Asterisk is open–source software iPBX. It runs on the Linux operating system (it is known to work well with Debian, Red–Hat, Fedora, Gentoo, SuSE, Mandrake, and other distributions). Asterisk represents a revolutionary approach to the world of telephony; it brings the concept of open-source to a field that was previously 100% proprietary.

The two major advantages the Asterisk approach are: 1.Significantly lower costs (since the software is free). 2.Rapid development: today thousands of people all over the globe work with Asterisk, many of them contribute to the code.

Asterisk literally evolves and improves from day to day. As a result, by using Asterisk it is possible to build high–end telephony systems for a fraction of the cost incurred when building them in the traditional way.

Asterisk is fully capable of working with IP telephony as well as with POTS (Plain Old Telephony Service) and analog telephones. This new approach to the world of telephony will change the rapidly–expanding iPBX market dramatically in the near future. It will enable smaller companies, using Asterisk–based platforms, to enter this market and offer solutions that compete with those of huge corporations. The new technology will present a problem to companies that carry huge R&D expenses for the development and maintenance of proprietary telephony code.

Asterisk Features
Asterisk is feature–rich and is growing rapidly. Apart from basic capabilities, such as call routing (including DID – direct inbound dialing), call forwarding, music on hold etc., Asterisk can also serve as a conference bridge, send voice mail to email, serve as an IVR (Interactive Voice Response) system, and much more.

Asterisk Usage

Many different types of users, from private and small business implementations to large call centers and service providers, use Asterisk today worldwide. Since Asterisk is open source, it can be implemented as a PBX or iPBX (see below), or be used for a single purpose, such as voice mail or a conference bridge for an existing telephony system.

How did it all begin?

Asterisk was developed by Mark Spencer, who also founded the company Digium which is the main sponsor of Asterisk. Mark started writing Asterisk to save the high costs of telephony for his own business. After he saw the great potential in it, he made Asterisk the main business of his company. Today, Mark and his “bug marshals” still steer the ship.

Asterisk as a Traditional PBX

Asterisk can be used as a PBX for traditional analog telephony. This means you can upgrade an old telephony system without the high cost of changing all of your telephone sets to IP phones. You can enjoy all the features without investing in additional equipment. Asterisk also allows you to gradually start using IP service providers and IP telephone sets in conjunction with the old equipment. In order to use Asterisk as a PBX for traditional telephony, it is necessary to use specific hardware with telephony interfaces, such as channel banks, PCI cards, or small gateways.

Asterisk as an iPBX

Asterisk is fully capable of functioning as an iPBX. The only requirements are: an Asterisk unit (PC); LAN (Local Area Network) and IP telephone sets or IP gateways for connecting analog phones. Asterisk can work with several IP telephony protocols, such as SIP, MGCP, H323, SCCP (Cisco’s proprietary protocol). However, Asterisk is known to have some problems with certain protocols, and it is recommended to work with SIP. Asterisk also works with IAX2 (Inter Asterisk eXchange) protocol, an open source protocol that was written for Asterisk and which handles NAT and firewalls better than SIP and other protocols. Since it works with analog and digital telephony protocols as well as several IP protocols, Asterisk can also be used as a gateway between different protocols.

Astricon

“What other Linux applications have their very own conference?,” - Mark Spencer, Astricon 2004. Astricon is a conference dedicated to Asterisk. The first Astricon took place in Atlanta, in September 2004. Although the organizers expected only 150 participants, approximately 450 people from five continents came to hear about the latest developments in Asterisk, and its future direction. Summary of Astricon 2004. In 2005 there will be two Astricon conferences, one in Europe in May, and one in Atlanta, GA, USA in October.

The Future of Asterisk

Asterisk is growing at an extraordinary rate. VoIP guru Jeff Pulver states: “They are developing a sophisticated PBX on a PC with the (capability) of a $100,000 PBX…It will be a world class PBX that runs on Linux. You can have a PBX for the cost of a PC. Jon ‘Maddog’ Hall, president of Linux International, states: “I predict that over next three years, VoIP using an open-source solution, such as Asterisk; will generate more business than the entire Linux marketplace today.”

According to a recent report published by the Eastern Management Group, Asterisk is the most popular open source telephony software by far, holding 85% market share. In addition, the report finds that 18% of North American telephony installations now include open source components.

Two Leading Reasons for Choosing Open Source

The two main reasons for choosing open source, provided by respondents to the survey conducted as a basis to the report, were:

1.The minimal investment needed to create an open-source telephony system (open source PBXs typically cost ~40% less than conventional telephone systems)
2.The higher flexibility of the systems, as compared to proprietary, for integrating software applications More Things to Look For...

We'd like to expand on these points, in an effort to provide tools for choosing the open source system that suits your needs. Keep the following in mind when reviewing your options:

1. Openness

One of the strengths of open source is the fact that the customer is less dependent on the vendor, that is, after the solution is implemented he has a variety of partners to work with for support, maintenance and upgrades. It is important to make sure that the system is not linked too tightly to a specific vendor. Some systems are based on open source, or have open source components, but as a complete system are “locked” to the specific vendor for any practical purpose. In today's economical atmosphere it is extremely important to know that even if the vendor goes through significant changes, the customer will still be able to get appropriate support from another company dealing with such systems.

2. "Parents"

Without contradicting the previous point, the customer should verify that the system they purchase has a good reliable vendor behind it. Since open source telephony, lead by Asterisk, makes it very simple to create an IP PBX, many integrators are tempted to do it all by themselves. Such "home-made" units may be well built, but they also may be unstable and hard to maintain for the long run. In this respect it is better to get a system that was produced by a manufacturer of open source IP PBX rather than a system built by the integrator.

3. Total Cost of Ownership

One of the most important drivers for open source telephony is the attractive price. However, it is important to do the right calculation and see what the total cost will be. Factors like additional network components (replacing a router, purchasing a new switch), maintenance costs and the like should be taken into account. One of the ways to significantly reduce the system's cost is to maximize usage of existing infrastructure such as wiring and handsets. This can have a significant effect on the overhaul system cost.

4. Good Integration Partner

It is important in any telephony system, but since open source systems are more flexible a good integrator will know how to take advantage of this flexibility and optimize the system.

5. Stability

Since there is a wide range of open source based offerings in the market today, and since the entry barrier for vendors is much lower with these new technologies than it was in the proprietary world, the customer should check references and talk to other end-users using the proposed system to make sure the system is right for him.

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