| Code
| Name
| Description
|
| 400 | Bad Request | The request could not be understood due to malformed syntax.
|
| 401 | Unauthorized | The request requires user authentication. This response is issued by UASs and registrars.
|
| 402 | Payment Required | (Reserved for future use).
|
| 403 | Forbidden | The server understood the request but is refusing to fulfill it.
|
| 404 | Not Found | The server has definitive information that the user does not exist at the (User not found).
|
| 405 | Method Not Allowed | The method specified in the Request-Line is understood, but not allowed.
|
| 406 | Not Acceptable | The resource is only capable of generating responses with unacceptable content.
|
| 407 | Proxy Authentication Required | The request requires user authentication.
|
| 408 | Request Timeout | Couldn’t find the user in time.
|
| 409 | Conflict | User already registered (deprecated)
|
| 410 | Gone | The user existed once but is not available here anymore.
|
| 411 | Length Required | The server will not accept the request without a valid content length (deprecated).
|
| 412 | Conditional Request Failed | The given precondition has not been met.
|
| 413 | Request Entity Too Large | Request body too large.
|
| 414 | Request URI Too Long | Server refuses to service the request, the Req-URI is longer than the server can interpret.
|
| 415 | Unsupported Media Type | Request body is in a non-supported format.
|
| 416 | Unsupported URI Scheme | Request-URI is unknown to the server.
|
| 417 | Uknown Resource-Priority | There was a resource-priority option tag, but no Resource-Priority header.
|
| 420 | Bad Extension | Bad SIP Protocol Extension used, not understood by the server.
|
| 421 | Extension Required | The server needs a specific extension not listed in the Supported header.
|
| 422 | Session Interval Too Small | The request contains a Session-Expires header field with a duration below the minimum.
|
| 423 | Interval Too Brief | The expiration time of the resource is too short.
|
| 424 | Bad Location Information | The request’s location content was malformed or otherwise unsatisfactory.
|
| 428 | Use Identity Header | The server policy requires an Identity header, and one has not been provided.
|
| 429 | Provide Referrer Identity | The server did not receive a valid Referred-By token on the request.
|
| 430 | Flow Failed | A specific flow to a user agent has failed, although other flows may succeed.
|
| 433 | Anonymity Disallowed | The request has been rejected because it was anonymous.
|
| 436 | Bad Identity-Info | The request has an Identity-Info header and the URI scheme contained cannot be de-referenced.
|
| 437 | Unsupported Certificate | The server was unable to validate a certificate for the domain that signed the request.
|
| 438 | Invalid Identity Header | Server obtained a valid certificate used to sign a request, was unable to verify the signature.
|
| 439 | First Hop Lacks Outbound Support | The first outbound proxy doesn’t support the “outbound” feature.
|
| 440 | Max-Breadth Exceeded | If a SIP proxy determined a response context had insufficient Incoming Max-Breadth to carry out a desired parallel fork, and the proxy is unwilling/unable to compensate by forking serially or sending a redirect, that proxy MUST return a 440 response. A client receiving a 440 response can infer that its request did not reach all possible destinations.
|
| 469 | Bad Info Package | If a SIP UA receives an INFO request associated with an Info Package that the UA has not indicated willingness to receive, the UA MUST send a 469 response, which contains a Recv-Info header field with Info Packages for which UA is willing to receive INFO requests.
|
| 470 | Consent Needed | The source of the request did not have the permission of the recipient to make such a request.
|
| 480 | Temporarily Unavailable | Callee currently unavailable.
|
| 481 | Call/Transaction Does Not Exist | Server received a request that does not match any dialogue or transaction.
|
| 482 | Loop Detected | Server has detected a loop.
|
| 483 | Too Many Hops | Max-Forwards header has reached the value ‘0’.
|
| 484 | Address Incomplete | Request-URI incomplete.
|
| 485 | Ambiguous | Request-URI is ambiguous.
|
| 486 | Busy Here | Callee is busy.
|
| 487 | Request Terminated | Request has terminated by bye or cancel.
|
| 488 | Not Acceptable Here | Some aspects of the session description of the Request-URI are not acceptable.
|
| 489 | Bad Event | The server did not understand an event package specified in an Event header field.
|
| 491 | Request Pending | Server has some pending request from the same dialogue.
|
| 493 | Undecipherable | UndecipherableRequest contains an encrypted MIME body, which recipient can not decrypt.
|
| 494 | Security Agreement Required | The server has received a request that requires a negotiated security mechanism.
|
