Hi Roman,
On Tue, Apr 23, 2019 at 05:33:37PM -0400, Roman Shpount wrote:
> The most basic use case is click-to-call scenario. You have a web site or
> an application that imitates a call between two SIP end points. User clicks
> the web site which causes some sort of SIP application server to
I still don't get it, I'm sorry:
On Tue, Apr 23, 2019 at 05:34:21PM -0400, Paul Kyzivat wrote:
> 1) it doesn't have any idea what codecs, or even what media, either of
> the endpoints support.
Yes, but how does a late offer confer this knowledge in some materially
different way to a normal one?
On 4/23/19 5:12 PM, Alex Balashov wrote:
Paul,
Why can’t it do that with an offer in the initial invite?
Because:
1) it doesn't have any idea what codecs, or even what media, either of
the endpoints support.
2) since it isn't planning on terminating the media it has no media
address to
Alex,
The most basic use case is click-to-call scenario. You have a web site or
an application that imitates a call between two SIP end points. User clicks
the web site which causes some sort of SIP application server to send an
INVITE without an offer sent to SIP end point 1. SIP application
Paul,
Why can’t it do that with an offer in the initial invite?
—
Sent from mobile, with due apologies for brevity and errors.
> On Apr 23, 2019, at 5:10 PM, Paul Kyzivat wrote:
>
> Alex,
>
> A classic use case is 3PCC: A device in the middle wants to broker a call
> between two other
Alex,
A classic use case is 3PCC: A device in the middle wants to broker a
call between two other endpoints. A priori it doesn't know the
capabilities of either of those endpoints, and doesn't want to put
itself in the media path as a transcoder. So it asks one end to provide
an offer so it
If we are strictly discussing the interaction between two UAs, then I am
at a
loss as well regarding the practical usefulness of late SDP offers and
would be
interested in hearing other opinions.
However, when we have the third, middling party is where things get
interesting.
Take, for
Hi Liviu,
Thank you for your answer. However, I’m afraid I still don’t quite understand —
perhaps it is a matter of being thick-skulled, and if so, for that I apologise
in advance.
What exactly can be remediated by the caller that cannot be addressed by the
parties simply agreeing on a codec
Hi Alex,
In my experience, late SDP negotiation has proved to be an essential
mechanism for codec transcoding. For example, given this setup:
UA-1 B2BUA UA-2
| INVITE | INVITE |
|-->|->|
|
Hi,
Trying to fill a gaping hole in my knowledge:
What is the actual purpose of late SDP offers (no SDP in initial INVITE,
SDP offer in 2xx reply, SDP answer in end-to-end ACK)?
RFC 3261 mentions them, of course, but I’ve only ever seen them used in
Cisco (CCM and IOS voice gateway) land.
I
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