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Choose the appropriate tab for the set of SIP Response Codes in which you are interested:
Please report errors or omissions to Developing Solutions Support.
Read about our latest performance benchmark, verified by EANTC.
Choose the appropriate tab for the set of SIP Response Codes in which you are interested:
Response Code | Name | Description | dsTest OM | |
1XX | Provisional Response Codes | Used to indicate call progress. Except for 100 Trying, the responses are end to end | ||
100 | Trying | Extended search being performed may take a significant time so a forking proxy must send a 100 Trying response. | ||
180 | Ringing | Destination user agent received INVITE, and is alerting user of call. | ||
181 | Call is Being Forwarded | Servers can optionally send this response to indicate a call is being forwarded. | ||
182 | Queue | Indicates 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 In Progress | May be used to send extra information for a call which is still being set up. | ||
199 | Early Dialog Terminated | Can 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. |
Response Code | Name | Description | dsTest OM | |
2XX | Successful Response Codes | For indicating that a request has been accepted | ||
200 | OK | Indicates the request was successful. | ||
202 | Accepted | Indicates that the request has been accepted for processing, but the processing has not been completed. | ||
204 | No Notification | Indicates the request was successful, but the corresponding response will not be received. |
Response Code |
Name | Description | dsTest OM | |
3XX | Redirection Response Codes | Sent by redirect servers in response to INVITE; also known as redirect class responses | ||
300 | Multiple Choices | The 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301 | Moved Permanently | The original Request-URI is no longer valid, the new address is given in the Contact header field, and the client should update any records of the original Request-URI with the new value.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 Temporarily | The 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 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 |
Response Code |
Name | Description | dsTest OM | |
4XX | Client Failure Response Codes |
Indicate that the request cannot be honored as some errors are identified at the UAC side | ||
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. Sometimes (but not always) this means the call has been rejected by the receiver. | ||
404 | Not Found | The 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 Allowed | The method specified in the Request-Line is understood, but not allowed for the address identified by the Request-URI. | ||
406 | Not Acceptable | The 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 Required | The request requires user authentication. This response is issued by proxys. | ||
408 | Request Timeout | Couldn’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 | Confict | User already registered. Deprecated by omission from later RFCs. | ||
410 | Gone | The user existed once, but is not available here any more. | ||
411 | Gone | The user existed once, but is not available here any more. | ||
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 | The server is refusing to service the request because the Request-URI is longer than the server is willing to interpret. | ||
415 | Unsupported Media Type | Request body in a format not supported. | ||
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 received request contains a Session-Expires header field with a duration below the minimum timer. | ||
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 | The request has been rejected because it was anonymous. | ||
433 | Anonymity Disallowed | A specific flow to a user agent has failed. | ||
436 | Bad Identity-Info | Th URI scheme in the Identity-Info cannot be dereferenced. | ||
437 | Unsupported Certificate | The server was unable to validate a certificate for the domain that signed the request. | ||
438 | Invalid Identity Header | The 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 Support | The first outbound proxy the user is attempting to register through does not support the outbound feature. | ||
470 | Consent Needed | The source of the request did not have the permission of the recipient to make such a request. | ||
480 | Temporarily Unavailable | The callee currently unavailable. | ||
481 | Call/Transaction Does Not Exist | The server received a request that does not match any dialog or transaction. | ||
482 | Loop Detected | The server has detected a loop. | ||
483 | Too Many Hops | The Max-Forwards header has reached the value ‘0’. | ||
484 | Address Incomplete | The Request-URI is incomplete. | ||
485 | Ambiguous | The Request-URI is ambiguous. | ||
486 | Busy Here | The callee is busy. | ||
487 | Ambiguous | The Request has been terminated by a BYE or CANCEL. | ||
488 | Not Acceptable Here | Some aspect of the session description or the Request-URI is not acceptable. | ||
489 | Bad Event | The server did not understand an event package specified in an Event header field. | ||
491 | Request Pending | The server has some pending request from the same dialog. | ||
493 | Undecipherable | The 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. | ||
494 | Security Agreement Required | The request contains an encrypted MIME body, which recipient can not decrypt. |
Response Code |
Name | Description | dsTest OM | |
5XX | Server Failure Response Codes | Indicates that the request cannot be processed because of an error with the server | ||
500 | Server Internal Error | The server could not fulfill the request due to some unexpected condition. | ||
501 | Not Implemented | The server does not have the ability to fulfill the request, such as because it does not recognize the request method. | ||
502 | Bad Gateway | The 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 Unavailable | The 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 Timeout | The server attempted to access another server in attempting to process the request, and did not receive a prompt 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. | ||
580 | Precondition Failure | The server is unable or unwilling to meet some constraints specified in the offer. |
Response Code | Name | Description | dsTest OM | |
6XX | Global Failure Response Codes | Indicates the server knows that the request will fail wherever it is tried; therefor, the request should not be sent to other locations | ||
600 | Busy Everywhere | All possible destinations are busy. This response indicates the destination knows there are no alternative destinations (such as a voicemail server) able to accept the call. | ||
603 | Decline | The 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 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 such as the requested media, bandwidth, or addressing style were not acceptable. |