[SIPForum-discussion] About branch and tag id in sip header

[zxh1336 at sina.com]

To: all
Thanks fo dicussion the topic .
I think the content in the RFC3216 is useful
 
#################################
When the UAC creates a request, it MUST insert a Via into that
   request.  The protocol name and protocol version in the header field
   MUST be SIP and 2.0, respectively.  The Via header field value MUST
   contain a branch parameter.  This parameter is used to identify the
   transaction created by that request.  This parameter is used by both
   the client and the server.
   The branch parameter value MUST be unique across space and time for
   all requests sent by the UA.  The exceptions to this rule are CANCEL
   and ACK for non-2xx responses.  As discussed below, a CANCEL request
   will have the same value of the branch parameter as the request it
   cancels.  As discussed in Section 17.1.1.3, an ACK for a non-2xx
   response will also have the same branch ID as the INVITE whose
   response it acknowledges.
############################################################




----- Original Message -----
From:Gopalarathnam Sambasivan 
To:rama kumar 
Subject:Re: [SIPForum-discussion] About branch and tag id in sip header
Date:07-08-17 23:25:55


Just to add,
Call-ID - For a dialog,  i.e., INVITE, PRACK, ACK, BYE all have same call-ID.
Via header branch parameter - per transaction.
i.e.,  a INVITE, its 100 Trying, 180 Ringing, its 200 OK is same (1)
ACK is different(2), PRACK and its 200 OK is different(3), BYE is different (4) all of which 
can be for the same dialog.
 
Please Read RFC3261 - for more info.

 
On 8/17/07, rama kumar <ramakumard at yahoo.co.in> wrote: 

Call-ID header is used to identify the dialog and it is unique to that dialog.
&nbsp;
Branch Id is a parameter which is a part of Via Header. This is used to identify the perticular&nbsp;transaction created by the request.
&nbsp;
Thanks,
Ramakumar D


Asha Pillai <asha.g.pillai at gmail.com> wrote:
I just want to know wat is the basic difference between tah branch id and call id.

also in rfc its written that during registration between UAC and registrar always call id is unique for that combination.Is it like that for only REGISTER message
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