Some SIP phones and all PBXs display errors or a prompt using the SIP Response codes, this page contains a list of SIP codes that can help you diagnose problems.
The 1xx response codes are provisional messages sent indicating call progress.
- 100 Trying
- 180 Ringing
- 181 Call Is Being Forwarded
- 182 Queued
- 183 Session Progress
The 2xx class of response codes indicates success.
- 200 OK
The 3xx response codes indicate a redirection of the call.
- 300 Multiple Choices
- 301 Moved Permanently
- 302 Moved Temporarily
- 305 Use Proxy
- 380 Alternative Service
The 4xx response codes indicate request failures
- 400 Bad Request
- 401 Unauthorized: Used only by registrars. Proxies should use proxy authorization 407
- 402 Payment Required (Reserved for future use)
- 403 Forbidden
- 403 - Insufficient funds ( often related to the balance on the account or the Fraud control settings for the destination number)
- 404 Not Found: User not found ( Typically the PBX will deliver when an inbound route is not setup for the DID)
- 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 no longer available
- 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
The 5xx response codes indicate server failures.
- 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
The 6xxx response codes represent global failures.
- 600 Busy Everywhere
- 603 Decline
- 604 Does Not Exist Anywhere
- 606 Not Acceptable