Appendix A
Compliance with RFC 3261
4xx Response
420 Bad Extension
480 Temporarily
Unavailable
481 Call Leg/Transaction
Does Not Exist
482 Loop Detected
483 Too Many Hops
484 Address Incomplete
485 Ambiguous
486 Busy Here
487 Request Canceled
488 Not Acceptable
5xx Response—Server Failure Responses
5xx Response
500 Internal Server Error
501 Not Implemented
502 Bad Gateway
503 Service Unavailable
504 Gateway Timeout
505 Version Not Supported
Supported?
Comments
Yes
The user is notified if this response is received.
If the phone does not understand the protocol
extension specified in the Require field, the 420 Bad
Extension response is generated.
Yes
The response is received only by the phone. The user
is notified if this response is received.
Yes
The user is notified if this response is received.
Yes
If a new contact is received, the phone might reinitiate
the call.
Yes
The phone generates this response if the called party is
off-hook and the call cannot be presented as a
call-waiting call. Upon receiving this response, the
phone notifies the user and generates a busy tone.
Yes
This response indicates that the initial request is
terminated with a BYE or CANCEL request.
Yes
When media cannot be negotiated properly, the phone
receives and generates this response.
Supported?
Comments
Yes
The phone initiates a graceful call disconnect, and the
user is notified.
Yes
Yes
Yes
Yes
Yes
Cisco SIP IP Phone Administrator Guide, Release 6.x and 7.x
SIP Responses
A-5