If mutiple dialogs are enabled for INVITE, and the UASs at two contact
addresses answer the incoming call simultaneously with different SDP
answer, the UAC will create two dialogs with each media sent/received
to/from a different IP peer. The media discription of dialogs caused by
forking are independent.
------------------------------
Dr. LU Wei
Staff Research Member
Infrastructure Technology
IBM China Research Lab
Goix Walter
<[EMAIL PROTECTED]> To:
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Sent by: cc:
[EMAIL PROTECTED] Subject: [Sip-implementors]
SIP/SDP Multiple IP addresses
lumbia.edu
2002-03-05 03:49
Please respond to Goix
Walter
Hi all,
I was wondering if there is any mechanism in SIP to set up a multimedia
session where each media is sent/received from/to a different IP peer
(identifying the same SIP user).
Let's imagine that A wants to establish a multimedia session with B
providing different media (audio and a slide-show for example). B is
registered in 2 different locations (B1 & B2) where B1 only supports
audio and B2 only has the slide-show capability. In this case there will
never be a full 2-media session between A and B, although B's locations
could handle both streams together.
As far as I understand, SDP does support different IP addresses through
a combination of c=/m= lines. That could be fine for a kind of
SIP-enabled media controller that wants to get a media locally and
another one on the device it controls, but I don't see any way of doing
that between independent SIP devices. Do I miss something?
I see some solutions mainly using a B2BUA, but they are all much more
complex and inadequate...Isn't there any lighter alternative?
Thanks for your comments/suggestions.
Regards,
Laurent Walter
_________________________
Laurent-Walter Goix
Telecom Italia Lab - StarSIP
Mobile - Network Intelligence
Via Reiss Romoli 274
I-10148 Torino (Italy)
Tel. +39 011 228 5046
Fax +39 011 228 5069
E-mail [EMAIL PROTECTED]
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