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Thank You

I remember the first time I tried to learn VOIP.

I downloaded a variant ¬†of Asterisk and ran it on my Windows PC. Yeah, that’s right. I installed Asterisk on Windows. I was young and had no clue what I was doing.

Everything sort of worked. Well, until it didn’t. ūüôĀ

I had no clue how to troubleshoot the SIP messages. Registration? What’s that? INVITE? Why do I need an INVITE for something? Do I send an RSVP back to the server when it INVITES me? Ok.. bad joke.

I quickly became frustrated with the whole concept. I ended up deleting Asterisk from my Windows machine and vowed to never touch VOIP again.

That lasted for about a week. 

I became obsessed with learning VOIP. I spent hours of my day reading through RFC documentation.  I would draw out call flows with a pen on paper until I understood what was going on.  After a few months I decided to install Asterisk again. Two days later I had a full blown IP PBX installed at home. I had phones in every room. I understood a lot about SIP and eventually moved from working on analog and digital phone systems into 100% IP.

I learned the hard way. Don’t take the path I did.

I created a course that covers the basics of SIP.  This course is easy to follow and will give you the proper foundation to understand SIP, SDP and how RTP flows between endpoints.

I also cover common troubleshooting scenarios such as why one way audio and much more.

There are other courses out there that sell for nearly $400. I know that’s a significant investment for those just starting out in IT or telecom.

Don’t worry I have your back.¬†

I decided that this course needs to be affordable. Initially I planned to offer this for $99. I thought about this price for a few weeks. I was ready to set $99 as the price, then something came over me. I realized that $99 is still too much for this knowledge.

Eventually I settled on the low cost of $40. This course has a little over three hours of content and covers the following topics.

  • What is SIP and the RFCs that it is defined in.
  • The different types of SIP clients and servers
  • The structure of SIP messages
  • Overview of SIP response codes
  • The structure of the SIP¬†URI
  • Overview of SIP¬†headers and their purpose
  • How the Session Description Protocol (SDP) works
  • How SIP allows mobility through call forking, REFER requests and Diversions
  • The details of SIP transactions and Dialogs
  • How SIP proxies route requests (We discuss stateful and sateless proxies)
  • The SIP Trapezoid model
  • How SIP Registration works.
  • How SIP Authentication works. We dive into how the MD5 hash is created.
  • What challenges SIP faces with NAT and how to overcome them.
  • An overview of the Real Time Protocol – AKA¬†RTP

Sounds like a deal for $40 doesn’t it? ¬†Normally I would sell this course to you for that price, but you did as I asked. I thank you for that.

By signing up for our mailing list it shows that you are interested in advancing your career. I know learning VOIP and SIP has enabled me to earn a $100K+ salary. Do you want that?

Learning a specialized IT skill can also allow you to become a respected industry expert with many career opportunities. I want you to thrive in your career. No more help desk roles. No more low level tech support.  Only the best for you my friend.

Are you ready to take your career to the next level? If you are, click the below link. You will be redirected to with a special coupon code in the link.¬†When you get to Udemy, click on “Take this course“.

SIP Training


I’ll see you in class!

Keith Croxford is an expert in VOIP, Telecom and SIP.
Keith Croxford is an expert in VOIP, Telecom and SIP.



You rock!