SIP response codes

SIP/2.0 allows six values for the first digit:

1xx: Provisional — request received, continuing to process the request;
- Provisional responses, also known as informational responses, indicate that the server contacted is performing some further action and does not yet have a definitive response. A server sends a 1xx response if it expects to take more than 200 ms to obtain a final response. Note that 1xx responses are not transmitted reliably. They never cause the client to send an ACK. Provisional (1xx) responses MAY contain message bodies, including session descriptions.
2xx: Success — the action was successfully received, understood, and accepted;
3xx: Redirection — further action needs to be taken in order to complete the request;
4xx: Client Error — the request contains bad syntax or cannot be fulfilled at this server;
5xx: Server Error — the server failed to fulfill an apparently valid request;
6xx: Global Failure — the request cannot be fulfilled at any server.

SIP response class1

SIP response codes, class 1: Provisional messages

These are sent within a SIP dialogue

· 100 Trying

· 180 Ringing

· 181 Call Is Being Forwarded

· 182 Queued

· 183 Session Progress

SIP Response class2

SIP Response codes: 2xx class

The 2xx class of responses indicates a success

SIP Response class3

SIP response codes, class 3xx

The 3xx class of responses indicates a redirection of the call

SIP Response class4

400 Bad Request
401 Unauthorized: Used only by registrars. Proxys should use proxy authorization 407
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: Couldn't find the user in time
409 Conflict
410 Gone: The user existed once, but is not available here any more.
413 Request Entity Too Large
414 Request-URI Too Long
415 Unsupported Media Type
416 Unsupported URI Scheme
420 Bad Extension: Bad SIP Protocol Extension used, not understood by the server
421 Extension Required
422 Session Interval Too Small
423 Interval Too Brief
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
491 Request Pending
493 Undecipherable: Could not decrypt S/MIME body part

SIP Response class5

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

SIP Response class6