Compare the Top 10 Best Open Source PBX Software of 2025

One of the reasons why hosted PBX services are so popular is that they can meet the needs of a variety of businesses, ranging from home-based startups, all the way to large enterprises with operations on several continents. While hosted PBX providers offer packages that work for most businesses, they may not be the best solution for everyone. Some businesses require specific features or better security than cloud hosted PBX products can offer.

For businesses that need a more customized solution, there are plenty of open source PBX software solutions to select from. These software packages are highly customizable and can be adapted to meet the unique needs of any enterprise. An in-house or third-party development team can tailor the PBX software to make it do exactly what a business needs. If needed, an open source PBX can even be turned into a full unified communications suite.

Here are the best Open Source PBX Software suites:

3CX

3CX is a business phone system that has received many positive comments from companies that use it, with many users praising how simple it is to operate. It offers features that let you work with both standard PSTN and VoIP phone systems. The whole platform is easy to set up and can run on a Windows server. This feature will be quite welcome for those who would rather avoid having to configure a Linux box just to deploy their own PBX.

Using 3CX is very convenient, as iOS, Android, Windows and Mac clients are provided. Of course, you can just use any other SIP-compatible softphone with your system. 3CX takes advantage of the power of WebRTC to bring you video conferencing functions too.

Finally, you get several functions that will simplify the way you connect with your leads and customers. The platform lets you add "Click to Call" functionality to your web pages or mobile apps, in addition to supporting integration with many of the leading CRM systems. There is a full academy of online reference and training materials available to help you understand how every aspect of the system works.

Learn more about 3CX

Asterisk

Asterisk is basically the gold standard when it comes to open source VoIP systems. It's an open source PBX platform that is used around the world by a variety of businesses of all sizes. In fact, many providers of cloud-based PBX solutions use Asterisk to power their service.

The main advantage of using Asterisk is that it has a huge list of features that continues to grow year by year. With this open source system, you can turn any computer into a complete communications server. All of the common PBX features, such as voicemail, IVR, rule-based call routing, automatic call distribution and conference calling are there. The Asterisk PBX platform is completely free and open source, so you can deploy it and modify it as you need without having to pay any licensing fees.

As Asterisk is the most famous open source PBX out there, there is no shortage of informational material about it. There are online courses, manuals and live web classes offered by Digium, the company that supports Asterisk, as well as many third parties.

Elastix

This open source software package offers a complete unified communications solution, which includes an IP PBX, combined with fax, email, IM and collaboration functions. Elastix was originally based on the Asterisk platform and is used by many entrepreneurs who need a convenient and flexible communications solution for their new business. It's completely free to use, no matter the size of your business.

The Elastix solution combines functionality from a variety of open source PBX solutions besides Asterisk, including Openfirm and HylaFAX. You get powerful features brought together under a simple interface. If your business runs outbound calling campaigns that require reaching a large number of prospects or customers, you'll be happy to hear that Elastix includes a call center module that comes complete with a predictive dialer.

SIPfoundry

Since 2004, SIPfoundry has been one of the main competitors to the Asterisk open source PBX platform. In terms of features, it offers much of the same functionality that the Asterisk engine can deliver. You can customize SIPfoundry to create a communications system that is fully tailored to the needs of your business.

Whether you just want a system with basic calling features or to build a full unified communications suite, SIPfoundry has something to offer. It supports voice and video communications, IM and chat functionality, unified messaging and has a mobile client. Since it was first launched, this open source system has been deployed by a wide range of businesses, organizations and government entities around the world.

As SIPfoundry is an open source PBX, you can download it, set it up on your own server (on premise or cloud) and modify its code as needed, all for free. However, the team behind this PBX solution does provide professional support packages at affordable rates to businesses that need them, starting at $495 per month for up to 100 users.

FreeSWITCH

The FreeSWITCH platform was created by three of the original developers who worked on Asterisk. It gives you everything you need to build your own unified communications suite and adapt it to the needs of your business. The platform is modular, so you can add only the components that you need to run your system. This results in better stability and makes the whole system easier to use.

