The choice of which response to generate to reject a call is a conscious decision on the part of the implementer depending on how he wants the rejection to be perceived by the caller.
A 486 is used when the *goal* is for the caller to be informed that the callee is busy. A 480 can be used so that the caller will think the callee isn't there. And a 603 is used to signal an explicit rejection. (It also, arguably, terminates any other forks, which may be a desirable feature for the callee.) Its not hard to imagine a phone with buttons for all three of these. Paul Iñaki Baz Castillo wrote: > Hi, SIP response codes for rejecting a call is a pain, each implementator > does > a different thing. RFC 3261 doesn't help a lot with the ambiguity of > 480/486/603 codes. > > In fact, when the user rejects explicitely a call (by pressing "Reject" > button) some UA's generate a "480 Temporarily Unavailable" (as SJphone, > Thomson S2030), others generate a "486 Busy Here" (as X-Lite, Siemens), and > others a "603 Decline" (as Twinkle). > > Personally I don't understant why "486 User Busy" is used for rejecting a > call. > Also, the use of "6XX" is not good since the UAS cancels the other ringing > UAS > (in case of parallel forking) what it's not good in many cases. > > So there is a "draft" [1] suggesting the use of "441 Decline". IMHO this MUST > exist in the original RFC 3261. The absence of it has generated the actuall > situation in which each implementator rejects a call in a different way. > > So... why this draft is still a draft? > > draft-worley-6xx-considered-harmful > http://tools.ietf.org/html/draft-worley-6xx-considered-harmful-00 > > Thanks for any explanation. > > > _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors