SIP 183 Session Progress vs 413 Request Entity Too Large
SIP 183 (Session Progress) is a 1xx Provisional response, while 413 (Request Entity Too Large) 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, 413 means that the server is refusing to process the request because the message body is larger than the server is willing to accept.
Description
Used to convey information about the progress of the call that is not otherwise classified. Often carries early media (ringback tones, announcements) via SDP.
When You See It
During call setup, especially in PSTN interworking scenarios. The response may contain SDP for early media like custom ringback tones or IVR prompts.
How to Fix
No fix needed — this is informational. If early media is not playing, check codec negotiation and SDP handling in your UA.
Description
The server is refusing to process the request because the message body is larger than the server is willing to accept.
When You See It
When sending a SIP message with a body (SDP, XML, etc.) that exceeds the server's size limit.
How to Fix
Reduce the size of the message body. For SDP, minimize codec offers or remove unnecessary attributes.
Key Differences
183 is a 1xx Provisional response, while 413 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 413: The server is refusing to process the request because the message body is larger than the server is willing to accept.
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 413 when when sending a SIP message with a body (SDP, XML, etc.) that exceeds the server's size limit.
When to Use Which
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 413 (Request Entity Too Large): Reduce the size of the message body. For SDP, minimize codec offers or remove unnecessary attributes.