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Viewing SIP response codes is an important phase of signaling analysis. You can quickly locate faults based on SIP response codes in the signaling process.
A response code contains three digits. The first digit indicates the response type, and the other two digits further explain the response code in detail. The following table describes the response code types and description. Those in bold are common response codes that you need to pay attention to.
Table 1 Description of SIP responses
Message Type |
Description |
Status Code |
Function |
1xx |
Call progress response, which indicates that a request has been received and is being processed. |
100 |
Trying |
180 |
Ringing |
||
181 |
Call Is Being Forwarded |
||
182 |
Queued |
||
183 |
Announcement Playback |
||
2xx |
Success response, which indicates that a request has been accepted and processed. |
200 |
OK |
3xx |
Redirection response. A further action is required to complete a request. |
300 |
Multiple Choices |
301 |
Moved Permanently |
||
302 |
Moved Temporarily |
||
303 |
See Other |
||
305 |
Use Proxy |
||
380 |
Alternative Service |
||
4xx |
Client error response, which indicates that a request message contains a syntax error or the SIP server cannot process the request message. |
400 |
Bad Request |
401 |
Unauthorized |
||
402 |
Payment Required |
||
403 |
Forbidden |
||
404 |
Not Found |
||
405 |
Method Not Allowed |
||
406 |
Not Acceptable |
||
407 |
Proxy Authentication Required |
||
408 |
Request Timeout |
||
410 |
Gone |
||
412 |
Conditional Request Failed |
||
413 |
Request Entity Too Large |
||
414 |
Request-URI Too Long |
||
415 |
Unsupported Media Type |
||
416 |
Unsupported URI Scheme |
||
420 |
Bad Extension |
||
421 |
Extension Required |
||
423 |
Session Interval Too Small |
||
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 (mainly media incompatibility) |
||
491 |
Request Pending |
||
493 |
Undecipherable |
||
5xx |
Server error response, which indicates that the SIP server cannot process messages due to a server error. |
500 |
Server Internal Error |
501 |
Not Implemented |
||
502 |
Bad Gateway |
||
503 |
Service Unavailable |
||
504 |
Server Time-out |
||
505 |
Version Not Supported |
||
513 |
Message Too Large |
||
580 |
Precondition Failure |
||
6xx |
Global error response, which indicates a request cannot be fulfilled on any SIP servers. |
600 |
Busy Everywhere |
603 |
Decline |
||
604 |
Does Not Exist Anywhere |
||
606 |
Not Acceptable |
Parent Topic: Common Methods for Locating Faults