[SIPForum-discussion] Calls vs sessions vs dialogs vs transactions

[Barry Demchak]

Hi, all --

Sorry for such an elementary question. I'm trying to model some 
aspects of SIP, and I'm not quite sure how calls, sessions, and 
dialogs relate. (Dialogs are easy ... they're the context for 
transactions ... and can support a number of them over time.)

I have definitely read RFP3261, but it's not quite helpful here. I 
have also visited the (excellent) tech-info site.

Here's what I'm having trouble with:

Is a call the same as a session??

Apparently a session can have numerous dialogs ... when can that 
happen, and what does it mean?

Clearly, setting up a dialog has a formal process. Is there a process 
for constructing a session or a call ... separate from setting up a dialog??

Thanks.