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.
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 client must first authenticate with the proxy. The proxy returns a Proxy-Authenticate header with a challenge.
Quand vous le voyez
When a SIP proxy requires authentication before forwarding the request. Similar to 401 but for proxy servers.
Comment résoudre
Resend the request with a Proxy-Authorization header containing valid credentials for the proxy.
Différences clés
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.
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 407 (Proxy Authentication Required): Resend the request with a Proxy-Authorization header containing valid credentials for the proxy.