On 10/9/13 11:37 AM, Despina Kitsou wrote:
>
> Hello,
>
> 180 and 183 have the same To-Tag, the first one contain SDP and connects
> early media (announcement/in-band) that A-side SIP device hears, but no
> indication that announcement has stop is received, then 180 Ringing
> without SDP is received from A-side SIP device but the device does not
> generates local ring back tone.
> Is it a limitation of the device if it does not generate local ring back
> tone in that case,
Yes, I would consider this a limitation of the device.
Its not really a violation, because there aren't any formal rules about
what must be done in these cases. (The device isn't required to render
*anything*.)
> is a 199 needed in this case since we have one dialog??
A 199 would be incorrect in this case.
> Also according to standards 180 Ringing without SDP will trigger local
> ring back tone
> RFC3960:
Note that RFC3960 is *informational*, it is not normative.
It provides suggestions.
> With this in mind, a UAC should develop its local policy regarding
> local ringing generation. For example, a POTS ("Plain Old Telephone
> Service")-like SIP User Agent (UA) could implement the following
> local policy:
>
> 1. Unless a 180 (Ringing) response is received, never generate
> local ringing.
>
> *2. If a 180 (Ringing) has been received but there are no incoming
> media packets, generate local ringing.*
>
> 3. If a 180 (Ringing) has been received and there are incoming
> media packets, play them and do not generate local ringing.
>
> Note that a 180 (Ringing) response means that the callee is
> being alerted, and a UAS should send such a response if the
> callee is being alerted, regardless of the status of the early
> media session.
>
>
> Is there a known limitation on sip devices that if an early-media inband
> information is connected ( in our case announcement) then afterwards it
> cannot generate local ringing???
I'd say its just not a very well implemented device.
You could complain to its developer. But it isn't obligated to behave
better.
You could experiment with different ways of behaving, and see if you can
find something that works better with it. But of course that might cause
trouble with other devices.
Good luck,
Paul
> Thank you very much,
>
> Despina
>
>
>
> > Date: Wed, 9 Oct 2013 11:10:52 -0400
> > From: pkyzi...@alum.mit.edu
> > To: sip-implementors@lists.cs.columbia.edu
> > Subject: Re: [Sip-implementors] sip device ring back tone
> >
> > On 10/9/13 10:39 AM, Despina Kitsou wrote:
> > >
> > > Hello,
> > >
> > > I have the following issues regarding the :
> > >
> > > Firstly, A-SIP subscriber call to a TDM subscriber that has been
> ported now to a C-SIP subscriber.So A-SIP subscriber receives an 183
> Session progress with SDP in order for an announcement to be heard that
> this subscriber is ported and that you call is being diverted, then
> C-SIP subscriber is reached and sent 180 Ringing without SDP but my
> A-SIP device does not generate local ringing,
> > > Is that a limitation of the sip device to Switch Between Early
> Media and Local Ringing???PLEASE HELP ME!!
> >
> > More detail would be helpful.
> >
> > Are the 183 and 180 on different early dialogs (different to-tags), or
> > the same one?
> >
> > Does the early media from the 183 continue after the 180 is received, or
> > does it stop?
> >
> > If its all on one early dialog, then it should be clear (based on the
> > 180) to the caller that the call is ringing. While media is being
> > received it should be played. If it stops, then the caller ought to
> > generate local ringback.
> >
> > If these are on two different early dialogs, then it is tricky. The
> > caller doesn't know which of the two dialogs will eventually be
> > answered. It also doesn't know which dialog the media is coming from. So
> > the device has to take a lot of discretion in what it does. There is no
> > one right answer in this case. I'd be inclined to say it ought to behave
> > the same as if there was only one early dialog.
> >
> > The callee could help this along a bit by returning a 199 () on
> > the dialog containing the 183 to indicate that is done.
> >
> > Thanks,
> > Paul
> >
> > _______________________________________________
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> > Sip-implementors@lists.cs.columbia.edu
> > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
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