SIP 183 Session Progress vs 407 Proxy Authentication Required
SIP 183 (Session Progress) is a 1xx Provisional response, while 407 (Proxy Authentication Required) 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, 407 means that the client must first authenticate with the proxy. The proxy returns a Proxy-Authenticate header with a challenge.
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 client must first authenticate with the proxy. The proxy returns a Proxy-Authenticate header with a challenge.
Cuándo lo verás
When a SIP proxy requires authentication before forwarding the request. Similar to 401 but for proxy servers.
Cómo solucionarlo
Resend the request with a Proxy-Authorization header containing valid credentials for the proxy.
Diferencias clave
183 is a 1xx Provisional response, while 407 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 407: The client must first authenticate with the proxy. The proxy returns a Proxy-Authenticate header with a challenge.
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 407 when when a SIP proxy requires authentication before forwarding the request. Similar to 401 but for proxy servers.
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 407 (Proxy Authentication Required): Resend the request with a Proxy-Authorization header containing valid credentials for the proxy.