On 5/29/15 1:33 PM, Ambrish Kumar wrote:
Hi Paul and Adelia,
Thanks for the prompt response. So as per standard its feasible to
relay the RTP media as soon as offer answer is completed i.e. even
after reliable 18x response.
Even after an *un*reliable 1xx response. And one way media even before
any answer has been sent.
I agree RBT should be heard to Fanout number(LEA) but what I need to
I don't know what RBT is.
implement is to send actual RTP. I am not sure if any UE microphone get
activated during 18x.
As I described, calls to some callees probably won't work right if the
microphone (and DTMF) aren't enabled during early media.
I believe this is unrealistic ask. Please suggest.
*What* is unrealistic? Do you mean there is some technical impediment to
doing it? Or that it *shouldn't* be done? Or that it makes no sense to do?
Thanks,
Paul
Regards,
Ambrish
On Fri, May 29, 2015 at 10:37 PM, Paul Kyzivat <pkyzi...@alum.mit.edu
<mailto:pkyzi...@alum.mit.edu>> wrote:
On 5/29/15 12:11 PM, Ambrish Kumar wrote:
Dear Team,
I am working on Lawful interception and integrating our IMS
nodes (SBC)
with LEA. We have got a very unusual ask form IB/RAW where they
want to
listen the RTP flow before call is actually answered by “B”
We need your help and confirmation from any RFC which clarifies
when does
Media should start flowing in network :
1. Is it possible RTP media should start flowing right after
offer-answer
model is completed say after 18x response?
2. Or RTP Media should start flowing after 200 OK ACK response.
>From a SIP perspective, media can start flowing to the offerer as
soon as the offer is sent. (Of course, from a practical perspective
it also can't be sent until the offer has been received by the
device that will be sending.) Note that this can be long before the
O/A has been completed.
And then media can start flowing to the answerer as soon as the
answer has been sent. Practically this means when the offerer has
received the answer SDP. (Note that technically the O/A isn't
complete until the answer is sent in a *reliable* response. But for
the purposes here it is sufficient if it was sent in an unreliable
response that actually reaches the offerer.)
But not all deployments are so lenient. In particular, IIUC, IMS
"gates" the media streams until the answer reaches the caller's
outbound proxy. So, if you understand the details of your deployment
you can take advantage of knowledge.
Note that there are some extreme cases of early media that are
deployed. Some call centers may send media (not just ringback) in
both directions for an extended period of time, until the call is
assigned to an agent. The entire IVR interaction, with DTMF from the
caller, may be conducted using early media.
I know most of implementation start pushing media after 200 OK
ACK. But
does standard mandates to start flow TWO WAY RTP right after
offer-answer
model is completed.
It doesn't mandate that it MUST start flowing. But it does mandate
that it MAY start flowing.
Thanks,
Paul
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