SIP 183 Session Progress vs 436 Bad Identity-Info
SIP 183 (Session Progress) is a 1xx Provisional response, while 436 (Bad Identity-Info) 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, 436 means that the Identity-Info header contains a URI that the server cannot dereference to obtain the signing certificate.
Descripción
Used to convey information about the progress of the call that is not otherwise classified. Often carries early media (ringback tones, announcements) via SDP.
Cuándo lo verás
During call setup, especially in PSTN interworking scenarios. The response may contain SDP for early media like custom ringback tones or IVR prompts.
Cómo solucionarlo
No fix needed — this is informational. If early media is not playing, check codec negotiation and SDP handling in your UA.
Descripción
The Identity-Info header contains a URI that the server cannot dereference to obtain the signing certificate.
Cuándo lo verás
When the Identity-Info URI in the request points to an unreachable or invalid certificate location.
Cómo solucionarlo
Ensure the Identity-Info URI is reachable and points to a valid certificate. Check DNS resolution and TLS configuration.
Diferencias clave
183 is a 1xx Provisional response, while 436 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 436: The Identity-Info header contains a URI that the server cannot dereference to obtain the signing certificate.
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 436 when when the Identity-Info URI in the request points to an unreachable or invalid certificate location.
Cuándo usar cada uno
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 436 (Bad Identity-Info): Ensure the Identity-Info URI is reachable and points to a valid certificate. Check DNS resolution and TLS configuration.