List of SIP (Session Initiation Protocol) Response Codes Print

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The following is a list explaining the different meanings of the SIP response codes you may encounter with various VOIP (Voice over IP) or FOIP (Fax over IP) providers.


1xx—Informational Responses


    100 Trying
    180 Ringing
    181 Call Is Being Forwarded
    182 Queued
    183 Session Progress


2xx—Successful Responses


    200 OK
    202 Accepted


3xx—Redirection Responses


    300 Multiple Choices
    301 Moved Permanently
    302 Moved Temporarily
    305 Use Proxy
    380 Alternative Service


4xx—Client Failure Responses


    400 Bad Request
    401 Unauthorized (Used only by registrars or user agents. Proxies should use “407 Proxy Authorization Required”)
    402 Payment Required (Reserved for future use)
    403 Forbidden
    404 Not Found (User not found)
    405 Method Not Allowed
    406 Not Acceptable
    407 Proxy Authentication Required
    408 Request Timeout (Could not find the user in time)
    409 Conflict
    410 Gone (The user existed once, but is not available here anymore.)
    412 Conditional Request Failed
    413 Request Entity Too Large
    414 Request-URI Too Long
    415 Unsupported Media Type
    416 Unsupported URI Scheme
    417 Unknown Resource-Priority
    420 Bad Extension (Bad SIP Protocol Extension used, or not understood by the server)
    421 Extension Required
    422 Session Interval Too Small
    423 Interval Too Brief
    424 Bad Location Information
    428 Use Identity Header
    429 Provide Referrer Identity
    433 Anonymity Disallowed
    436 Bad Identity-Info
    437 Unsupported Certificate
    438 Invalid Identity Header
    480 Temporarily Unavailable
    481 Call/Transaction Does Not Exist
    482 Loop Detected
    483 Too Many Hops
    484 Address Incomplete
    485 Ambiguous
    486 Busy Here
    487 Request Terminated
    488 Not Acceptable Here
    489 Bad Event
    491 Request Pending
    493 Undecipherable (Could not decrypt S/MIME body part)
    494 Security Agreement Required


5xx—Server Failure Responses


    500 Server Internal Error
    501 Not Implemented: The SIP request method is not implemented here
    502 Bad Gateway
    503 Service Unavailable
    504 Server Time-out
    505 Version Not Supported: The server does not support this version of the SIP protocol
    513 Message Too Large
    580 Precondition Failure


6xx—Global Failure Responses


    600 Busy Everywhere
    603 Decline
    604 Does Not Exist Anywhere
    606 Not Acceptable


Additional Comments


Note: Many of these error codes are currently not implemented in RelayFax 7 and above.



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