SIP status codes
SIP status codes , inexactly also called SIP error codes or SIP responses, denote the possible responses to a SIP request . The Session Initiation Protocol (SIP) for setting up, controlling and terminating a communication session (mostly IP telephony ) is based on the Hypertext Transfer Protocol . The subscriber devices send each other requests ( English requests ) and answer them using response codes ( English responses ), which are based on the HTTP status codes .
List of SIP status codes
1xx - Provisional
Preliminary information that the server is still performing further actions and therefore cannot yet send a final response.
| code | message | meaning |
|---|---|---|
| 100 | Trying | Attempting to transfer the call . |
| 180 | Ringing | An attempt is made to ring the called party . |
| 181 | Call Is Being Forwarded | The call is transferred. |
| 182 | Queued | The call is on hold . |
| 183 | Session progress | The connection is established. |
| 199 | Early Dialog Terminated | The dialog was ended while the connection was being established. |
2xx - Successful
The request was successful.
| code | message | meaning |
|---|---|---|
| 200 | OK | The request was processed successfully and the result of the request is transmitted in the response. |
| 202 | Accepted | The request was accepted, but will be executed at a later time. |
| 204 | No notification | The request was carried out successfully, but the corresponding response is deliberately not sent. |
3xx - redirection
These messages inform about a new contact address of the called party or about other services that enable the connection to be successfully established.
| code | message | meaning |
|---|---|---|
| 300 | Multiple Choices | There is no unique destination address for the remote station. |
| 301 | Moved permanently | The called party can be reached permanently elsewhere. |
| 302 | Moved Temporarily | The called party can be reached temporarily elsewhere. |
| 305 | Use proxy | The specified proxy must be used. |
| 380 | Alternative service | The call was unsuccessful, but alternative services are available. |
4xx - Request Failures
Request failures are negative feedback. The previous message could not be processed.
| code | message | meaning |
|---|---|---|
| 400 | Bad request | The SIP request is incorrect. |
| 401 | Unauthorized | The authorization is incorrect. |
| 402 | Payment Required | Not yet defined; intended for "insufficient credit available". |
| 403 | Forbidden | The request was inadmissible. |
| 404 | Not Found | The remote station was not found or does not exist. |
| 405 | Method Not Allowed | The method of the request (for example SUBSCRIBE or NOTIFY) is not permitted. |
| 406 | Not acceptable | The options of the call are not allowed. |
| 407 | Proxy Authentication Required | The proxy needs authorization. |
| 408 | Request timeout | Timeout - The remote station does not respond within a reasonable time. |
| 410 | Gone | The desired participant can no longer be reached at the specified address. |
| 412 | Conditional Request Failed | The prerequisites for processing the request could not be established because a request required for this failed. |
| 413 | Request Entity Too Large | The message content is too big. |
| 414 | Request URI Too Long | The SIP address ( URI ) of the request is too long. |
| 415 | Unsupported Media Type | The codec is not supported. |
| 416 | Unsupported URI Scheme | The SIP address is incorrect. |
| 417 | Unknown resource priority | The request should be treated with a certain priority, but the server does not understand the information. |
| 420 | Bad Extension | The server does not understand a protocol extension. |
| 421 | Extension Required | The server needs a protocol extension. |
| 422 | Session Interval Too Small | The Session Expires value is too low for the server. |
| 423 | Interval Too Brief | The value of the desired processing time is too short. |
| 428 | Use Identity Header | The identity header is missing. |
| 429 | Provide Referrer Identity | It is not a valid Referred-By - tokens given. |
| 430 | Flow Failed | The selected route failed (proxy-internal, endpoints should treat the response like Code 400). |
| 433 | Anonymity Disallowed | The server refuses to process anonymous requests. |
| 436 | Bad identity info | The SIP address contained in the identity header is invalid, cannot be reached or is not supported. |
| 437 | Unsupported Certificate | The verifier can not check the certificate in the identity header . |
| 438 | Invalid Identity Header | The certificate in the identity header is invalid. |
| 439 | First Hop Lacks Outbound Support | The registrar supports outbound features, but the proxy used does not. |
| 440 | Max-Breadth Exceeded | Concurrent forks can no longer be derived from the request. |
| 469 | Bad Info Package | Unsuitable info package - transmission error, send again. |
| 470 | Consent Needed | The server has no access rights to at least one of the specified SIP addresses. |
| 480 | Temporarily unavailable | The called subscriber is currently unavailable. |
| 481 | Call / Transaction Does Not Exist | This connection does not exist (anymore). |
| 482 | Loop Detected | A forwarding loop was detected. |
| 483 | Too many hops | Too many redirect steps were encountered. |
| 484 | Address Incomplete | The SIP address is incomplete. |
| 485 | Ambiguous | The SIP address cannot be clearly resolved. |
| 486 | Busy here | The called subscriber is busy. |
| 487 | Request terminated | The call attempt was canceled. |
| 488 | Not Acceptable Here | Invalid call attempt. |
| 489 | Bad event | The server does not know the specified event. |
| 491 | Request pending | A request for the same dialog is still being processed. |
| 493 | Undecipherable | The request contains an encrypted MIME body that the recipient cannot decrypt. |
| 494 | Security Agreement Required | The request requires a security agreement , but does not contain any security mechanism supported by the server. |
5xx - Server Failures
A server involved in the transmission could not process a message.
| code | message | meaning |
|---|---|---|
| 500 | Server internal error | Internal server error. |
| 501 | Not implemented | The server does not support the SIP request. |
| 502 | Bad gateway | The gateway in the SIP request is faulty. |
| 503 | Service Unavailable | The server's SIP service is temporarily unavailable. |
| 504 | Server time-out | The server cannot reach another server in a reasonable time. |
| 505 | Version Not Supported | The server does not support the SIP protocol version. |
| 513 | Message Too Large | The SIP message is too large for UDP ; TCP must be used. |
| 580 | Precondition Failure | The server cannot or does not want to meet the requirements for processing the request. |
6xx - Global Failures
General errors: The server was contacted successfully, but the transaction does not take place.
| code | message | meaning |
|---|---|---|
| 600 | Busy Everywhere | All terminals of the called subscriber are busy. |
| 603 | Declined | The called subscriber refused the call attempt. |
| 604 | Does not exist anywhere | The called subscriber no longer exists. |
| 606 | Not acceptable | The device of the called subscriber rejects the SIP request as inadmissible. |
7xx - error codes of the SIP stack
| code | message | meaning |
|---|---|---|
| 701 | Party hangs up | The called party hung up |
Individual evidence
- ↑ RFC 3261 , supplemented by further RFCs, broken down by the IANA
- ↑ RFC 6228 Session Initiation Protocol (SIP) Response Code for Indication of Terminated Dialog