June 3, 2015
2:24 p.m.
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/