[SIPForum-discussion] Which layer adds branch parameter

[Vijay Badola]

Hi Vijay,


1.       UAC or Stateless/ Statefull proxies, all the are the transaction users and considered as the fourth layer as per SIP specifications.

2.       Generally transaction user  or transaction layer(third layer) is used to add branch parameter.

3.       Most of the sip stacks add the branch parameter in SIP message itself and provide an interface to transaction user, so that UAC or Proxy can also add branch parameter.

4.       If some transaction user adds the branch parameter then it has greater precedence over transaction layer and only transaction user's branch will be used.

5.       If transaction user does not add branch parameter, then it is the responsibility of transaction layer to add it.
Now if some application (UAC/UAS/Proxy etc. ) wants to  add branch parameter ( for example transaction user want to send special string sequence in branch) then it will use interface provided by sip stack.

Regards,
Vijay Badola




From: discussion-bounces at sipforum.org [mailto:discussion-bounces at sipforum.org] On Behalf Of Vijay Kumar
Sent: Monday, January 07, 2013 10:00 PM
To: discussion at sipforum.org
Subject: [SIPForum-discussion] Which layer adds branch parameter

Hello all
Please help me in understanding "Which SIP layer adds branch parameter in UAC/Stateless/Statfull proxies"
Thanks in advance
Regards
Vijay

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