| Protocol | ims | Network | 5G and LTE |
|---|---|---|---|
| Spec | RFC 3261 / 3GPP TS 24.229 | Spec Section | SIP 504 Server Time-out failure response |
| Direction | IMS network -> UE | Message Type | SIP server-failure response |
| Full message name | IMS SIP 504 Server Time-out |
|---|---|
| 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 / Server-failure response |
| Typical trigger | A downstream server or service element did not answer in time. |
| Main purpose | Shows that the current server waited for another downstream element and the chain timed out. |
| Main specification | RFC 3261 / 3GPP TS 24.229, SIP 504 Server Time-out failure response |
| Release added | See specification history |
| Procedures where used | IMS Inter-Server Timeout |
504 Server Time-out means a server did not get a timely answer from another server while handling the request.
Shows that the current server waited for another downstream element and the chain timed out.
504 means one server timed out while waiting for another server.
Previous message(s): IMS SIP INVITE, IMS SIP REGISTER
Next message(s): Retried request or alternate routing
Security context: Uses the same protected IMS signaling path as the original request.
SIP/2.0 504 Server Time-out
Via:
From:
To:
Call-ID:
CSeq:
Content-Length: 0
This is SIP response syntax rather than ASN.1.
SIP/2.0 504 Server Time-out
Via: SIP/2.0/UDP ue.example.net;branch=z9hG4bK-reg1
From: <sip:alice@example.net>;tag=reg1
To: <sip:alice@example.net>;tag=pcscf1
Call-ID: reg-001@example.net
CSeq: 1 REGISTER
Content-Length: 0
| IE | Required | Description |
|---|---|---|
Status-Line | Yes | Shows the 504 failure code. |
Call-ID | Yes | Correlates the timeout with the affected transaction. |
Status-LineShows the 504 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 timeout with the affected transaction.
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: Another server in the path did not answer in time.
What to inspect: Check which server generated 504 and what downstream dependency it was waiting on.
Next step: Treat it as a chain timeout rather than a pure target or media issue.
It means a server could not get a timely response from another server while processing the 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.