SIP Response Codes

The SIP message structure a well-defined, text-based format. SIP response codes are basically responses to SIP requests. Below is a quick list of SIP Response Codes. A more detailed compilation can be found here.

1xx—Informational Responses

* 100 Trying : Extended search being performed may take a significant time so a forking proxy must send a 100 Trying response
* 180 Ringing
* 181 Call Is Being Forwarded
* 182 Queued
* 183 Session Progress

2xx—Successful Responses

* 200 OK
* 202 accepted: It Indicates that the request has been understood but actually can't be processed

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 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.)
* 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, 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