Using VoIP with SIP and Asterisk

Asterisk, the Open Source PBX Alternative for SIP Telephony

Open-source software provides an alternative to traditional hardware-based PBX or IP-PBX solutions.  The most widely used is Asterisk.  When combined with a SIP solution, Asterisk can become a cost-effective and comprehensive business communications solution.

What is Asterisk?

Asterisk is an open-source framework for developing communications applications.  With Asterisk, any computer can become a communications server.  Asterisk is sponsored by a unified communications provider, Digium, and is available for free.  Since its release in 1999, it has been tested and improved by a community of thousands of developers.  Asterisk is maintained by Digium and this user community.

What Types of Businesses Asterisk VoIP?

According to the Asterisk website, it is used by small businesses, large businesses, call centers, carriers, and government agencies, across the globe. More than one million Asterisk-based systems are in use, in more than 170 countries and Asterisk is used by many Fortune 1000 companies.

What Skills are Required to Deploy and Manage an Open Source PBX?

Asterisk, like many other open source solutions, is built primarily by developers for developers.  In order to effectively develop your own applications, users need a good knowledge of Linux and script programming as well as networking and telephony.  The solution contains several levels of components that can be customized to develop applications beyond the PBX including, conferencing, call center, and IVR functions.   People without the technical skills to create this level of customization can use pre-packaged solutions built on the platform or work with a systems integrator.  The AsteriskExchange contains a list of pre-built options.

Using Asterisk With SIP Trunking

While the Asterisk platform provides PBX functionality, SIP trunking provides connectivity to the PSTN.  Together the technologies can be used to drastically reduce costs while at the same time providing companies with ultimate flexibility and scalability.  It is important to note that not all SIP VoIP providers are compatible with Asterisk, so companies looking to implement business communications in this manner should be sure that they select a SIP provider that can work with open source PBX solutions.

Asterisk, combined with SIP, is just one example of how communications technologies are moving far beyond the days of complex PBX systems requiring significant capital expense and connecting to traditional carrier-provided PRI lines.  Businesses have more options than ever that allow them to get exactly the services they need with only a modest investment.  As old systems need replacement, we suspect that more and more organizations will embrace this approach.