SIP 183 Session Progress vs 423 Interval Too Brief
SIP 183 (Session Progress) is a 1xx Provisional response, while 423 (Interval Too Brief) 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, 423 means that the expiration time in the request is too short. The response contains a Min-Expires header indicating the minimum allowed value.
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 expiration time in the request is too short. The response contains a Min-Expires header indicating the minimum allowed value.
Khi bạn thấy mã này
When a REGISTER or SUBSCRIBE request has an Expires value that is below the server's minimum. Common with aggressive keep-alive timers.
Cách khắc phục
Increase the Expires header value to at least the Min-Expires value from the response.
Sự khác biệt chính
183 is a 1xx Provisional response, while 423 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 423: The expiration time in the request is too short. The response contains a Min-Expires header indicating the minimum allowed value.
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 423 when when a REGISTER or SUBSCRIBE request has an Expires value that is below the server's minimum. Common with aggressive keep-alive timers.
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 423 (Interval Too Brief): Increase the Expires header value to at least the Min-Expires value from the response.