The team behind FreeSWITCH believes in leveraging the latest advances in technology, so you'll find that the platform supports all of the top communications technologies, such as SIP, H.323 and WebRTC. When you build a unified communications system using this platform, integrating it with third-party apps, systems and software is also quite easy when compared to other open source PBX systems out there.

FreeSWITCH provides you with all of the standard calling features you would expect from an enterprise-grade PBX, as well as some rather unique ones. Examples include speech recognition and synthesis modules, which can be very useful if you're building a custom IVR.

PBXInAFlash

PBXInAFlash is a turnkey PBX system focused on ease of setup and use. If you want the simplest solution to deploy your own PBX, you should definitely consider it. With this system, you can get everything set up in less than an hour, even with just minimal technical experience. The system runs on the CentOS Linux operating system and includes all of the components needed to build a customized PBX that will suit the needs of your business perfectly.

The installation package includes everything you'll need to get your system up and running. During setup, you'll get to choose whether you want your PBX to run on an Asterisk or FreePBX version. The installer will also set up MySQL database, SendMail and Apache web servers for you. If you need help at any step of the process, there are plenty of free reference materials available on the PBXInAFlash website.

With this simple PBX solution, you'll get a rich set of features like called ID lookup services, integration with Google Voice and other cloud-based services, faxing support and automatic backups. The system is also one of the most reliable and bug-free that you'll find on today's market.

OpenSIPs

When you deploy open OpenSIPs on your server, you'll get the chance to create a unified communications service that you can truly call your own. The platform is built around a scalable and modular design, which makes customization easy. As anyone would expect from a true unified communications platform, OpenSIPs supports not only voice, but also IM, video and presence services.

What sets OpenSIPs apart from the rest of the crowd is that it has been recognized as one of the fastest open source SIP servers. You can control your PBX with a web-based portal, which allows you to access all of the important statistics, as well as quickly make configuration changes. If you need help getting the platform up and running on your server, you can take advantage of the detailed manuals and tutorials provided on the OpenSIPs website.

Kamailio

The Kamailio platform is maintained by an experienced team of developers with over 15 years of solid industry experience. New features and functions are added to it on a regular basis, so you'll never have to worry about your PBX falling behind on the latest technology.

Kamailio is one of the most secure platforms out there, offering numerous authentication and authorization methods. This makes it an excellent choice for businesses that deal with private information on a regular basis, such as companies operating in the medical or banking fields. Not only is the platform highly secure, but it also comes with some highly advanced functions, including automatic load balancing, routing fail-over and least cost routing. If you want to use it to build a unified communications solution, you'll be happy to see that data and texting are fully supported as well.

The main drawback of this open source PBX system is that it's advanced enterprise and carrier grade functions make it more difficult to adopt compared to others. But if your team has in-depth knowledge of VoIP systems and the SIP protocol, they should be able to get it running flawlessly without too much difficulty.

FreePBX

If you want to take advantage of the power, flexibility and functionality of the Asterisk open source PBX in the simplest way possible, FreePBX is an open source platform you'll definitely want to look at. It gives you a web-based GUI that makes deploying and running an Asterisk-based PBX easier than you would have ever thought possible.

FreePBX provides you with a lot of flexibility. If you already have an Asterisk system up and running, you can download and install just the GUI. But if you want to set up a complete PBX server, you can get the full package, which includes a pre-configured Linux OS, the Asterisk system, the GUI and all dependencies needed to make everything work together.

Users who need to establish their own SIP trunks will be happy to know that FreePBX comes with SIPSTation already built in. If you're looking for ways to customize and expand your PBX further, there are plenty of open source and commercial add-ons you can use that will provide you with practically any feature you could want from a commercial phone system.

OpenPBX by Voicetronix

Even though Voicetronix is a company that is more widely known for their telephony equipment, they also produce a high-quality open source PBX software package. Their system is made up of a web-based application and user management portal, combined with a GUI that you can use on the back end for easy system configuration. All common PBX features, such as voicemail, hunt groups, call distribution, music on hold, call recording and auto attendant are there.

Businesses that regularly interact with a lot of customers will appreciate the fact that the platform comes with a built-in CRM system. This is especially attractive to companies who would rather avoid having to go through the trouble and expense of using a standalone CRM solution.

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