Ramachandran Iyer wrote:
> inline,,,
>
> Paul Kyzivat <[EMAIL PROTECTED]> wrote:
>
> Ramachandran Iyer wrote:
>> inline...
>>
>> "Barman, Sibon B (Sibon)" wrote: Does anybody have any idea on how to handle
>> 180 with SDP --- will it be
>> handled the same way as 183 with SDP meaning the ringing would be remote
>> ringing rather than local ringing? Or 180 SDP will be handled as local
>> ringing irrespective of the presence or absence of SDP in 180.
>>
>> [Rama] If i understnad your question right, it revolves around when to apply
>> local ringing and when not. I think below set of rules (From 3960 should
>> help)... which basically says..
>> * Dont apply local ringing unless you get a 180
>> * Apply local ringing upon receivign of 180 (which does not have media
>> accompanying that 180)
>> * If 180 comes with media,,apply that media (so no local ringing required)
>
> Its not a matter of whether the "180 comes with media". The i80 may come
> with SDP, but it doesn't come with media. :-)
> [Rama] my bad.... i put it wrongly... did not mean that :)
Yes, I know. I was just giving you a hard time. :-)
> Its a matter of whether the UAC is *receiving* media at its media port,
> which could happen even without receiving SDP from the UAS. If media is
> being received, and a 180 has been received then the media should be
> played in preference to local ringback. If media is being received and a
> 180 has *not* been received, then the media should also be played.
>
> [Rama] Paul, presume there's no typo above,,, r u then saying that
> irrespective of whether 180 came or not.. as far as media is being sent from
> UAS to UAC, just keep playing the media.
Yep. The UAS could start sending media as soon as it receives the offer,
and that could be received before the answer. (Either just because it is
quicker, or because the 1xx was lost.)
The 183 is widely thought of as meaning "early media is coming", and it
is used that way, but it isn't the only way it can be used. And an
answer may be returned in a 180 as well.
In general receiving the answer is neither necessary nor sufficient for
getting early media. Getting an answer doesn't help with deciding to
receive media, because there is no requirement that the source of the
received media need not be the same as the destination for sent media.
(Which is what the answer provides.)
> That is the theory. In practice, many want to receive an answer before
> beginning to render media. You will have to make that choice.
In practice, some make more constraining assumptions, such as that
sending and receiving ports are the same, and that the answer must be
received before media will be accepted. You can of course choose to do
that if you wish, but then you have the risk that you will lose media
that you needed to receive.
Paul
> Paul
>
>
>
>
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