[SIPForum-discussion] Difference between DIALOG, SESSION and TRANSACTION

mishra.abhishek at wipro.com mishra.abhishek at wipro.com
Fri Aug 17 12:55:37 UTC 2007

Hi Lokesh,
A transaction refers to a fundamental unit of message exchange. It
basically includes a request-response cycle.
 Dialog represents a peer-to-peer relationship between two user
agents.It is usually created through generation of "non-failure"
responses to request. e.g.
UAC                      UAS
  ---INVITE (a)--->
<--100 Trying (b)-----
<---200 OK (c)--------
---ACK (d)--------------->
----200OK (f)------------------>
In the example 1, (a) to (c) are one transaction. (d) is second
transaction and (e)& (f) constitute third transaction. 
Together, these three transaction constitute one dialog
UAC                        UAS
      -----INVITE (g)----->
      <---100 Trying-(h)----
       <--486 Busy (i)------
       ---ACK (j)------------->
In the example-2, the messages from (g) to (j) constitute one
transaction. This is a "no-dialog" scenario.
A session refers to the exchange of media between two or more Endpoints.
Also, there can be dialogs without SIP sessions.
Hope that this helps.
thanks & regards
Abhishek Mishra
Wipro Tech
Tower-8, 1st Floor, C-wing
Electronics City Campus

From: discussion-bounces at sipforum.org
[mailto:discussion-bounces at sipforum.org] On Behalf Of Lokesh Agrawal
Sent: Friday, August 17, 2007 5:29 PM
Subject: [SIPForum-discussion] Difference between DIALOG,SESSION and

Hi All,

Can Any one tell me difference between DIALOG, SESSION and TRANSACTION.
Please tell in detail with an example.

Thanks and Regards
Lokesh Agrawal

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