SIP 183 Session Progress vs 438 Invalid Identity Header
SIP 183 (Session Progress) is a 1xx Provisional response, while 438 (Invalid Identity Header) is a 4xx Client Failure response. 183 indicates that used to convey information about the progress of the call that is not otherwise classified. Often carries early media (ringback tones, announcements) via SDP. 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
Used to convey information about the progress of the call that is not otherwise classified. Often carries early media (ringback tones, announcements) via SDP.
Quand vous le voyez
During call setup, especially in PSTN interworking scenarios. The response may contain SDP for early media like custom ringback tones or IVR prompts.
Comment résoudre
No fix needed — this is informational. If early media is not playing, check codec negotiation and SDP handling in your UA.
Description
The server obtained the certificate from the Identity-Info header but the signature in the Identity header is invalid.
Quand vous le voyez
When the cryptographic signature in the Identity header does not match the message content, indicating possible tampering.
Comment résoudre
Regenerate the Identity header with a correct signature. Ensure no intermediary is modifying signed headers after signing.
Différences clés
183 is a 1xx Provisional response, while 438 is a 4xx Client Failure response.
SIP 183: Used to convey information about the progress of the call that is not otherwise classified. Often carries early media (ringback tones, announcements) via SDP.
SIP 438: The server obtained the certificate from the Identity-Info header but the signature in the Identity header is invalid.
You encounter 183 when during call setup, especially in PSTN interworking scenarios. The response may contain SDP for early media like custom ringback tones or IVR prompts.
You encounter 438 when when the cryptographic signature in the Identity header does not match the message content, indicating possible tampering.
Quand utiliser lequel
For 183 (Session Progress): No fix needed — this is informational. If early media is not playing, check codec negotiation and SDP handling in your UA. For 438 (Invalid Identity Header): Regenerate the Identity header with a correct signature. Ensure no intermediary is modifying signed headers after signing.