SIP 204 No Notification vs 408 Request Timeout
SIP 204 (No Notification) is a 2xx Success response, while 408 (Request Timeout) 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, 408 means that the server could not produce a response within a suitable time. The client may repeat the request without modifications at any later time.
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 server could not produce a response within a suitable time. The client may repeat the request without modifications at any later time.
When You See It
When the callee does not respond within the configured timeout (e.g., phone rings but is never answered, or the endpoint is unreachable).
How to Fix
Check if the callee's device is powered on and registered. Verify network connectivity. Consider adjusting the server's transaction timeout value.
Key Differences
204 is a 2xx Success response, while 408 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 408: The server could not produce a response within a suitable time. The client may repeat the request without modifications at any later time.
You encounter 204 when when subscribing to event packages that may not generate immediate notifications, such as dialog or presence packages.
You encounter 408 when when the callee does not respond within the configured timeout (e.g., phone rings but is never answered, or the endpoint is unreachable).
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 408 (Request Timeout): Check if the callee's device is powered on and registered. Verify network connectivity. Consider adjusting the server's transaction timeout value.