Problem solve Get help with specific problems with your technologies, process and projects.

Asterisk: Open source VoIP/PBX for the enterprise

Learn the pros and cons of using Asterisk, an open source hybrid Voice over IP (VoIP) and Private Branch Exchange (PBX) solution. This tip provides a list of features and best practices, and addresses common misconceptions so you'll be prepared when your customers ask about it.

Learn the pros and cons of using Asterisk, an open source hybrid Voice over IP (VoIP) and Private Branch Exchange (PBX) solution. This tip, courtesy of, provides a list of features and best practices, and addresses common misconceptions so you'll be prepared when your customers ask about it.

Asterisk continues its campaign as a cost-effective open source hybrid Voice over IP (VoIP) and Private Branch Exchange (PBX) solutions provider from software and hardware products to services and support. Digium -- Asterisk's parent company -- boasts doubled sales over the past few years, currently earns more than $10 million annually, and sees downloads numbering upward of a thousand per day. Venture capital firm Matrix Partners, an open source software investor, recently plunked another $13.8 million in Digium's already brimming coffers to expand development for Asterisk business-class capability and create another stronghold in the open source marketplace.

There are pros and cons to every open source solution, especially in the enterprise landscape, and Asterisk has a full range of features, functionality and friendliness to support a variety of needs and circumstances. This article highlights a few of those high points and lends perspective to the level of maturity Asterisk has achieved.

Why use Asterisk?

A common misconception about Asterisk configuration and operation is that it requires adept Linux expertise. Digium offers service and support teams to provide technical hand-holding through the entire process, however, making Asterisk accessible to any enterprise environment. Digium covers all areas, from complete PBX solutions to specialty Asterisk add-in cards (also produced by Digium) and troubleshooting technical support.

Cost-savings benefits for this open source solution are not as great for enterprises with existing PBX/VoIP infrastructures, but they are definitely a factor for first-time buyers of the technology. Asterisk uses Linux, which is known to work and play well with legacy x86 Intel/AMD hardware (among others) -- meaning a commodity Asterisk server can be composed of reissued market parts or in-house components. This provides an excellent low-cost alternative to finished PBX products that can range in the five to tens of thousands of dollars. Comparatively, a simple whitebox solution begins at $1,000 and goes up according to case-by-case configuration.

Consolidation is another key benefit, where the voicemail and fax server are combined into a single server with massive amounts of accessible storage space. A number of graphical user interfaces exist for Asterisk management purposes. These range from configuration interfaces such as Intuitive Voice Technology for small to midsized businesses, to control panels such as Third Lane Technologies for full-fledged service providers.

Clearly, Digium is not the only company successfully building upon its own Asterisk solution -- a mushrooming contingent of vendors also provides complete systems such as Phonality's IP PBXtra system for custom client configurations with enterprise-class features starting under $1,000. Phonality even throws in a Web-enabled control panel to ease daily management tasks.

Asterisk best practices

Asterisk arrives in two forms: a free open source package and a retail business-class solution. The business-class solution builds upon the free version and provides additional security and voice features for enterprise users of Asterisk products; it also includes proprietary driver support otherwise separate from the free variant. Choose one according to the cost of contracting or hiring a support team for in-house system integration and upkeep, where such help is not already provided internally.

A distinct advantage of the business-class edition is the addition of a firewall module called "net-sec," which dynamically opens and shuts firewall ports as needed, providing a high degree of security. It also simplifies deployment with the inclusion of a customized Linux platform tailor-made for enterprises using a single CD image.

Make product and service choices according to individual business needs: Where there is a lack of in-house Linux support, lean on Digium or other third-party vendors that provide telephone-based assistance. The latest business edition contains a variety of new features, including the LumenVox Speech Engine and Cepstral Text-to-Speech System, some of which may require additional training for usage and best practices -- again, Digium has it covered with its own training services.

Lack of vendor lock-in, both in terms of the management consoles and complete solutions, gives Asterisk deployment additional flexibility and choices for potential enterprise customers. System integrators and administrators can wade through a number of management console options to find the right one to satisfy the most requirements for any particular business.

Ultimately, the freedom of choice with Asterisk is the most empowering benefit of all. Asterisk is at the forefront of successful open source options worthy of enterprise deployment, and it is modular enough to scale to satisfy many requirements.

About the author
Justin Korelc is a longtime Linux hacker and system administrator who concentrates on hardware and software security, virtualization and high-performance Linux systems. He contributes regular articles in several areas of network deployment, server management and information security, using mostly open source solutions.

This tip originally appeared on

Dig Deeper on Voice and unified communications

Join the conversation

1 comment

Send me notifications when other members comment.

Please create a username to comment.

I tried to work on research which is design and implementation of voip pbx phone system using open source software but unable to to carry out the project which was to be summited a week from now...Any help will be appreciated...Thks