[VoiceOps] SIP 404 Not Found vs 603 Decline

[Alex Balashov]

487 is normally expected only for scenarios in which the INVITE 
transaction has been terminated due to a CANCEL'd branch. 3261 says:

    The request was terminated by a BYE or CANCEL request.  This
    response is never returned for a CANCEL request itself.

So, it's not an appropriate final negative response to send when not 
commanded by a CANCEL. I recommend 503 Service Unavailable.

-- Alex

-- 
Alex Balashov | Principal | Evariste Systems LLC
303 Perimeter Center North, Suite 300
Atlanta, GA 30346
United States

Tel: +1-800-250-5920 (toll-free) / +1-678-954-0671 (direct)
Web: http://www.evaristesys.com/, http://www.csrpswitch.com/