| Protocol | ims | Network | 5G and LTE |
|---|---|---|---|
| Spec | RFC 3261 / 3GPP TS 24.229 | Spec Section | SIP 606 Not Acceptable global failure response |
| Direction | IMS network -> UE | Message Type | SIP global-failure response |
| Full message name | IMS SIP 606 Not Acceptable |
|---|---|
| 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 requested session or content constraints cannot be satisfied anywhere relevant to the request. |
| Main purpose | Stops alternate-location attempts by declaring the request globally unacceptable. |
| Main specification | RFC 3261 / 3GPP TS 24.229, SIP 606 Not Acceptable global failure response |
| Release added | See specification history |
| Procedures where used | IMS Global Capability Failure |
606 Not Acceptable means no acceptable target branch can satisfy the requested session or content constraints.
Stops alternate-location attempts by declaring the request globally unacceptable.
606 means the request is globally unacceptable, not just locally unacceptable on one branch.
Previous message(s): IMS SIP INVITE
Next message(s): Procedure stop
Security context: Uses the same protected IMS signaling path as the original request.
SIP/2.0 606 Not Acceptable
Via:
From:
To:
Call-ID:
CSeq:
Content-Length: 0
This is SIP response syntax rather than ASN.1.
SIP/2.0 606 Not Acceptable
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
| IE | Required | Description |
|---|---|---|
Status-Line | Yes | Shows the 606 global failure code. |
Accept | Optional | Can help explain which constraints were not satisfiable. |
Status-LineShows the 606 global 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.
AcceptCan help explain which constraints were not satisfiable.
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: The requested session constraints are globally unacceptable.
What to inspect: Compare the request constraints against all applicable service and media support.
Next step: Treat it as a wider capability mismatch than a single-branch failure.
It means no acceptable branch could satisfy the requested session or content constraints.
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.