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

[Keyur Amin]

1>what are the codecs  and the dtmf  methods being advertised in scenario 1 ?
- Codecs are defined in the "m" line. Their description can be found in "a" lines, which is optional. DTMF method support seems to be for both out-of-band and in-band for both sdp.
- Codec ids mapping can be found in section 6 of rfc3551
AVP 8 0 18 100
m=audio 30006 RTP/AVP 8 0 18 100
a=fmtp:100 0-15

2>what are the codecs  and the dtmf  methods being advertised in scenario 2 ?
AVP 18 106 4 8 0
a=rtpmap:106 telephone-event/8000
a=fmtp:106 0-15

3>what is a=sendrecv ?
sendrecv would allow for send and receive media. Refer to section 6 for rfc4566



 
Thanks,
Keyur Amin

________________________________

 
 


________________________________
 From: virajith <vir356 at rediffmail.com>
To: "discussion at sipforum.org" <discussion at sipforum.org> 
Sent: Friday, December 2, 2011 11:50 PM
Subject: [SIPForum-discussion] difference in the sdp for the calls !!
 


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 ?

2>what are the codecs  and the dtmf  methods being advertised in scenario 2 ?

3>what is a=sendrecv ?

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


Thanks,
Vir







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