SIP 183 Session Progress vs 380 Alternative Service
SIP 183 (Session Progress) is a 1xx Provisional response, while 380 (Alternative Service) is a 3xx Redirection 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, 380 means that the call was not successful but alternative services are possible. The response body contains a description of alternative services.
描述
Used to convey information about the progress of the call that is not otherwise classified. Often carries early media (ringback tones, announcements) via SDP.
何时出现
During call setup, especially in PSTN interworking scenarios. The response may contain SDP for early media like custom ringback tones or IVR prompts.
如何修复
No fix needed — this is informational. If early media is not playing, check codec negotiation and SDP handling in your UA.
描述
The call was not successful but alternative services are possible. The response body contains a description of alternative services.
何时出现
Rarely seen in practice. Indicates that the request cannot be fulfilled as-is but the user may be reached via an alternative method.
如何修复
Check the response body for alternative service descriptions and attempt to reach the user through those channels.
主要区别
183 is a 1xx Provisional response, while 380 is a 3xx Redirection 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 380: The call was not successful but alternative services are possible. The response body contains a description of alternative services.
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 380 when rarely seen in practice. Indicates that the request cannot be fulfilled as-is but the user may be reached via an alternative method.
何时使用哪个
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 380 (Alternative Service): Check the response body for alternative service descriptions and attempt to reach the user through those channels.