[SIPForum-discussion] [spam] RE: A and B with G.711

Underwood, Rosa rosa.m.underwood at verizon.com
Fri May 15 13:20:26 UTC 2009

   Taken from RFC 4028 section 7
   A re-INVITE generated to refresh the session is a normal re-INVITE,
   and an UPDATE generated to refresh a session is a normal UPDATE.  If
   a UAC knows that its peer supports the UPDATE method, it is
   RECOMMENDED that UPDATE be used instead of a re-INVITE.  A UA can
   make this determination if it has seen an Allow header field from its
   peer with the value 'UPDATE', or through a mid-dialog OPTIONS
   request.  It is RECOMMENDED that the UPDATE request not contain an
   offer [4], but a re-INVITE SHOULD contain one, even if the details of
   the session have not changed.  In that case, the offer MUST indicate
   that it has not changed.  In the case of SDP, this is accomplished by
   including the same value for the origin field as did previous SDP
   messages to its peer.  The same is true for an answer exchanged as a
   result of a session refresh request; if it has not changed, that MUST
   be indicated.


From: Vivek Batra [mailto:Vivek.Batra at matrixtelesol.com] 
Sent: Thursday, May 14, 2009 11:59 PM
To: Underwood, Rosa; 'Jyothi Laxmish'; discussion at sipforum.org
Subject: [spam] RE: [SIPForum-discussion] A and B with G.711

In confirm dialog, you can negotiate SDP using Re-INVITE however you can
again negotiate the SDP in early dialog using UPDATE.


From: discussion-bounces at sipforum.org
[mailto:discussion-bounces at sipforum.org] On Behalf Of Underwood, Rosa
Sent: Friday, May 15, 2009 3:12 AM
To: Jyothi Laxmish; discussion at sipforum.org
Subject: Re: [SIPForum-discussion] A and B with G.711

I believe a reINVITE should be used since the change will be during an
established dialog.    RFC 3261 should provide guidance. 

From: discussion-bounces at sipforum.org
[mailto:discussion-bounces at sipforum.org] On Behalf Of Jyothi Laxmish
Sent: Thursday, May 14, 2009 6:15 AM
To: discussion at sipforum.org
Subject: [SIPForum-discussion] A and B with G.711

Hi all


    Suppose A and B are in conversation stage with g.711 codec.

     A want to change his codec with g.729 ( any other also)   which B
supports. In this

   Scenario how A has to communicate with B  in Sip. Whether UPDATE can
be used? If yes how?







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