SIP 204 No Notification vs 422 Session Interval Too Small
SIP 204 (No Notification) is a 2xx Success response, while 422 (Session Interval Too Small) 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, 422 means that the request's Session-Expires value is too small. The Min-SE header in the response indicates the minimum acceptable session interval.
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 request's Session-Expires value is too small. The Min-SE header in the response indicates the minimum acceptable session interval.
When You See It
When using SIP session timers (RFC 4028) and the proposed session refresh interval is below the server's minimum.
How to Fix
Increase the Session-Expires value to at least the value indicated in the Min-SE header of the 422 response.
Key Differences
204 is a 2xx Success response, while 422 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 422: The request's Session-Expires value is too small. The Min-SE header in the response indicates the minimum acceptable session interval.
You encounter 204 when when subscribing to event packages that may not generate immediate notifications, such as dialog or presence packages.
You encounter 422 when when using SIP session timers (RFC 4028) and the proposed session refresh interval is below the server's minimum.
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 422 (Session Interval Too Small): Increase the Session-Expires value to at least the value indicated in the Min-SE header of the 422 response.