Welcome back to the Transparent Telephony series. If you're a new reader, you may want to start at the beginning: Part 1 - An Introduction.

In the previous installment, we walked through installing Asterisk. In this article, we'll be picking up where we left off and configuring Asterisk to make and receive phone calls using VoIP!

Specifically, we'll:

Welcome back to the Transparent Telephony series. If you're new, you may want to check out part 1 here: Transparent Telephony - Part 1 - An Introduction.

This series is designed for technical people, programmers, and just general enthusiasts who want to learn: how telephony works, how to setup your own phone server (PBX), how to write telephony applications, and how to reduce your phone expenses. There are tons of neat things you can do with telephony knowledge, so keep reading!

This article will walk you through installing Asterisk on your CentOS or Ubuntu server. If you are going to install on a virtual machine to follow along, I recommend using VirtualBox, as everything should work out of the box. Certain virtual machine programs like Xen have kernel issues which makes installing Asterisk difficult. Also, never ever use Asterisk in production on a virtual machine! You'll have timing issues (this will be explained later in the series).

So you've probably heard the word telephony thrown around from time to time. Maybe you were hanging out in a certain IRC channel, wanted to root your cell phone, or maybe, just maybe, you were actually interested in doing something cool with your computers and phones.

This article is the first of a series. I'm going to try my best to explain what telephony is, how it works, and how to write cool programs that integrate voice and data. Telephony is a huge market, and used everywhere (think cell phones). We are living in a time when telephony is casual, common, and popular. While being so huge, it often astounds me to think of how few programmers and tech people ever get around to learning about it, or playing with it. There are very few telephony programmers, and even less proper documentation. My hopes are that these articles will give you a solid foundation in telephony and inspire you to play around with it on your own, and do cool things.

Now that we've got the basics out of the way, let's get down to business...