SIP 204 No Notification vs 430 Flow Failed
SIP 204 (No Notification) is a 2xx Success response, while 430 (Flow Failed) is a 4xx Client Failure response. 204 indicates that the request was successful but the server has decided not to send a NOTIFY for this SUBSCRIBE request. In contrast, 430 means that the specific flow to a user agent has failed but other flows may succeed. Used with SIP outbound (RFC 5626).
Description
The request was successful but the server has decided not to send a NOTIFY for this SUBSCRIBE request.
When You See It
When subscribing to event packages that may not generate immediate notifications, such as dialog or presence packages.
How to Fix
No fix needed. The subscription was accepted but there is no state change to notify about yet.
Description
The specific flow to a user agent has failed but other flows may succeed. Used with SIP outbound (RFC 5626).
When You See It
When using SIP outbound connections and the specific TCP/TLS connection (flow) to the UA has been lost.
How to Fix
The proxy should attempt delivery via other registered flows. The UA should re-register to establish a new flow.
Key Differences
204 is a 2xx Success response, while 430 is a 4xx Client Failure response.
SIP 204: The request was successful but the server has decided not to send a NOTIFY for this SUBSCRIBE request.
SIP 430: The specific flow to a user agent has failed but other flows may succeed. Used with SIP outbound (RFC 5626).
You encounter 204 when when subscribing to event packages that may not generate immediate notifications, such as dialog or presence packages.
You encounter 430 when when using SIP outbound connections and the specific TCP/TLS connection (flow) to the UA has been lost.
When to Use Which
For 204 (No Notification): No fix needed. The subscription was accepted but there is no state change to notify about yet. For 430 (Flow Failed): The proxy should attempt delivery via other registered flows. The UA should re-register to establish a new flow.