Practically, the Redirector could be also an AS which can use the 18x to play some voice announcement (early media). I don't think anything wrong with this behavior.
Jerry > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] Behalf Of Smith, > Nathan > Sent: Sunday, February 04, 2007 6:49 PM > To: [email protected] > Subject: [Sip-implementors] SIP Redirect Server: Returning 180 > Ringingbefore 302 Moved Temp > > > Hi All, > > Quick question on what the "correct" behaviour of a SIP redirect server > is expected to be, in a Voice Telephony environment where the redirector > is used solely to spread call load over a number of dedicated > Application Servers: > > Initiating AS Redirector Destination AS > > INVITE-----------------> > <-------------100 Trying > <-------------180 Ringing * > <-------------302 Moved Temp > ACK--------------------> > INVITE----------------------------------------> > <------------------------------------100 Trying > <------------------------------------180 Ringing > <------------------------------------200 OK > ACK-------------------------------------------> > > Ideally, a SIP Redirect Server should only be implemented with a > "limited Transaction User layer, which has access to a location > service". You would therefore expect that the server does not act on > behalf of the end service (the destination AS has this responsibility), > and is only responsible for responding with appropriate level of > information about how to reach the end service (via 3xx) or any error > handling (4xx). > > As such, I would expect that there should be no need to send further > provisional 1xx responses after a 100 Trying - especially as a 180 is > generally used to indicate that the eventual destination has been found, > and is being alerted (which is not the case with a redirect server - as > the 302 indicates that in fact the end service is still yet to be > contacted). > > So I would then make the assertion that the 180 Ringing indicated by the > (*) is in fact superfluous - and I would argue - that it is actually > incorrect in a redirect server scenario to implement the stack in this > way. Any thoughts? > > Regards > > Nathan Smith > Senior VoIP Specialist > Enterprise Fixed & IP Calling > Telstra Corporation Ltd > Email: [EMAIL PROTECTED] > > DISCLAIMER: > The information contained in this email message may be confidential. If > you are not the intended recipient, any use of, interference with, > disclosure or copying of this material is unauthorised and prohibited. > If you have received this message in error, please notify me by reply > email and then delete the message. > > _______________________________________________ > Sip-implementors mailing list > [email protected] > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors > _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
