SIP 204 No Notification vs 438 Invalid Identity Header
SIP 204 (No Notification) is a 2xx Success response, while 438 (Invalid Identity Header) 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, 438 means that the server obtained the certificate from the Identity-Info header but the signature in the Identity header is invalid.
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 obtained the certificate from the Identity-Info header but the signature in the Identity header is invalid.
When You See It
When the cryptographic signature in the Identity header does not match the message content, indicating possible tampering.
How to Fix
Regenerate the Identity header with a correct signature. Ensure no intermediary is modifying signed headers after signing.
Key Differences
204 is a 2xx Success response, while 438 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 438: The server obtained the certificate from the Identity-Info header but the signature in the Identity header is invalid.
You encounter 204 when when subscribing to event packages that may not generate immediate notifications, such as dialog or presence packages.
You encounter 438 when when the cryptographic signature in the Identity header does not match the message content, indicating possible tampering.
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 438 (Invalid Identity Header): Regenerate the Identity header with a correct signature. Ensure no intermediary is modifying signed headers after signing.