| Protocol | ims | Network | 5G and LTE |
|---|---|---|---|
| Spec | RFC 3261 / 3GPP TS 24.229 | Spec Section | SIP 488 Not Acceptable Here failure response |
| Direction | IMS network -> UE | Message Type | SIP request-failure response |
| Full message name | IMS SIP 488 Not Acceptable Here |
|---|---|
| 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 media offer, codecs, SDP, or local session parameters are unacceptable at the reached target. |
| Main purpose | Rejects the current offer or session parameters at the reached destination. |
| Main specification | RFC 3261 / 3GPP TS 24.229, SIP 488 Not Acceptable Here failure response |
| Release added | See specification history |
| Procedures where used | IMS Media Negotiation Failure, VoNR SIP Failure, VoLTE SIP Failure |
488 Not Acceptable Here means the request reached the target, but the local media or session offer cannot be accepted there.
Rejects the current offer or session parameters at the reached destination.
488 means the local target could not accept the offered media or session parameters.
Previous message(s): IMS SIP INVITE, IMS SIP UPDATE
Next message(s): Procedure stop or revised offer
Security context: Uses the same protected IMS signaling path as the original request.
SIP/2.0 488 Not Acceptable Here
Via:
From:
To:
Call-ID:
CSeq:
Content-Length: 0
This is SIP response syntax rather than ASN.1.
SIP/2.0 488 Not Acceptable Here
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 488 failure code. |
Warning | Optional | Can add local explanation for the rejection. |
Status-LineShows the 488 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.
WarningCan add local explanation for the rejection.
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 local target could not accept the offered media or session parameters.
What to inspect: Compare the INVITE or UPDATE SDP with the target's supported media and policy.
Next step: Treat 488 as a media-offer or session-parameter problem first.
It means the reached destination could not accept the offered media or session parameters.
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.