Hi, AFAIK there are three cases where 487 occurs:
1) The UAC sends a BYE during an early-dialog so the UAS replies a 200 OK for
the BYE and a 487 for the INVITE.
2) The UAC sends a CANCEL during an early-dialog so the UAS replies a 200 OK
for the BYE and a 487 for the INVITE.
3)
13.3.1 Processing of the INVITE
1. If the request is an INVITE that contains an Expires header
field, the UAS core sets a timer for the number of seconds
indicated in the header field value. When the timer fires, the
invitation is considered to be expired. If the invitation
expires before the UAS has generated a final response, a 487
(Request Terminated) response SHOULD be generated.
But I've seen 487 as the reply from some softswitches when the RURI is invalid
(international destination not allowed for example).
And also I've seen this 487 code as recommende reply for silent rejection
in "draft-ietf-bliss-ach-analysis":
5.3.3. Response codes
o Silent rejection/local. 487 could be used. This is the same
response code that would be used if a proxy were to issue a CANCEL
request.
But RFC 3261 says clearly:
21.4.25 487 Request Terminated
The request was terminated by a BYE or CANCEL request. This response
is never returned for a CANCEL request itself.
So, how valid is using 487 to decline a call?
Thanks.
--
Iñaki Baz Castillo
[EMAIL PROTECTED]
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