In case of VoLTE, there will be multiple O/A before media establishment. On Wed, Jul 25, 2012 at 8:04 PM, Paul Kyzivat <[email protected]> wrote:
> I believe a primary motivation for PRACK was to support preconditions. > (RFC 3312) The need there was to do more than one O/A exchange prior to > answering an INVITE. It turns out that preconditions aren't widely used, > but the mechanism also turns out to be helpful in other cases. > > Thanks, > Paul > > On 7/25/12 2:25 AM, Aman wrote: > > Vikram, > > > > PRACK is for the reliability of provisional responses, 1XX messages > (except > > 100). The reliability of 2xx, 3xx, 4xx, 5xx, and 6xx responses to INVITEs > > is achieved using the ACK method. > > > > This is basically for the critical messages like 180 and 183 i.e when UAS > > wants the conformation from UAC that these 1XX messages are delivered > > properly. > > > > Check out the RFC3262 for more details on this. > > > > > > Cheers, > > Aman > > > > > > > > On Tue, Jul 24, 2012 at 12:48 PM, vikram > > <[email protected]>wrote: > > > >> > >> > >> > >> > >> > >> -- > >> > >> _______________________________________________ > >> 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 > > > > _______________________________________________ > Sip-implementors mailing list > [email protected] > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors > -- With Regards Venu 93484 89945 [email protected] _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
