List of SIP response codes.
SIP responses are the codes used by Session Initiation Protocol for communication.
They complement the SIP Requests,
which are used to initiate action such as a phone conversation.
Note that the Reason Phrases of the responses listed below are only the recommended examples,
and can be replaced with local equivalents without affecting the protocol.
1xxInformational Responses
100Trying: extended search being performed may take a significant time so a forking proxy must send a 100 Trying response
180Ringing
181Call Is Being Forwarded
182Queued
183Session Progress
2xxSuccessful Responses
200OK
202accepted: It Indicates that the request has been understood but actually can't be processed
3xxRedirection Responses300 Multiple Choices
301Moved Permanently
302Moved Temporarily
305Use Proxy
380Alternative Service
4xxClient Failure Responses
400Bad Request
401Unauthorized (Used only by registrars or user agents. Proxies should use proxy authorization 407)
402Payment Required (Reserved for future use)
403Forbidden
404Not Found (User not found)
405Method Not Allowed
406Not Acceptable
407Proxy Authentication Required
408Request Timeout (Couldn't find the user in time)
409Conflict
410Gone (The user existed once, but is not available here any more.)
412Conditional Request Failed
413Request Entity Too Large
414Request-URI Too Long
415Unsupported Media Type
416Unsupported URI Scheme
417Unknown Resource-Priority
420Bad Extension (Bad SIP Protocol Extension used, not understood by the server)
421Extension Required
422Session Interval Too Small
423Interval Too Brief
424Bad Location Information
428Use Identity Header
429Provide Referrer Identity
433Anonymity Disallowed
436Bad Identity-Info
437Unsupported Certificate
438Invalid Identity Header
480Temporarily Unavailable
481Call/Transaction Does Not Exist
482Loop Detected
483Too Many Hops
484Address Incomplete
485Ambiguous
486Busy Here
487Request Terminated
488Not Acceptable Here
489Bad Event
491Request Pending
493Undecipherable (Could not decrypt S/MIME body part)
494Security Agreement Required
5xxServer Failure Responses
500Server Internal Error
501Not Implemented: The SIP request method is not implemented here
502Bad Gateway
503Service Unavailable
504Server Time-out
505Version Not Supported: The server does not support this version of the SIP protocol
513Message Too Large
580Precondition Failure
6xxGlobal Failure Responses
600Busy Everywhere
603Decline
604Does Not Exist Anywhere
606Not Acceptable


Siemens 7xx-Extended Codes
Attention: The following is a list of SIP Codes belonging to the 7xx, 8xx, 9xx classes (applicative) and used by Siemens in their Gigaset products.
They are not documented by any SIP RFC and other companies and applications may override them without notice.
701The called party has hung up
702VoIP socket error
703Connection cancelled because of timeout
704Connection interrupted because of a SIP error
705SIP memory error
706SIP transaction memory error
751Busy tone: No codec match between the calling and called party
810General socket layer error.
811General socket layer error: Wrong socket number
812General socket layer error: Socket is not connected.
813General socket layer error: Memory error
814General socket layer error: Socket not available – check IP settings/connection problem/VoIP setting incorrect
815General socket layer error: Illegal application on the socket interface
922No DNS server known
923DNS name resolution failed
924Insufficient resources for DNS name resolution
925URL error


SIP Error Messages
The following table shows the most common errors that can appear in the SIP messages with a detailed explanation.
These SIP error messages can be translated into Q.931 or DSS1 (ISDN) error messages: The SIP errors and the DSS1 and Q.931 errors are mapped as you can see in the following table.
Table: Mapping between SIP events and DSS1 codes.
SIP eventDecimalHexDSS1 HEXCause
400 Bad request1277FFFInterworking, unspecified
401 Unauthorized5739B9Bearer capability not authorized
402 Payment required211595Call rejected
403 Forbidden5739B9Bearer capability not authorized
404 Not found10181Unallocated (unassigned) number
405 Method not allowed1277FFFInterworking, unspecified
406 Not acceptable1277FFFInterworking, unspecified
407 Proxy authentication required211595Call rejected
408 Request timeout10266E6Recover on Expires timeout
409 Conflict4129A9Temporary failure
410 Gone10181Unallocated (unassigned) number
411 Length required1277FFFInterworking, unspecified
413 Request entity too long1277FFFInterworking, unspecified
414 Request URI (URL) too long1277FFFInterworking, unspecified
415 Unsupported media type794FCFService or option not available
420 Bad extension1277FFFInterworking, unspecified
480 Temporarily unavailable181292No user response
481 Call leg does not exist1277FFFInterworking, unspecified
482 Loop detected1277FFFInterworking, unspecified
483 Too many hops1277FFFInterworking, unspecified
484 Address incomplete281C9CAddress incomplete (invalid number format)
485 Address ambiguous10181Unallocated (unassigned) number
486 Busy here171191User busy
487 Request cancelled1277FFFInterworking, unspecified
488 Not acceptable here1277FFFInterworking, unspecified
500 Internal server error4129A9Temporary failure
501 Not implemented794FCFService or option not implemented
502 Bad gateway3826A6Network out of order
503 Service unavailable633FBFService or option unavailable
504 Gateway timeout10266E6Recover on Expires timeout
505 Version not implemented1277FFFInterworking, unspecified
580 Precondition Failed472FAFResource unavailable, unspecified
600 Busy everywhere171191User busy
603 Decline211595Call rejected
604 Does not exist anywhere10181Unallocated (unassigned) number
606 Not acceptable583ABABearer capability not presently available