183
SIP
183 Session Progress
Used to convey information about the progress of the call that is not otherwise classified. Often carries early media (ringback tones, announcements) via SDP.
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During call setup, especially in PSTN interworking scenarios. The response may contain SDP for early media like custom ringback tones or IVR prompts.
Nasıl düzeltilir
No fix needed — this is informational. If early media is not playing, check codec negotiation and SDP handling in your UA.