Please refer rfc 3264 section 8.3.2
On Nov 5, 2014 12:50 AM, "Sourav Dhar Chaudhuri" <sourav_mi...@yahoo.co.in>
wrote:

> Hi Ankur,
>    Thanks for your clarification. My question still remains.
>
>    In the offer from A does not have the support for payload no 101. So
> why you are saying it A SHOULD use  it towards B instead of BYE. where
> only B has mentioned any payload support on 101. What is the basis of A
> should do that activity ? Is it best possible SDP negotiation in case not
> exact matching ?
>
>   Moreover how will B sends the telephony event with payload 99. B has not
> mentioned it support for payload 99.
>
> Thanks
>
> Sourav
>
>
>   On Tuesday, 4 November 2014 9:48 PM, ankur bansal <abh.an...@gmail.com>
> wrote:
>
>
> Hi Saurav
>
> I believe there is no issue due to  rtpmap as its required only for
> dynamic payloads and not for static payloads .
> Reason of UE A sending BYE could be mismatch in payload no for telephony
> event .
> A is sending 99 but B is sending 101 .So A finds this wrong and send BYE
> But UE A* should not* send BYE and accept this answer sending telephony
> events with payload no 101 instead of 99 which is expected by UE B.
> And UE B needs to send telephony events with payload no 99 towards UE A.
> Hope this helps
>
> Thanks & Regards
> Ankur Bansal
>
> On Tue, Nov 4, 2014 at 9:12 PM, Sourav Dhar Chaudhuri <
> sourav_mi...@yahoo.co.in> wrote:
>
> Hi,
>    I am observing a behavior SDP negotiation. In the Below Example just
> After Media Negotiation. A is sending BYE without any media flow . Please
> refer the below call flow & my query.
>
>
> A ---------------------------  INVITE with SDP  ------------------------->
> B
>
> ########## SDP details in Offer ##############
>
> v=0
> o=- 1414764441 1414764441 IN IP4 172.29.62.182
> s=Basic Session
> c=IN IP4 172.29.62.182
> t=0 0
> m=audio 37620 RTP/AVP 18 8 0 99 106 107
> a=rtpmap:99 telephone-event/8000
> a=fmtp:99 0-15
> a=rtpmap:106 PCMU/8000
> a=rtpmap:107 PCMA/8000
> a=ptime:20
>
> A <------------------------- 100 Trying
> --------------------------------------  B
>
> A  <------------------------ 180 Ringing
> (unreliable)------------------------------------- B
>
> A  <------------------------ 200 OK with SDP
> ------------------------------ B
>
> ########## SDP details in Answer ################
>
> v=0
> o=0000000000 37448557 1 IN IP4 172.29.62.11
> s=-
> c=IN IP4 172.29.62.11
> t=0 0
> m=audio 53378 RTP/AVP 8 101
> a=sendrecv
> a=ptime:20
> a=rtpmap:101 telephone-event/8000
> a=fmtp:101 0-15
>
> A --------------------------  ACK
> -------------------------------------------> B
> A --------------------------  BYE
> ------------------------------------------>  B
>
> the call is getting disconnected without any media transfer.
>
> I  can see there are  six codecs [ 18 8 0 99 106 107 ] with attribute for
> only for three [ 99 106 107 ] in  SDP offer. Those three [ 99 106 107 ]
> only  having rtpmap details.
>
> But in SDP answer two codec [ 8 101 ] with attribute for only [ 101 ]. The
> rtpmap is also for only [ 101 ].
>
> So is the A is behaving correctly ?   Whether there is failure in SDP
> negotiation? If yes then why?
>
>
>
>
> Regards,
> Sourav Dhar Chaudhuri
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