Ranga,
 
There are a couple settings on the SMC that can control code
negotiation. These settings have affected interaction with Piolycom in
the past. They are:
Honor first codec
And
Mid-call codec optimizing
Issue in Polycom was http://track.sipfoundry.org/browse/XTRN-521
<http://track.sipfoundry.org/browse/XTRN-521>  
 
In order to use these two settings the SMC must be provisioned off the
system.  

May not be related but thought it may help.

Al
 
From: [email protected]
[mailto:[email protected]] On Behalf Of M.
Ranganathan
Sent: Wednesday, October 21, 2009 2:12 AM
To: sipX developers
Subject: [sipX-dev] Skype is confused by Multiple codec in 200 OK
responseand a possible solution.
 
The following problem relates to several JIRA issues involving Skype and
the SMC phone.

Skype sends an INVITE (SDP) to the smc phone. The SMC phone returns
multiple codec choices in the 200 OK for the response. This completely
confuses the Skype SIP trunk. I made numerous tries  to compensate for
this using re-INVITEs so as to make it dynamic and end to end but
nothing completely worked for all scenarios. I am wondering if the right
strategy would be as follows:


Skype sends an SDP offer to the SMC phone. 

Let A be the set of codecs in the OFFER.
Let B be the set of codecs in the Answer.

SipXbridge computes the intersection of A and B and picks a single codec
from that intersection to send as an answer back to Skype.

This is not the same thing as clamping down the codecs or using a
predefined  exclude list but I think it will solve the interoperability
issue with skype.

Would this be a good thing for sipxbridge to implement? 

Regards,

Ranga.


-- 
M. Ranganathan
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