Hi Aditya ,
This media attribute line usually comes from UAS in 183 response in case of
preconditions (QOS) .
Sending this ,UAS wants confirmation from UAC that whenever resource
reservation (dedicated bearer) done
please send Update to me ,then I will pass Incoming call indication to user
.
-----------------INVITE
sdp(a=inactive)-------->Incoming call indication not passed to user
Resource reservation starts<---------------183
sdp(a=inactive)-------------- Resource reservation starts
----------------PRACK
------------------->
<----------------200 ok
------------------- -
Resource reservation
done Resource
reservation done
--------------UPDATE
sdp(a=sendrecv) ---------> Pass incoming call indication to user
<----------------200 ok
sdp(a=sendrecv) ---------
<----------------180
Ringing---------------
<----------------200ok(invite)--------------
------------------ACK------------------------->
This is very basic scenario ,and there are multiple other scenarios
depending upon :
1.If any party already have resource reservation present
2.If UAS don't understand preconditions
3.If delay happens in resource reservation then UAC will have delay in
sending Update sdp and UAS will have
delay in sending 180 ringing .
The scenario where UAS don't need Confirmation from UAC regarding resource
reservation :
1 .When UAC sends INVITE with qos parameters saying UAC already have
resource reservation and UAC wants
UAS to reserve resources before establishing call .
Resource reservation done
-----------------INVITE
sdp(a=sendrecv)-------->Incoming call indication not passed to user
<---------------183
sdp(a=sendrecv)-------------- Resource reservation starts
----------------PRACK
------------------->
<----------------200 ok
------------------- -
Resource
reservation done then Pass incoming
call indication to user
<----------------180
Ringing---------------
<----------------200ok(invite)--------------
------------------ACK------------------------->
2.If UAS don't support preconditions ...In this case UAS directly send 180
ringing and then 200 ok sdp.
Thanks & regards
Ankur Bansal
On Thu, Sep 26, 2013 at 10:44 PM, Aditya Kumar <adityakumar...@yahoo.com>wrote:
> Hi,
>
> Can any one please explain me about
> a=conf:qos remote sendrecv
> this header in detail. I did not understand that.
>
> what is the confirmation for? is it only Target can sent it?
>
> why do we need conformation when in the
> a=curr:qos remote none
> The target can tell its current state and change if needed in
> a=des:qos mandatory remote sendrecv
>
> -Adi
>
>
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