SIP
513 Message Too Large
The server was unable to process the request since the entire SIP message (not just the body) exceeded the size limit.
Когда вы видите этот код
When the total SIP message (headers + body) is too large. Different from 413 which refers only to the body.
Как исправить
Reduce the message size by removing unnecessary headers or reducing the SDP size. Consider using UDP-compatible message sizes (< 1300 bytes).