El Miércoles, 20 de Enero de 2010, Couret Tabt escribió:
> Dear folks,
> 
> I have a question what is different, UPDATE and reINVITE?
> In RFC3311(5.1.) it is written as follows:
> 
> Although UPDATE can be used on confirmed
>    dialogs, it is RECOMMENDED that a re-INVITE be used instead.  This is
>    because an UPDATE needs to be answered immediately, ruling out the
>    possibility of user approval.  Such approval will frequently be
>    needed, and is possible with a re-INVITE.
> 
> But I can NOT think out a good example flow.
> If you think out it, please let me know.

A re-INVITE requires the dialog established prior to take place, while an 
UPDATE could occur within the dialog establishment (between INVITE and 200 OK 
I mean) to change SDP parameters and so.

Also, an UPDATE is inmediately replied by the SIP core of the remote endpoint. 
In the other hand, re-INVITE could require, in some cases, authorization of 
the user (human user). For example, alice is in an audio call with bob, and 
after some minutes of conversation bob decides to add video to the session. 
This is acomplished by sending a re-INVITE with audio&video SDP. Alice's phone 
receives such re-INVITE and ask the human user to accept or reject the video 
session.


-- 
Iñaki Baz Castillo <[email protected]>

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