SIP 183 Session Progress vs 513 Message Too Large
SIP 183 (Session Progress) is a 1xx Provisional response, while 513 (Message Too Large) is a 5xx Server 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, 513 means that the server was unable to process the request since the entire SIP message (not just the body) exceeded the size limit.
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 was unable to process the request since the entire SIP message (not just the body) exceeded the size limit.
When You See It
When the total SIP message (headers + body) is too large. Different from 413 which refers only to the body.
How to Fix
Reduce the message size by removing unnecessary headers or reducing the SDP size. Consider using UDP-compatible message sizes (< 1300 bytes).
Key Differences
183 is a 1xx Provisional response, while 513 is a 5xx Server 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 513: The server was unable to process the request since the entire SIP message (not just the body) exceeded the size limit.
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 513 when when the total SIP message (headers + body) is too large. Different from 413 which refers only to the body.
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 513 (Message Too Large): Reduce the message size by removing unnecessary headers or reducing the SDP size. Consider using UDP-compatible message sizes (< 1300 bytes).