Cisco SIP IP Phone Administrator's Manual page 106

SIP Responses
4xx Response
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
Cisco SIP IP Phone Administrator Guide
A-6
Supported?
See comments
See comments
See comments
Yes
Yes
Yes
Comments
The Cisco SIP IP phone does not generate these 5xx responses. For
an incoming response, the SIP IP phone initiates a graceful call
disconnect.
Appendix A SIP Compliance with RFC 3261 Information
Comments
This response is received only by the phone in this
release. The user is notified if this response is
received.
If this response is received, the user is notified that
the callee is temporarily unavailable (perhaps not
logged on), and any retry information is displayed.
This response is received only by the phone in this
release. The user is notified if this response is
received.
This response is received only by the phone in this
release.
If a new contact is received, the phone might
reinitiate the call.
The Cisco SIP IP 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.
This response indicates that the initial request is
terminated with a BYE or CANCEL request.
The Cisco SIP IP phone receives and generates this
response.