Just to add on, ISUP ACM message maps onto 180 ringing - this means the address resolution completed and remote party (UAS) been alerted, hence UAC can generate the local ring back tone to user
ISUP CPG message carries ISUP event codes which will maps onto different provisional responses. Probably "rfc3398 ISUP - SIP mapping" would give you more insight into the details... Regards, Nataraju A B Sonus Networks Ind Pvt Ltd > From: [EMAIL PROTECTED] [mailto:sip-implementors- > [EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] > Sent: Thursday, September 21, 2006 10:16 PM > To: [email protected] > Subject: Re: [Sip-implementors] Doubts about provisional responses > > From: varun <[EMAIL PROTECTED]> > > 1> In what cases should 180 be definitely be send as a > response.A 180 response can actually contain the > SDP info.Assuming that reliability PRACK for > provisional responses is implemented, can a two way > audio session > be established before the caller has got a 200 OK. > > > 2>Also, 183 is basically used when the call goes > across different networks.Why can't simply 180 be > used.. > > How are 180 and 183 different from each other? > > The important difference is that 180 asserts that alerting has started > at the UAS. 183 indicates that the call is being processed (by some > entity), but does not imply that a destiantion is being alerted. > > 3>coming to early media, once the caller has send an invite it is > ready to receive media( you can play announcements to the caller), > what has 183 got to do with early media? > > "once the caller sent an INVITE containing SDP" (it is possible to > send an INVITE without SDP.) > _______________________________________________ > 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
