In my experience, some systems will not route advance on a non-200 response if pre-session media exists, e.g. a 183 voice reject before 603 final response, but will route advance if there is no pre-session media. In this context, calling parties using least-cost routing with multiple vendors would be expected to produce one call attempt total if there is pre-session media, and one attempt *per vendor/route* if there is no pre-session media. If you can spare the media bandwidth and channels to provide a brief voice reject, this may reduce the total number of attempts regardless of cause code. Regards, *Calvin Ellison* Voice Services Engineer calvin.ellison at voxox.com +1 (213) 285-0555 ----------------------------------------------- *voxox.com <http://www.voxox.com/> * 9276 Scranton Rd, Suite 200 San Diego, CA 92121 [image: Voxox] On Tue, Jun 2, 2015 at 1:58 PM, Peter Beckman <beckman at angryox.com> wrote:
I offer a feature to our customers that allows them to configure their DID to respond with "This number is disconnected" message for specific, annoying callers, based on their CallerID.
Some customers send a Busy signal (486 BUSY) for these annoying callers. It seems that some Robocallers will retry numbers that ring busy repeatedly, sometimes annoyingly aggressively.
I'm switching the default to declining the call, which brings me to which SIP response is correct and/or ideal.
From the RFC: https://www.ietf.org/rfc/rfc3261.txt
Section 21.4.5 404 Not Found
The server has definitive information that the user does not exist at the domain specified in the Request-URI. This status is also returned if the domain in the Request-URI does not match any of the domains handled by the recipient of the request.
Section 21.6.2 603 Decline
The callee's machine was successfully contacted but the user explicitly does not wish to or cannot participate. The response MAY indicate a better time to call in the Retry-After header field. This status response is returned only if the client knows that no other end point will answer the request.
We are currently sending a 603 Decline, which seems appropriate given the nature.
However we also get calls to numbers we service which are not active, in which case 404 Not Found seems more appropriate.
What is the real-world behavior of the calling party for these responses? If I change the cause code, will there be unintended consequences?
Any suggestions or experience is appreciated.
Beckman --------------------------------------------------------------------------- Peter Beckman Internet Guy beckman at angryox.com http://www.angryox.com/ --------------------------------------------------------------------------- _______________________________________________ VoiceOps mailing list VoiceOps at voiceops.org https://puck.nether.net/mailman/listinfo/voiceops