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Choose the appropriate tab for the set of SIP Response Codes in which you are interested:
Provisional Response Codes
| 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. |
Successful Response Codes
| 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. |
Redirection Response Codes
| 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| 301 | Moved Permanently | The original Request-URI is no longer valid, the new address is given in the Contact header field, and the client should update any records of the original Request-URI with the new value.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 |
Client Failure Response Codes
| 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. |
Server Failure Response Codes
| 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. |
Global Failure Response Codes
| 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. |