SIP response codes

SIP/2.0 allows six values for the first digit:

From the SIP Rfc:

The response codes are consistent with, and extend, HTTP/1.1 response codes. Not all HTTP/1.1 response
codes are appropriate, and only those that are appropriate are given here. Other HTTP/1.1 response codes
SHOULD NOT be used. Also, SIP defines a new class, 6xx.


  • 1xx: Provisional — request received, continuing to process the request;
    • Provisional responses, also known as informational responses, indicate that the server contacted is performing some further action and does not yet have a definitive response. A server sends a 1xx response if it expects to take more than 200 ms to obtain a final response. Note that 1xx responses are not transmitted reliably. They never cause the client to send an ACK. Provisional (1xx) responses MAY contain message bodies, including session descriptions.
  • 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.



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SIP/2.0 allows six values for the first digit:

From the SIP Rfc:

The response codes are consistent with, and extend, HTTP/1.1 response codes. Not all HTTP/1.1 response
codes are appropriate, and only those that are appropriate are given here. Other HTTP/1.1 response codes
SHOULD NOT be used. Also, SIP defines a new class, 6xx.


  • 1xx: Provisional — request received, continuing to process the request;
    • Provisional responses, also known as informational responses, indicate that the server contacted is performing some further action and does not yet have a definitive response. A server sends a 1xx response if it expects to take more than 200 ms to obtain a final response. Note that 1xx responses are not transmitted reliably. They never cause the client to send an ACK. Provisional (1xx) responses MAY contain message bodies, including session descriptions.
  • 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.



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Created by: oej, Last modification: Sun 04 of Jan, 2004 (13:47 UTC)
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