- 2022-10-12 创建文档
100 Trying 说明caller正在呼叫，但还没联系上callee。
180 Ringing 说明callee已经被联系上,callee的铃正在响.收到这个信息后，等待200 OK
181 Call is being forwarded 说明call被重新路由到另外一个目的地
182 Queued 说明callee当前是不可获得的，但是对方不想直接拒绝呼叫，而是选择放在呼叫队列中
183 Session progress 用来警告caller频段(inband)错误。当从PSTN收到一个ISDN消息，SIP gateway 产生183 Session progress 。
2xx successful Responses¶
3xx Redirection Responses¶
300 Multiple choices 说明呼叫的地址被解析成多个地址，所有的地址都被提供出来，用户或用户代理可以从中选择联系哪个。
301 Moved permanently 说明指定地址的用户已经永远不可用，在头中已经用另外一个地址替换了.
302 Moved temporarily 说明指定地址的用户临时不可用，在头中已经用另外一个地址代替了.
305 Use proxy 说明caller必须用一个proxy来联系callee.
380 Alternative service 说明call不成功，但是可选择其他的服务
4xx Request Failure Responses¶
400 Bad Request 说明由于非法格式，请求不能被理解。
401 Unauthorized 说明请求需要用户认证。
402 Payment required 说明完成会话需要付费.
403 Forbidden 说明server已经收到并能理解请求但不提供服务。
404 Not Found 说明server有明确的信息在指定的域中用户不存在.
405 Method Not Allowed 说明请求中指定的方法是不被允许的。将返回一个允许的方法列表。
406 Not Acceptable 说明被请求的资源只对某些特殊的请求作出响应，对目前头(header)中指定的请求不接受.
407 Proxy authentication required 和401 Unauthorized response相似.但是，它说明client必须首先在proxy上认证自己。
408 Request timeout 说明在timeout时间过期前，server不能产生响应.
409 Conflict 说明由于和当前资源状态产生冲突，请求不能被处理。
410 Gone 说明请求资源在server上永远不可用，也没有转发的地址。
411 Length required 说明用户拒绝接受没有定义content长度的请求。
413 Request entity too large 说明server拒绝处理请求，因为它太大，超过了server能处理的大小。
414 Request-URI too long 说明server拒绝处理请求，因为请求的URI太长，server不能解释它。
415 Unsupported media 说明server拒绝处理请求，因为body格式不被目的终端支持
420 Bad extension 说明server不能理解在header中指出的扩展协议。
480 Temporarily unavailable 说明callee已经被联系上，但是暂时不可用。
481 Call leg/transaction does not exist 说明server正在忽略请求，由于它是一个没有匹配legID的BYE或 者是一个没有匹配事务的CANCEL。
482 Loop detected 说明server收到了一个包含它自己路径的请求.
483 Too many hops 说明server收到了一个请求，它需要的hop数超过了在header中允许的最大hop数.
484 Address incomplete 说明server收到一个地址不完整的请求.
485 Ambiguous 说明server收到一个请求，其中callee的地址是不明确的，也没有可能备用的地址供选择。
486 Busy here 说明callee已经被联系上，但是它们的系统不能承受额外的call.
5xx Server Failure Responses¶
500 Server internal error 说明server或gateway发生意外错误从而不能处理请求.
501 Not implemented 说明server或gateway不支持完成请求所需的功能.
502 Bad gateway 说明server或gateway从下游server收到一个非法响应.
503 Service unavailable 说明由于超负载或维护问题，server或gateway不能处理请求.
504 Gateway timeout 说明server或gateway没有从另外一个server(如location server)收到一个及时的响应.
505 Version not supported 说明server或gateway不支持在请求中用到的SIP版本。
6xx Global Responses¶
600 Busy everywhere 说明callee已经被联系上，但是处于忙状态中，在这个时间不能接受call。
603 Decline 说明callee已经被联系上，但是不能或不想加入call。
604 Does not exist anywhere 说明server有正式的信息说明callee不存在于网络中。
606 Not acceptable 说明callee已经被联系上，但是session描述的某些方面不被接受。
SIP responses are the codes used by Session Initiation Protocol for communication. We have put together a list of all the SIP responses known.
1xx = Informational SIP responses¶
100 Trying - Extended search is being performed so a forking proxy must send a 100 Trying response.
180 Ringing - The Destination User Agent has received the INVITE message and is alerting the user of call.
181 Call Is Being Forwarded - Optional, send by Server to indicate a call is being forwarded.
182 Queued - Destination was temporarily unavailable, the server has queued the call until the destination is available.
183 Session Progress - This response may be used to send extra information for a call which is still being set up.
199 Early Dialog Terminated - Send by the User Agent Server to indicate that an early dialogue has been terminated.
2xx = Success responses¶
200 OK - Shows that the request was successful.
202 Accepted - Indicates that the request has been accepted for processing, mainly used for referrals.
204 No Notification - Indicates that the request was successful but no response will be received.
3xx = Redirection responses¶
300 Multiple Choices - The address resolved to one of several options for the user or client to choose between.
301 Moved Permanently - The original Request URI is no longer valid, the new address is given in the Contact header.
302 Moved Temporarily - The client should try at the address in the Contact field.
305 Use Proxy - The Contact field details a proxy that must be used to access the requested destination.
380 Alternative Service - The call failed, but alternatives are detailed in the message body.
4xx = Request failures¶
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 fulfil 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 any more.
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 - 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.
5xx = Server errors¶
500 Server Internal Error - The server could not fulfill the request due to some unexpected condition.
501 Not Implemented - The SIP request method is not implemented here.
502 Bad Gateway - The server, received an invalid response from a downstream server while trying to fulfill a request.
503 Service Unavailable - The server is in maintenance or is temporarily overloaded and cannot process the request.
504 Server Time-out - The server tried to access another server while trying to process a request, no timely response.
505 Version Not Supported - The SIP protocol version in the request is not supported by the server.
513 Message Too Large - The request message length is longer than the server can process.
555 Push Notification Service Not Supported - The server does not support the push notification serviced specified in the pn-provider SIP URI parameter.
580 Precondition Failure - The server is unable or unwilling to meet some constraints specified in the offer.
6xx = Global failures¶
600 Busy Everywhere - All possible destinations are busy.
603 Decline - Destination cannot/doen't wish to participate in the call, no alternative destinations.
604 Does Not Exist Anywhere - The server has authoritative information that the requested user does not exist anywhere.
606 Not Acceptable - The user's agent was contacted successfully but some aspects of the session description were not acceptable.
607 Unwanted - The called party did not want his call from the calling party. Future attempts from the calling party are likely to be similarly rejected.