SIP Responses

Identifying Error Codes the Easy Way


SIP Responses

Identify the SIP Errors on your PBX Phone
Note: For finding the explanation on the error code displayed on your phone, type the code in the search area below for quick access

Code Response Explanation
100 TryingProvisionalExtended search being performed may take a significant time so a forking proxy must send a 100 Trying response.
180 RingingProvisional Destination user agent received INVITE, and is alerting user of call.
181 Call is Being ForwardedProvisional Servers can optionally send this response to indicate a call is being forwarded.
182 QueuedProvisionalIndicates that the destination was temporarily unavailable, so the server has queued the call until the destination is available. A server may send multiple 182 responses to update progress of the queue.
183 Session ProgressProvisionalThis response may be used to send extra information for a call which is still being set up.
199 Early Dialog TerminatedProvisionalCan be used by User Agent Server to indicate to upstream SIP entities (including the User Agent Client (UAC)) that an early dialog has been terminated.
200 OKSuccessful Indicates the request was successful.
202 AcceptedSuccessful Indicates that the request has been accepted for processing, but the processing has not been completed.
204 No NotificationSuccessful Indicates the request was successful, but the corresponding response will not be received.
300 Multiple ChoicesRedirectionThe address resolved to one of several options for the user or client to choose between, which are listed in the message body or the message's Contact fields.
301 Moved PermanentlyRedirectionThe original Request-URI is no longer valid, the new address is given in the Contact header field, and the client should update any records of the original Request-URI with the new value.
302 Moved TemporarilyRedirectionThe client should try at the address in the Contact field. If an Expires field is present, the client may cache the result for that period of time.
305 Use ProxyRedirectionThe Contact field details a proxy that must be used to access the requested destination.
380 Alternative ServiceRedirectionThe call failed, but alternatives are detailed in the message body.
400 Bad RequestClient FailureThe request could not be understood due to malformed syntax.
401 UnauthorizedClient FailureThe request requires user authentication. This response is issued by UASs and registrars.
402 Payment RequiredClient FailureReserved for future use.
403 ForbiddenClient FailureThe server understood the request, but is refusing to fulfill it. Sometimes (but not always) this means the call has been rejected by the receiver.
404 Not FoundClient FailureThe server has definitive information that the user does not exist at the domain specified in the Request-URI. This status is also returned if the domain in the Request-URI does not match any of the domains handled by the recipient of the request.
405 Method Not AllowedClient FailureThe method specified in the Request-Line is understood, but not allowed for the address identified by the Request-URI.
406 Not AcceptableClient FailureThe resource identified by the request is only capable of generating response entities that have content characteristics but not acceptable according to the Accept header field sent in the request.
407 Proxy Authentication RequiredClient FailureThe request requires user authentication. This response is issued by proxys.
408 Request TimeoutClient FailureCouldn't find the user in time. The server could not produce a response within a suitable amount of time, for example, if it could not determine the location of the user in time. The client MAY repeat the request without modifications at any later time.
409 ConflictClient FailureUser already registered.
410 GoneClient FailureThe user existed once, but is not available here any more.
411 Length RequiredClient FailureThe server will not accept the request without a valid Content-Length.
412 Conditional Request FailedClient FailureThe given precondition has not been met.
413 Request Entity Too LargeClient FailureRequest body too large.
414 Request-URI Too LongClient FailureThe server is refusing to service the request because the Request-URI is longer than the server is willing to interpret.
415 Unsupported Media TypeClient FailureRequest body in a format not supported.
416 Unsupported URI SchemeClient FailureRequest-URI is unknown to the server.
417 Unknown Resource-PriorityClient FailureThere was a resource-priority option tag, but no Resource-Priority header.
420 Bad ExtensionClient FailureBad SIP Protocol Extension used, not understood by the server.
421 Extension RequiredClient FailureThe server needs a specific extension not listed in the Supported header.
422 Session Interval Too SmallClient FailureThe received request contains a Session-Expires header field with a duration below the minimum timer.
423 Interval Too BriefClient FailureExpiration time of the resource is too short.
424 Bad Location InformationClient FailureThe request's location content was malformed or otherwise unsatisfactory.
