My tool of choice for dissecting call flows is Wireshark. They make those calls and then wade through SIP messages to understand exactly what happened behind the curtain. While seeing those things from a user’s standpoint is important, I get them down and dirty with the protocol itself. They install a SIP soft phone to make calls, change their presence status, send instant messages, and invoke call features such as conference, transfer, and hold. One of the reasons why they leave class with more than just a “book learning” is that we put SIP to work. My students learn as much as anyone could be expected to learn about SIP in such a short period of time. We start with the basics of SIP before going through every message type, all the important responses, call flows, media, security, and even touch on cloud communications. It’s only a two and a half day course, but it’s a very intense two and a half days. I am talking about the SIP class that I teach every few months. While it’s not the same as tenure at an Ivy League university, I am able to develop curriculum and impart knowledge to willing pupils. Thankfully, I do have an opportunity to periodically stand in front of a bunch of students and play professor. Still, while I’ve lost interest in being a DJ, I continue to feel the call to teach.

patent office along with Thomas Edison and the inventor of the Whoopee Cushion.

I’ve traveled all around the world on the company dime. I worked on a number of really cool projects. For better or worse, I ended up being a software developer at a telecommunications company. When I was younger I had two careers in mind – a college professor or a radio disc jockey.

Wireshark filter sip invite