Open Source Compliance

All Howler software and hardware products are GPLv2 compliant and licensed to be commercially deployed on Asterisk®, Freeswitch and Callweaver VoIP telephony platforms.

Open Source Essential Information
When we originally developed our G.729 Howlet, it was pointed out to us that our implementation and distribution methods might potentially be in violation of the General Public License Version 2 (GPLv2).

In a genuinely open spirit of transparency and co-operation, we completely re-architected our product structure to address these concerns. Specifically in relation to GPLv2, we engaged with the engineering division of Digium (the Asterisk® company), during the development process and have since received an “all clear” with regards to our new architecture. In a continuing spirit of openness, we’d like to share details of our architecture with you.

Our product architecture has three main components, shown in the diagram below.



The key component in our new structure is the Howler Frame Server (HFS). This is a platform component within Howler products that run on the Linux System 5 (SYSV). It’s a completely independent application, whose job is to receive data from the shared memory interface in Linux (SHM) and distribute that to the relevant Howler modules where all the work is done. This portfolio of modules is the second component in the architecture, and includes our “Howlet” software codec and our “Screamer” PCI processing card for higher performance. HFS insulates the user’s application (such as Asterisk®) from the modules, allowing simple upgrades without any change to the application.

The third key component is the Howler Integration Module, which interfaces the HFS to the user’s application, enabling interaction with Asterisk®, Freeswitch, Call Weaver or other VoIP softswitch applications, allowing users’ investment in Howler products to be protected as their requirements evolve. Naturally, the Howler Integration Module is made available as Open Source code under the GNU General Public License.

In addition, all commercial deployments of G.729 Codecs should be “properly licensed from the intellectual property right and patent holders”. We completely agree. Howler's products are fully licensed from the patent holders.. Please visit Sipro’s own web site, where you will see us listed. For every G.729 license we sell, we remit a royalty payment to Sipro.

We hope this makes our position clear. We have gone to great lengths to provide a high-performance set of products that provides huge benefit to the community and yet does not violate the traditional licensing model. Through the use of our reengineered architecture, and with properly licensed rights from the patent holders, we are justified in making the claim that Howler makes possible the use of G.729 with Open Source VoIP Platforms.