What is Asterisk? A Backgrounder...

“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.” – VoIP guru Jeff Pulver

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. For more information about Asterisk features see www.voip-info.org .

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.”

by Eran Gal – CEO, Xorcom Ltd. - Asterisk-based PBX Solutions