SIP 183 Session Progress vs 404 Not Found
SIP 183 (Session Progress) is a 1xx Provisional response, while 404 (Not Found) 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, 404 means that the user specified in the Request-URI does not exist at the domain. The server has authoritative information that the user does not exist.
الوصف
Used to convey information about the progress of the call that is not otherwise classified. Often carries early media (ringback tones, announcements) via SDP.
متى تراه
During call setup, especially in PSTN interworking scenarios. The response may contain SDP for early media like custom ringback tones or IVR prompts.
كيفية الإصلاح
No fix needed — this is informational. If early media is not playing, check codec negotiation and SDP handling in your UA.
الوصف
The user specified in the Request-URI does not exist at the domain. The server has authoritative information that the user does not exist.
متى تراه
When calling a number or SIP address that does not exist on the server. Different from 480 (user exists but is temporarily unavailable).
كيفية الإصلاح
Verify the SIP URI or phone number. Check if the user is registered on the correct domain. Ensure the domain is correct.
الفروق الرئيسية
183 is a 1xx Provisional response, while 404 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 404: The user specified in the Request-URI does not exist at the domain. The server has authoritative information that the user does not exist.
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 404 when when calling a number or SIP address that does not exist on the server. Different from 480 (user exists but is temporarily unavailable).
متى تستخدم أيًا منهما
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 404 (Not Found): Verify the SIP URI or phone number. Check if the user is registered on the correct domain. Ensure the domain is correct.