Monthly Archives: May 2014

Understanding SIP Registration

Let’s start at the very beginning a very good place to start when you read you begin with A B C when you sing you begin with Do Re Mi I have always loved musicals and Rogers and Hammerstein’s “The Sound of Music” is high on my list of favorites. Sure, it’s corny and far […]

Eating SIP One Bite at a Time

Question. How do you eat an elephant? Answer. One bite at a time. My piano teacher had those words taped to the wall of his studio and they are as applicable to a large communications project as they are to learning a new piece of music.   You will wind up completely frustrated if you attempt […]

The Intelligent Guide to Choosing SIP

I am coming up to the one year anniversary of this blog and so I decided to do something a little different.  Instead of writing two or three pages about a particular SIP request or response message, I want to give you something a little bigger.  In this case, 26 pages bigger. Since 2012, I […]

Implementing Presence With SIP

Are you familiar with busy lamps on telephones? For many years, they were the only way you could “see” the telephone status of a coworker. For example, let’s say that Andrew is the administrative assistant to Debbie and as part of his job, Andrew needs to know when Debbie is on and off the phone. […]

Finding and Fixing SIP and VoIP Problems

With the exception of perhaps Frank Sinatra’s voice, nothing in life is perfect. This is especially true for those of us in the software business. Of course, if the developers got it right the very first time, people like me would be quickly out of work. My job depends upon problems to fix and next […]

9-1-1 and SIP

Have you ever had the need to dial 9-1-1? Unfortunately, I have. It was just one time, but one time is enough for me. I won’t bother you with the details, but minutes after the call was answered, a swarm of paramedics had converged on my house and although the emergency was resolved seconds prior […]

Untethering the User From the Device with SIP

Those of you (like me) of “a certain age” might remember that your first work telephone was probably an analog 2500 set that looked a lot like this. It was fine for making and receiving calls, but that was about it.  It had no Bluetooth integration for a headset or a display for caller ID. […]

Understanding SIP CANCEL

As I have said on a number of occasions, I occasionally teach a two and half day SIP class. While that’s hardly enough time to become a SIP expert, my students always leave with more than enough knowledge to make educated decisions in regards to SIP endpoints, applications, and trunks. Although some may never again […]

Avaya Session Manager Lessons Learned and Relearned

I attended the International Avaya Users Group Converge2014 in Dallas, Texas last week.  This has been an annual event for me for many years and despite the non-stop days and nearly sleepless nights, it’s something I look forward to very much.  Not only do I get a chance to stand before like-minded people and pontificate […]

A Toll Fraud Primer

I’ve written a number of articles about the how to create a secure SIP infrastructure, but I haven’t really spent much time on what happens if you don’t.  There are lots of nasty people out there who are determined to steal money or information from anyone foolish enough to leave the doors to their business […]