Module 5: SIP Response Codes
Class List
1xx: Provisional Request received, continuing to process the request
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 Codes: 1xx class
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 Codes: 2xx class
The 2xx class of responses indicates a success
• 200 OK
• 202 Accepted: Used for referrals
SIP Response Codes: 3xx class
The 3xx class of responses indicates a redirection of the call
• 300 Multiple Choices
• 301 Moved Permanently
• 302 Moved Temporarily
• 305 Use Proxy
• 380 Alternative Service
SIP Response Codes: 4xx class
Request failures
• 400 Bad Request
• 401 Unauthorized: Used only by registrars.
• 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
• 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
• 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 Codes: 5xx class
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
SIP Response Codes: 6xx class
Global failures
• 600 Busy Everywhere
• 603 Decline
• 604 Does Not Exist Anywhere
• 606 Not Acceptable
