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List:       sip-implementors
Subject:    Re: [Sip-implementors] How to determine where to send RTP packet	in multi-proxy SIP network
From:       "Dale Worley" <dworley () nortel ! com>
Date:       2008-12-31 23:22:39
Message-ID: 1230765759.2950.13.camel () victoria-pingtel-com ! us ! nortel ! com
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On Tue, 2008-12-30 at 22:37 +0800, Serbang, Nabam (Nabam) wrote:
> So how u1 knows where to send RTP packet. Usually it will send to
> address present in Contact header.

U1 will *never* use the IP address in the Contact header to determine
where to send RTP packets, it will use the address in the 'c' line of
the SDP it receives.

There are problems ensuring that each UA will receive SDP that contains
'c' lines that contain usable addresses for SDP.  ICE can be used by the
UAs to decide what addresses to use.  Alternatively, the proxies
involved can edit the SDP to correct the 'c' lines in the presence of
NATs.

Dale



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