[SIPForum-discussion] UAS Processing of the INVITE request

[Ashish Umrani]

Vijay,

One more word of caution. If you are attempting to use predeveloped B2BUA
l(ike Sylantro System) and if you place a TO tag in Initial invite, the
B2BUA gets into infinite llop of authentication. So don place TO tag in
Initial invite.

Re invites are multiple in nature, Music on Hold, Conference, any
notification etc all are re invites. Simply said any feature invoke is re
invite ( I am probably endorsing Sreekant here)

Ashish


On 8/13/07, sreekant nair <sreekant_nair at yahoo.com> wrote:
>
>  Hi Vijay,
>
> One of the means of distinguishing a new INVITE from a re-INVITE is the TO
> Tag. The presence of the TO-Tag indicates that this is a mid-call INVITE
> that belongs to a dialog.
> A typical scenario when a re-INVITE is sent (in a VOIP perspective) is
> HOLD/3way call/Conference etc. You need to out the original call on hold and
> call the next person and then conference all three. That would have a
> re-INVITE.
>
> So in between if the system crashes while on hold, the re-INVITE would
> come and not find that dialog.So assuming that the system crash was a
> fatal error, there may not have been time or the environmental conditions
> would not have been favorable to print/throw/display any kind of log. Even
> if it did , the log may not be a SIP-UAS log.
>
> Regards
> Sreekant
>
> ----- Original Message ----
> From: Donald Lee <baolovebao at gmail.com>
> To: Vijay T <vijaycec at yahoo.co.in>
> Cc: discussion at sipforum.org
> Sent: Sunday, August 12, 2007 9:56:04 PM
> Subject: Re: [SIPForum-discussion] UAS Processing of the INVITE request
>
> Hi Vijay:
>
>       Here are some of my considerations, please check them inline.
>       BR
>       Donald
>
>
>
> 2007/8/12, Vijay T <vijaycec at yahoo.co.in>:
> >
> > Dear All
> >           This is vijay...i have a doubt reg INVITE req processing...
> > During the handling of INVITE request(UAS core) RFC3261 states that in
> > the section
> >
> > 13.3 UAS Processing
> >
> > 13.3.1 Processing of the INVITE
> >
> >   3."If the request has a tag in the To header field but the dialog
> >      identifier does not match any of the existing dialogs, the UAS
> >      may have crashed and restarted"
> >
> > My Qns:
> > 1.Here the request itself fill the tag of the To header field.How???
>
>
> Donald: It doesn't mean that the request fill the tag. On example of this
> case: During an exist dialog one of the UE has some fatal error to reboot,
> so it doesn't send any request to the other UE. after the former one up
> again, if the other one want to send a re-INVITE to change the "current
> dialog", that would lead to this case.
>
> 2.In crashed & restarted  case why not UAS generated corresponding error
> > response for that???
>
> Donald: I think in this case there is no time for UAS to generate
> corresponding error response, it's dying:-P.
>
>
> and another separate query is
> > please tell me about "mid-dialog" request and when it'' happen???
>
>
> Donald: After a dialog is estabilished(an ACK in a dialog send
> successfully). Any request within this dialog(have the same
> Call-ID, From-Tag, To-Tag) will be called "mid-dialog" request.
>
> i'm little bit confused abt this request....
> >
> > Thanks in Advance
> > Vijay
> >
> >  ------------------------------
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> >
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>
>
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