Asterisk bills itself as "the world's leading open source PBX, telephony engine, and telephony applications toolkit." You can use it as the basis of a fully featured, enterprise-class phone system in your organization. Like any complex piece of software, you'll have some work to do coming to grips with what it can do and how to set it up. One ideal way to get up to speed fast is by going on a three day Asterisk Fast Start training course offered by Digium, the company that sponsors the Asterisk open source project.
The Fast Start course assumes no previous knowledge of Linux - the platform on which Asterisk runs - or any knowledge of corporate telephony. Having said that, the course is designed for people who are responsible for corporate telephony, who understand IP networking and who would be familiar with the network topology in their organization. A rudimentary knowledge of some basic Linux commands and tools like ls, cp, and gedit or nano is also pretty much essential. The course takes place in a training room equipped with a PC freshly installed with CentOS (a Red Hat derivative) for each student, all connected to a server which simulates various external lines, exchanges and situations. It consists of a combination of lectures and roll-up-the-sleeves practical lab sessions.
The first part of the course deals with how phones work and the different types of analog and digital trunks that are available, outlines the concept of a codec and introduces various types, and explains what open source software is. Pretty basic stuff, which anyone attending thinking of installing Asterisk should probably know already. Then it's on to downloading the source code for the various components needed to run asterisk, and compiling and installing the software onto the CentOS PCs.
To make it more interesting, the rest of the course is built around a scenario: a small baker's shop on the East coast that needs internal phones connecting the kitchen and front counter, a line out to make local calls, VoIP capability to make cheap toll calls, and a "direct" connection to another baker's shop which also uses Asterisk on the West coast. The remaining three days revolve around connecting phones and trunk lines to the Asterisk box and configuring the software to create a solution which would suit this scenario, and adding features like voice mail and a dial-able company directory.
This scenario is actually very useful because it crystallizes what Asterisk can do, and it only takes a modicum of imagination to realize that the scenario could easily be extended to a much larger organization with many extensions, a combination of conventional and IP telephony, and "direct" connections to branch offices. It's also quite ambitious: a student with no previous knowledge of Asterisk would have no idea how to go about building this at the start, so to achieve this in three days is a big task. That means there's a lot of ground to cover, and not much time to cover it in.
The most important thing to understand about the course it this: it is intended to be an introduction to Asterisk, and it won't make you an expert in three days. The only way to get through the labs is to follow the written instructions and get help from the instructor when things don't work first time which inevitably they won't. At the end of the course you may have built a working phone system, but going back to the office and trying to do the same thing again without an instructor on hand to help trouble shoot could take weeks.
And, to be fair, you can't expect more from three days of intensive training. Digium recommends that after attending the Fast Start course students should play around with the system for six months or so before attending an advanced course or trying to implement a working system for themselves. In this respect learning to use Asterisk is no different from training to be a network or system admin: you certainly can't learn it in three days, and you need plenty of day-to-day on-the-job experience to get thoroughly proficient at it.
But what the Fast Start course does do is provide exactly what the name implies: a quick start into the world of Asterisk that could save you hours of frustration trying to get to grips with the software. It can help you evaluate whether it is capable of providing the telephony service that you need, and whether it would be practical to implement it or maintain it yourself. If you are interested in exploring Asterisk as a possible telephony solution the course is definitely worth considering.
The Asterisk Fast Start course is available in the USA, UK, Europe and Australia. The course costs $1995 / £1299 / 1600 / AU$3100, including training, course notes and workbook, refreshments , and a VoIP phone and two PC interface cards to allow students to experiment with what they have learned or go through the course again in their own time using after the course has finished.