What are SIP responses?
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- 301 Moved Permanently - The original Request URI is no longer valid, the new address is given in the Contact header.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 Unknown 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 service 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/doesn'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.