SIP Responses

SIP responses are the codes used by Session Initiation Protocol for communication. We have put together a list of all the SIP responses known.

1xx = Informational SIP Responses

100 Trying – Extended search is being perform so a forking proxy must send a 100 Trying response.

180 Ringing – The Destination User Agent has received the INVITE message and is alerting the user of  call.

181 Call Is Being Forwarded – Optional, send by Server to indicate a call is being forwarded.

182 Queued – Destination was temporarily unavailable, the server has queued the call until destination is available.

183 Session Progress – This response may be used to send extra information for a call which is still being set up.

199 Early Dialog Terminated – Send by the User Agent Server to indicate that an early dialog has been terminated.

2xx = Success Responses

200 OK – Shows that the request was successful

202 accepted – Indicates that the request has been accepted for processing , mainly used for referrals.

204 No Notification – Indicates that the request was successful but no response will be received.

3xx = Redirection Responses

300 Multiple Choices –  The address resolved to one of several options for the user or client to choose between.

301 Moved Permanently – The original Request URI is no longer valid, the new address is given in the Contact header.

302 Moved Temporarily – The client should try at the address in the Contact field.

305 Use Proxy – The Contact field details a proxy that must be used to access the requested destination.

380 Alternative Service – The call failed, but alternatives are detailed in the message body.

4xx = Request Failures

400 Bad Request – The request could not be understood due to malformed syntax.

401 Unauthorized – The request requires user authentication. This response is issued by UASs and registrars.

402 Payment Required –  (Reserved for future use) .

403 Forbidden – The server understood the request, but is refusing to fulfill it.

404 Not Found – The server has definitive information that the user does not exist at the (User not found).

405 Method Not Allowed – The method specified in the Request-Line is understood, but not allowed .

406 Not Acceptable – The resource is only capable of generating responses with unacceptable content.

407 Proxy Authentication Required – The request requires user authentication.

408 Request Timeout – Couldn’t find the user in time.

409 Conflict – User already registered (deprecated)

410 Gone – The user existed once, but is not available here any more.

411 Length Required – The server will not accept the request without a valid content length (deprecated).

413 Request Entity Too Large – Request body too large.

414 Request URI Too Long – Server refuses to service the request, the Req-URI is longer than the server can interpret.

415 Unsupported Media Type – Request body is in a non supported  format.

416 Unsupported URI Scheme – Request-URI is unknown to the server.

417 Uknown Resource-Priority – There was a resource-priority option tag, but no Resource-Priority header.

420 Bad Extension – Bad SIP Protocol Extension used, not understood by the server.

421 Extension Required – The server needs a specific extension not listed in the Supported header.

422 Session Interval Too Small – The request contains a Session-Expires header field with duration below the minimum.

423 Interval Too Brief – Expiration time of the resource is too short.

424 Bad Location Information – The request’s location content was malformed or otherwise unsatisfactory.

428 Use Identity Header – The server policy requires an Identity header, and one has not been provided.

429 Provide Referrer Identity – The server did not receive a valid Referred-By token on the request.

430 Flow Failed – A specific flow to a user agent has failed, although other flows may succeed.

433 Anonymity Disallowed – The request has been rejected because it was anonymous.

436 Bad Identity Info – The request has an Identity-Info header and the   URI scheme contained cannot be de-referenced.

437 Unsupported Certificate – The server was unable to validate a certificate for the domain that signed the request.

438 Invalid Identity Header – Server obtained a valid certificate used to sign a request, was unable to verify the signature.

439 First Hop Lacks Outbound Support – The first outbound proxy doesn’t support “outbound” feature.

470 Consent Needed – The source of the request did not have the permission of the recipient to make such a request.

480 Temporarily Unavailable – Callee currently unavailable.

481 Call/Transaction Does Not Exist – Server received a request that does not match any dialog or transaction.

482 Loop Detected – Server has detected a loop.

483 Too Many Hops – Max-Forwards header has reached the value ‘0’.

484 Address Incomplete – Request-URI incomplete.

485 Ambiguous – Request-URI is ambiguous.

486 Busy Here – Callee is busy.

487 Request Terminated – Request has terminated by bye or cancel.

488 Not Acceptable Here – Some aspects of the session description of the Request-URI are not acceptable.

489 Bad Event – The server did not understand an event package specified in an Event header field.

491 Request Pending – Server has some pending request from the same dialog.

493 Undecipherable – UndecipherableRequest contains an encrypted MIME body, which recipient can not decrypt.

494 Security Agreement Required – The server has received a request that requires a negotiated security mechanism.

5xx = Server Errors

500 Server Internal Error – The server could not fulfill the request due to some unexpected condition.

501 Not Implemented – The SIP request method is not implemented here.

502 Bad Gateway – The server, received an invalid response from a downstream server while trying  to fulfill a request.

503 Service Unavailable – The server is in maintenance or is temporarily overloaded and cannot process the request.

504 Server Time-out – The server tried to access another server while trying  to process a request, no timely response.

505 Version Not Supported – The SIP protocol version in the request is not supported by the server.

513 Message Too Large – The request message length is longer than the server can process.

580 Precondition Failure – The server is unable or unwilling to meet some constraints specified in the offer.

6xx = Global Failures

600 Busy Everywhere – All possible destinations are busy.

603 Decline – Destination cannot/doen’t wish to participate in the call,  no alternative destinations.

604 Does Not Exist Anywhere – The server has authoritative information that the requested user does not exist anywhere.

606 Not Acceptable – The user’s agent was contacted successfully but some aspects of the session description were not acceptable.