SIP 183 Session Progress vs 485 Ambiguous
SIP 183 (Session Progress) is a 1xx Provisional response, while 485 (Ambiguous) 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, 485 means that the Request-URI was ambiguous. The response body may contain a list of possible unambiguous addresses.
설명
Used to convey information about the progress of the call that is not otherwise classified. Often carries early media (ringback tones, announcements) via SDP.
이 코드를 보게 되는 경우
During call setup, especially in PSTN interworking scenarios. The response may contain SDP for early media like custom ringback tones or IVR prompts.
해결 방법
No fix needed — this is informational. If early media is not playing, check codec negotiation and SDP handling in your UA.
설명
The Request-URI was ambiguous. The response body may contain a list of possible unambiguous addresses.
이 코드를 보게 되는 경우
When the destination address matches multiple users and the server cannot determine which one is intended.
해결 방법
Use a more specific SIP URI. Check the response body for a list of possible matches and select the correct one.
주요 차이점
183 is a 1xx Provisional response, while 485 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 485: The Request-URI was ambiguous. The response body may contain a list of possible unambiguous addresses.
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 485 when when the destination address matches multiple users and the server cannot determine which one is intended.
언제 어떤 것을 사용할지
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 485 (Ambiguous): Use a more specific SIP URI. Check the response body for a list of possible matches and select the correct one.