So, I was poking around the web interested in a discussion of the VOIP life cycle; I was really looking for “What ports are used” and so forth, but I stumbled across this very easy-to-read article (although he does drop the F-Bomb once, otherwise it was quite excellent)
It explains the VOIP call life-cycle, including an easy-to-follow graphic (which I’ll attach… a picture says a thousand words after all).
If you’re just getting into VOIP Telephony, this is a great article to help you understand, at a high level, what is connecting where and why.
With the exception that Asterisk is a back to back user agent (B2BUA), this is a pretty good explanation. In a B2BUA, the data/audio/video and bye/OK processes are passed through the User Agent. This allow us to do things like record the calls and make sure that the endpoints remain “reasonably anonymous” from one another.
Yeah… I realized that somewhere in there the PBX was keeping tabs on things… but, for a “high level” view, I found it informative. At least you can see the steps involved.
