| Full message name | IMS SIP 404 Not Found |
|---|---|
| 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 / Final request-failure response |
| Typical trigger | The dialed target, SIP URI, or service address is unknown. |
| Main purpose | Stops the request when the addressed identity or service target cannot be resolved. |
| Main specification | RFC 3261 / 3GPP TS 24.229, SIP 404 Not Found target-resolution failure |
| Release added | See specification history |
| Procedures where used | IMS Target Resolution Failure |
404 Not Found means the target user or service could not be found at the requested destination.
Stops the request when the addressed identity or service target cannot be resolved.
404 means the requested target was not found.
Previous message(s): IMS SIP INVITE, IMS SIP MESSAGE
Next message(s): Procedure stop or alternate routing
Security context: Uses the same protected IMS signaling path as the original request.
SIP/2.0 404 Not Found
Via:
From:
To:
Call-ID:
CSeq:
Content-Length: 0
This is SIP response syntax rather than ASN.1.
SIP/2.0 404 Not Found
Via: SIP/2.0/UDP ue.example.net;branch=z9hG4bK-inv1
From: <sip:alice@example.net>;tag=mo1
To: <sip:unknown@example.net>
Call-ID: call-001@example.net
CSeq: 1 INVITE
Content-Length: 0
| IE | Required | Description |
|---|---|---|
Status-Line | Yes | Shows the 404 failure code. |
Call-ID | Yes | Correlates the target-resolution failure with the request. |
Status-LineShows the 404 failure 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-IDCorrelates the target-resolution failure with the request.
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.
Likely cause: The target identity or service address does not exist at that destination.
What to inspect: Check the Request-URI, dialed identity, and any routing translation before the failure.
Next step: Verify the target address instead of focusing only on SIP transaction behavior.
It means the target user or service address could not be found for that request.
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.