428 Use Identity HeaderClient FailureThe server policy requires an Identity header, and one has not been provided.
429 Provide Referrer IdentityClient FailureThe server did not receive a valid Referred-By token on the request.
430 Flow FailedClient FailureA specific flow to a user agent has failed, although other flows may succeed. This response is intended for use between proxy devices, and should not be seen by an endpoint (and if it is seen by one, should be treated as a 400 Bad Request response).
433 Anonymity DisallowedClient FailureThe request has been rejected because it was anonymous.
436 Bad Identity-InfoClient FailureThe request has an Identity-Info header, and the URI scheme in that header cannot be dereferenced.
437 Unsupported CertificateClient FailureThe server was unable to validate a certificate for the domain that signed the request.
438 Invalid Identity HeaderClient FailureThe server obtained a valid certificate that the request claimed was used to sign the request, but was unable to verify that signature.
439 First Hop Lacks Outbound SupportClient FailureThe first outbound proxy the user is attempting to register through does not support the "outbound" feature of RFC 5626, although the registrar does.
440 Max-Breadth ExceededClient FailureIf a SIP proxy determines a response context has 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 PackageClient FailureIf 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 the UA is willing to receive INFO requests.
470 Consent NeededClient FailureThe source of the request did not have the permission of the recipient to make such a request.
480 Temporarily UnavailableClient FailureCallee currently unavailable.
481 Call/Transaction Does Not ExistClient FailureServer received a request that does not match any dialog or transaction.
482 Loop DetectedClient FailureServer has detected a loop.
483 Too Many HopsClient FailureMax-Forwards header has reached the value ‘0’.
484 Address IncompleteClient FailureRequest-URI incomplete.
485 AmbiguousClient FailureRequest-URI is ambiguous.
486 Busy HereClient FailureCallee is busy.
487 Request TerminatedClient FailureRequest has terminated by bye or cancel.
488 Not Acceptable HereClient FailureSome aspect of the session description or the Request-URI is not acceptable.
489 Bad EventClient FailureThe server did not understand an event package specified in an Event header field.
491 Request PendingClient FailureServer has some pending request from the same dialog.
493 UndecipherableClient FailureRequest contains an encrypted MIME body, which recipient can not decrypt.
494 Security Agreement RequiredClient FailureThe server has received a request that requires a negotiated security mechanism, and the response contains a list of suitable security mechanisms for the requester to choose between– or a digest authentication challenge.
500 Server Internal ErrorServer FailureThe server could not fulfill the request due to some unexpected condition.
501 Not ImplementedServer FailureThe server does not have the ability to fulfill the request, such as because it does not recognize the request method. (Compare with 405 Method Not Allowed, where the server recognizes the method but does not allow or support it.
502 Bad GatewayServer FailureThe server is acting as a gateway or proxy, and received an invalid response from a downstream server while attempting to fulfill the request.
503 Service UnavailableServer FailureThe server is undergoing maintenance or is temporarily overloaded and so cannot process the request. A "Retry-After" header field may specify when the client may reattempt its request.
504 Server Time-outServer FailureThe server attempted to access another server in attempting to process the request, and did not receive a prompt response.
505 Version Not SupportedServer FailureThe SIP protocol version in the request is not supported by the server.
513 Message Too LargeServer FailureThe request message length is longer than the server can process.
580 Precondition FailureServer FailureThe server is unable or unwilling to meet some constraints specified in the offer.
600 Busy EverywhereGlobal FailureAll possible destinations are busy. Unlike the 486 response, this response indicates the destination knows there are no alternative destinations (such as a voicemail server) able to accept the call.
603 DeclineGlobal FailureThe destination does not wish to participate in the call, or cannot do so, and additionally the destination knows there are no alternative destinations (such as a voicemail server) willing to accept the call.
604 Does Not Exist AnywhereGlobal FailureThe server has authoritative information that the requested user does not exist anywhere.
606 Not AcceptableGlobal FailureThe user's agent was contacted successfully but some aspects of the session description such as the requested media, bandwidth, or addressing style were not acceptable.
607 UnwantedGlobal FailureThe called party did not want this call from the calling party. Future attempts from the calling party are likely to be similarly rejected.