FreeSWITCH, a scalable open source cross-platform telephony platform, is designed to route and interconnect popular communication protocols using audio, video, text or any other form of media.

 

Created in 2006, FreeSWITCH was a response to proprietary commercial solutions and offered a range of free tools to foster the development of new telephony applications.

 

Today, many developers and users contribute to the project on a daily basis.

I had a chance recently to catch up with Anthony Minessale, creator and lead developer behind the FreeSWITCH open source telephony project,  to find out more about the project, the company and what they have planned.

 

FreeSWITCH was started in 2006 by myself, Anthony Minessale, after spending several years doing development for the Asterisk PBX (News - Alert) project. I was quickly joined by two other Asterisk developers: Brian K. West and Michael Jerris and with their help was able to build FreeSWITCH from the ground up. It is not a fork of Asterisk (News - Alert) or of any other project, but is a completely original soft-switch, written from scratch.


Why write a new communications platform from scratch? Quite simply because there wasn't an existing solution that could do what Anthony envisioned for FreeSWITCH. In fact, to the best of our knowledge, there still isn't anything that can do what FreeSWITCH can do, even in commercial offerings.

 

FreeSWITCH is a complete communications platform upon which virtually any communications solution can be built - voice, text chat, video - anything that exchanges media. It is scalable and cross-platform. Most importantly, it is open source, released under the business-friendly Mozilla Public License 1.1. 

One of the key design philosophies of FreeSWITCH is that of modularity. By being modular FreeSWITCH can scale up to handle many thousands of calls on a single machine or it can scale down to act as the media engine for a single endpoint. (The FreeSWITCH Communicator soft-phone project is a good example of this.) Achieving modularity requires a disciplined approach to software engineering. One aspect of that approach is not re-inventing the proverbial wheel. FreeSWITCH therefore relies on 3rd-party software libraries to provide necessary - but not core - functionality. The prime example of this is with the Sofia SIP stack. The Sofia SIP stack is developed and maintained by Nokia (News - Alert). By letting the Nokia engineers develop and maintain the SIP stack the FreeSWITCH developers can focus on what they do best, namely developing the core functionality of FreeSWITCH.

The net result of these design decisions and developmental disciple is that FreeSWITCH is powerful, flexible, and stable. It truly is a revolutionary piece of software engineering. 

 

In several ways. Perhaps the most obvious is that FreeSWITCH is 'free' in the sense that it is open source, freely downloadable and usable under the MPL. Anyone with even a somewhat modern computer may download and use it however they wish. Furthermore, FreeSWITCH supports many zero-cost audio codecs: CELT, Speex, Broadvoice, SILK, G.722, and others. With the requisite hardware and networking infrastructure an enterprising developer (or team) can build a commercial-grade telephony solution with zero software licensing costs and zero patent royalties. FreeSWITCH is the unifying agent in a FLOSS VoIP environment.

Another aspect of 'free' is software 'freedom.' There are different kinds of freedoms when it comes to FOSS licensing. I chose to eschew a 'strong copyleft' license (such as the GPL) in order to prevent a user being forced into releasing his or her own FreeSWITCH-based project under a similar license. For FreeSWITCH to be truly 'free' (in the sense that we don't want to force people to choose a particular software license) it was necessary to choose a more liberal license that places fewer restrictions on the end user. FreeSWITCH aims to be as unrestrictive as reasonably possible with respect to software licensing.

 

Back in April, FreeSWITCH announced the release of version 1.0.6 - can you talk about the enhancements added to this latest release and their benefits?

FreeSWITCH 1.0.6 saw the introduction of many features.

Two new codecs were added shortly after their respective open source releases: SILK (from Skype (News - Alert)) and the BroadVoice family of codecs (BV16 and BV32). Because of FreeSWITCH's modular design, these codecs were built very quickly - in as few as 90 minutes after the code became available to the FreeSWITCH developers!

An additional feature that is relevant to many businesses is the availability of the g.729 audio codec. While not 'free' it is reasonably priced and reduces bandwidth considerably over the ubiquitous (but aging) g.711 codec.

We also introduced the Broadsoft method of shared call appearance (SCA) in this release. Most VoIP veterans are aware of the challenges inherent in a VoIP-based PBX, especially when trying to emulate the behavior of the traditional key system. The Broadsoft SCA method relieves some of those challenges by giving disparate telephone vendors a specific standard to perform shared call appearance in a VoIP environment.

Other new features include a valet call parking application, the initial version of mod_skinny (for Cisco (News - Alert) SCCP phones), and a provisional version of a new H.323 module (mod_h323).

Sangoma is a strong supporter of the FreeSWITCH project and recently also announced its support for the powerful PSTN interface module, FreeTDM - what will Sangoma contribute specifically for this?

Sangoma is contributing significant development resources to the FreeTDM project. In addition to software engineers investing numerous man-hours into programming, Sangoma has also made TDM lab facilities available for testing FreeSWITCH and FreeTDM.   Sangoma has also been a proud sponsor of 6 consecutive ClueCon telephony conferences.

 

You also have an upcoming book - can you talk a little about that - what is the book about and where can readers purchase it?

Last year Packt Publishing approached me about the possibility of producing an introductory book on FreeSWITCH. I accepted and invited Darren Schreiber and Michael S. Collins to co-author large portions of the material. All three of us have spent many hours poring over the text. The finishing touches are now being put on the book which is tentatively scheduled to be available in July of this year. The exact title and cover art are still being finalized, but the book has been announced: http://www.packtpub.com/freeswitch-1-0-5-build-robust-high-performance-telephony-systems/book

You will also be participating at the upcoming ClueCon Telephony Developers Conference which will take place the first week of August at Trump International Hotel & Tower, Chicago, can you provide some of the highlights attendees can look forward to?

ClueCon is the premier annual event for VoIP developers and enthusiasts. We have an excellent mix of sponsors, speakers, and conference attendees. ClueCon avoids the typical gauntlet of vendor booths that are common to many trade shows. Instead, it lets the attendees focus on building relationships - business and personal - by encouraging developers, business administrators, and even end users to interact with one another.

 

Attendees this year will come from around the world - Europe, Africa, Australia, and the Americas. The wide range of personalities and backgrounds makes for a lively event.

This year ClueCon will be giving away two iPads and a 13' Macbook Pro. Like we did last year, the sponsors' logos will be laser-engraved on the back of the devices. The laptop we gave away last year was beautiful!

As an added incentive, our own Brian K. West has agreed to shave his head at ClueCon if we have 200 registered attendees by July 4th! We definitely want to see that happen, so all are encouraged to sign up right away. Details are available at http://www.cluecon.com.

Any other interesting or upcoming announcements we should be on the look out for?

We may have a surprise or 2 to announce this summer at ClueCon! What we can tell you is that we plan to release FreeSWITCH 1.2 very soon.  I suggest everyone follow us on twitter or come visit us on IRC at irc.freenode.net #freeswitch.