FreeSWITCH Development

Lintel specializes in custom FreeSWITCH programming and configuration, integrating soft-switch functionality into a variety of business applications. With nearly 10 years of experience building custom telephony, we've got the know-how to help you find the right strategy for introducing voice/telephony into your products and services.

The Value of Experience

Samples of our work include several highly-customized call centers, complete with dialers, IVRs, voicemail, calling queues, and rich desktop clients. We've also created an LDAP-based PBX solution with automated endpoint provisioning, a SIP-based load tester capable of running thousands of concurrent sessions for stress-testing Asterisk, and other SIP-based VoIP servers.

Fast and Affordable

Lintel sponsors the development of ParselTONE, an open source framework for building custom voice-enabled products based on FreeSWITCH, Python, and a variety of other open source technologies. By leveraging the ParselTONE Telephony Framework wherever we can, Lintel is able to develop voice applications more rapidly and affordably than otherwise possible.

ParselTONE, like FreeSWITCH itself, is released under the business-friendly Mozilla Public License (MPL), so we can develop your solution on top of ParselTONE without any ownership or licensing concerns.

Lintel has also made several contributions to the FreeSWITCH project in the form of paid bounties for new features that enhance the code base, which benefits everyone who uses FreeSWITCH. Our experiences with the bounty process have been so positive that we’ll almost certainly be sponsoring future bounties.


Many telephony solutions are more popular than FreeSWITCH, but none are more powerful, flexible, or configurable. A few of the reasons we prefer FreeSWITCH over the alternatives include: its ability to be dynamically configured and controlled via HTTP; its business-friendly license; and its smart reuse of other popular open source libraries such as Nokia’s Sofia SIP stack, and the Apache Portable Runtime project. We also like FreeSWITCH’s powerful event engine; and the fact that it runs on all major operating systems doesn't hurt. Seriously, though, FreeSWITCH is awesome.

Perhaps the most compelling reason we choose FreeSWITCH is its architecture; it was built from the ground up as a soft-switch (not a PBX), and design decisions were made with the benefit of lessons learned from other open source telephony projects.

For most productized telephony integrations, FreeSWITCH is the obvious choice. Lintel’s custom-built FreeSWITCH applications have made hundreds of millions of calls; and our clients love the performance, scalability, and flexibility FreeSWITCH brings to their products.

About FreeSWITCH

FreeSWITCH’s modular architecture provides a development platform for a broad range of telephony applications, from softphones and PBXs to soft-switches. FreeSWITCH supports Skype, SIP, GoogleTalk, TDM, and other popular communication technologies. Common implementations include rating and routing servers, conference bridges, voicemail servers, IVR and announcement servers, SBCs, and fax servers.