[SIPForum-discussion] difference in the sdp for the calls !!

[Abhishek Jain]

Hi Vir,

Please see my comments inline.

Regards
Abhishek

On Sat, Dec 3, 2011 at 12:20 PM, virajith <vir356 at rediffmail.com> wrote:

>
> Dear all,
>
> I have  a query in relation to  2 different types of  sdp received in  the
> *INVITE* from  a sip provider for  incoming calls.
>
> Scenario 1
> =========>
>
> =======sdp  for few  calls==========
>
> v=0
> o=- 2341457 1 IN IP4 60.234.18.158
> s=-
> c=IN IP4 60.234.18.158
> t=0 0
> m=audio 30006 RTP/AVP 8 0 18 100
> a=fmtp:18 annexb=no
> a=fmtp:100 0-15
> a=ptime:20
> a=rtpmap:100 telephone-event/8000
>
> ===============================
>
>
> Scenario 2
> =========>
>
> ===========sdp for other calls===========
>
> v=0
> o=default 1322426685 1322426685 IN IP4 60.234.18.158
> s=-
> c=IN IP4 60.234.18.158
> t=0 0
> m=audio 30002 RTP/AVP 18 106 4 8 0
> a=sendrecv
> a=rtpmap:106 telephone-event/8000
> a=fmtp:106 0-15
> a=maxptime:90
>
> ============================================
>
>
> Now the questions I have is the following...
>
> 1>what are the codecs  and the dtmf  methods being advertised in scenario
> 1 ?
> <Abhishek> 8 0 18 : PCMA, PCMU, G.729 and supports DTMF : dynamic payload
> type 100 (supports dtmf events 0-15) . refer rfc 3551
>


> 2>what are the codecs  and the dtmf  methods being advertised in scenario
> 2 ?
> <Abhishek> 18 4 8 0: G.729, G.723, PCMA, PCMU and supports DTMF : dynamic
> payload type 106(supports dtmf events 0-15). refer rfc 3551



> 3>what is a=sendrecv ?

<Abhishek> "sendrec" means that the media will be supported bidirectional
> (in send and receive mode). Refer rfc 4566
>


> 4>also anything else that you can point out  that is different in the    2
> sdps   ?
>
> Thanks,
> Vir
>
>
>
>
>
>
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