A-6
Cisco SIP Proxy Server Administrator Guide
Appendix A SIP Compliance
RFC 2543 and RFC 3261
SIP Header Fields
Note All SIP header fields that concern the Cisco SPS are correctly handled and parsed except for the Hide
and Encryption header fields. Header fields that do not directly affect the Cisco SPS or that are unknown
to it are passed unaltered in the SIP request.
5xx Response—Server Failure Responses
500 Server internal error Server or gateway encountered an
unexpected error that prevents it from
processing the request.
Yes Generates and forwards this
response.
501 Not implemented Server or gateway does not support the
functions required to complete the
request.
502 Bad gateway Server or gateway received an invalid
response from a downstream server.
See Cisco SPS
action
Forwards this response.
503 Service unavailable Server or gateway is unable to process
the request due to an overload or
maintenance problem.
Yes Generates and forwards this
response.
504 Gateway timeout Server or gateway did not receive a
timely response from another server
(such as a location server).
See Cisco SPS
action
Forwards this response.
505 Version not supported Server or gateway does not support the
version of the SIP protocol used in the
request.
Yes
6xx Response—Global Responses
600 Busy everywhere Called party was contacted but is busy
and cannot take the call at this time.
See Cisco SPS
action
Forwards this response.
603 Decline Called party was contacted but cannot
or does not want to participate in the
call.
604 Does not exist anywhere Server has authoritative information
that the called party does not exist in the
network.
606 Not acceptable Called party was contacted, but some
aspect of the session description was
unacceptable.
Table A-3 SIP Responses (continued)
SIP Response Meaning Supported? Cisco SPS Action
