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/ ---------------------------------------------------------------------------