VoIP Application Layer 1: The Packet Infrastructure

Thinking of creating your own VoIP application Part II.
Layer 1: The Packet Infrastructure

Let's say I am Superman and I have X-ray vision. My goal is to look at the inner-workings of a VoIP application or clients like Skype, Yahoo Messenger and Five9 Virtual Contact Center (VCC) Agent.

Like Superman, my goal is to "see-through" this VoIP application because I need to investigate on something. Apparently, Lex Luthor, being a rich genius that he is, has managed to create his own secure VoIP client. Lex Luthor is using this VoIP client application to make calls to his henchmen. So its up to me to investigate on this, retrieve evidence and prove to that he is the mastermind.

If I was Superman, all I need to do is use my X-ray vision to see-through the VoIP application Lex Luthor is using. I will immediately see hundreds of lines of programming codes, specifically variables, commands, and on the networking side, what communication protocols and their corresponding ports this application is using to communicate over the Internet. Now that's interesting.

Luckily, we do not need to be a man of steel or someone who wears blue and red tights and fly around the city saving people and still look cool in the process. Thank goodness for protocol analyzers. It is the X-ray vision of us guys in the voice and data networking field.

Wireshark, (known as Ethereal from its early days) is one of the leading protocol analyzers out there, and its free. If you need to investigate the inner-workings of an application connected to a network, Wireshark is your answer. It is slowly becoming the tool of choice for network sniffers and VoIP phreakers, black hat or white hat. There's tons of things you can do with Wireshark once you have it installed and running on your network, but that is beyond the topic of this post.

For this post, I will refer and use Wireshark extensively to show to you what networking protocols and ports Five9 Agent VCC is using. Five9 Agent VCC is a VoIP client used by Call Center Agents around the globe in making and receiving calls. Five9 VCC Agent utilizes a Softphone feature, the dial pad and other telephone features are on the screen, just push the buttons you need. All you need is a reliable Internet connection, a USB headset with microphone and an account with Five9, and that's it.

(To be continued on next post)