SIP 183 Session Progress vs 489 Bad Event
SIP 183 (Session Progress) is a 1xx Provisional response, while 489 (Bad Event) 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, 489 means that the server did not understand the event package specified in the Event header of a SUBSCRIBE request.
Mô tả
Used to convey information about the progress of the call that is not otherwise classified. Often carries early media (ringback tones, announcements) via SDP.
Khi bạn thấy mã này
During call setup, especially in PSTN interworking scenarios. The response may contain SDP for early media like custom ringback tones or IVR prompts.
Cách khắc phục
No fix needed — this is informational. If early media is not playing, check codec negotiation and SDP handling in your UA.
Mô tả
The server did not understand the event package specified in the Event header of a SUBSCRIBE request.
Khi bạn thấy mã này
When subscribing to an event package that the server does not support (e.g., dialog, presence, message-summary).
Cách khắc phục
Check which event packages the server supports (OPTIONS request) and use a supported event package name.
Sự khác biệt chính
183 is a 1xx Provisional response, while 489 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 489: The server did not understand the event package specified in the Event header of a SUBSCRIBE request.
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 489 when when subscribing to an event package that the server does not support (e.g., dialog, presence, message-summary).
Khi nào dùng cái nào
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 489 (Bad Event): Check which event packages the server supports (OPTIONS request) and use a supported event package name.