Adopting an existing VOIP service from the top PBX providers is a suitable solution for many companies. But it is not an easy job to find the right one.

Providers are constantly trying to individually fit the needs of every customer. Finding the right solution for every use case might be almost impossible, keeping in mind the team size, required features, and security issues. 

Companies can try out open-source solutions or platforms for all those cases when a service does not fit their expectations and requirements. 

Are there really free PBX solutions? Yes, there are. These are open-source PBX software solutions. Necessary hardware needs to be provided, which is a suitable computer.

Any business can develop and tailor its own in-house PBX applications using free PBX software. The source code is available online and can be tailored for every specific scenario.

ASTERISK

Asterisk is “the father” of all open source PBX and VOIP solutions. It is the leading open-source telephony platform, with enormous feature lists which only continue to grow. 

The Asterisk toolkit is used by a mass quantity of developers around the world. Many of the suppliers on this PBX list have either begun with or are based completely on the Asterisk project.

It is packed with the standard PBX VOIP features. They consist of an automatic telephone, an interactive voice response menu, conference calling, and voicemail. 

The Asterisk makes it easy to turn any computer into a PBX. 

As a popular platform Asterisk provides web classes and tutorials to help users do their job with the platform.

VITALPBX (GUI)

Compared to the other free solutions on this list, VitalPBX is rather new. And while the first version was released in early 2018 they have worked really hard and are now offering a well-developed feature-rich product.

The VitalPBX platform can be installed on physical hardware or the cloud. It is essentially a Linux-based Graphical User Interface for Asterisk and as such, it can be run with minimal effort. The interface is well structured and its features are easy to find and use.

VitalPBX is completely free to use, a professional support package and add-ons are available as paid options.

SIP FOUNDRY

SIP Foundry provides many of the solutions that the Asterisk engine can power. You can construct your own voice and video communications with SIPFoundry. Also, it supports conference calls, messaging, and chat. Like with Asterisk, the platform includes everything you might need to build your own PBX solution.

While Asterisk is 100% free and open-source, SIPFoundry has a somewhat different spin. It offers professional paid assistance to developers based upon customer needs. It might seem like excess income, adopting a support team might be an essential step for some businesses looking to build their own system. With a focus on the marketplace, the tool is free for commercial or private use. 

This project has some of the features taken from the HylaFAX, FreePBX, Openfire, and Postfix open-source projects.

ELASTIX

Elastix brings in Asterisk’s features and other such projects, all under one easy-to-use interface. 

Elastix supports a wide range of hardware consisting of Yeastar, Dinstar, Digium, Yealink, and Snom. It was one of the first distributions that included a call center module. 

And it continues to supply the solution-free under the GNU General Public License.

Currently, Elastix is owned by 3CX  and can be found in 2 versions (OLD and NEW). The old one is still preferred by many but lacks in security as it is discontinued and gets no security updates. The new version is just the Linux version of 3CX now.

ISSABEL

Issabel is the unofficial successor of the old Elastix. It offers way better security and frequent patches.  The platform is a lot better looking and feeling and they have spent a good amount of time cleaning it. 

The platform is free. It is open-source and there are not many pricing options or catches. The support is paid and there are a few paid add-ons. The source code can be freely downloaded from SourceForge or GitHub

Issabel uses addons that help satisfy almost every need. Lately, they have also worked hard on their API so you can expect a lot more than the old Elastix.

That being said we must mention that there is almost no documentation on Issabel and half of the available information is in forums making it hard to find.  The other half of the information is sadly in Spanish.

FreeSWITCH

Free SWITCH was also based on the Asterisk platform and was created and developed by three of the original programmers of the Asterisk platform. Anthony Minessale II, Brian West, and Michael Jerris.

FreeSWITCH is with a focus on the modulators, cross-platform service, availability, and stability. 

It provides one of the most flexible platforms to construct your own UC package. FreeSWITCH supports SIP, H.323 as well as WebRTC to leverage the latest advancements in technology. 

It can integrate and interface with some of the other open-source PBX platforms. For less complexity, FreeSWITCH utilizes open software libraries that perform essential functions. FreeSWITCH delivers the calling features and some extras such as speech recognition. It also offers PSTN ports for digital and analog circuits.

VOICETRONIX

Voicetronix is an equipment supplier, an open-source platform, and also an assortment of hardware. 

This is a web-enabled PBX program. It comes with a web-based user management portal, in addition to a management GUI for easy and rapid configuration. It features car attendant, automatic call distribution, call routing search groups, and even voicemail. Unique features like call hunt groups, music-on-hold, and call records are a good solution for businesses in need of basic call center software. 

With CRM-baked and enabled into the platform, users may not require to adopt a separate CRM solution, saving time and money.

PBXINAFLASH

PBXInAFlash’s main feature is the ability to set up your own PBX server in no time. The project has everything needed to set up a PBX system in less than an hour. 

It uses CentOS, with an integrated Apache web server, SendMail server, and MySQL database, in addition to firewalls and all essential protocols. 

Users have the option to pick from dozens of add-ons to tailor the system. Backups, Caller ID lookup services, SSL keys, Google Voice integration, and fax support to name a few. PBXInAFlash seems to be the easiest and the quickest solution to adopt.

FreePBX (GUI)

FreePBX combines the best of both worlds and leverages the work. The project uses the Asterisk system. This is the most recommended free PBX for new users.

Users may download either just the GUI or the whole package. It consists of a pre-configured OS, Asterisk, and the FreePBX GUI. So while by adopting Asterisk, some knowledge may be required to take advantage of, or to create your own GUI, FreePBX brings it all together. FreePBX makes it feasible to establish your SIP Trunks that are part of the platform thanks to the integration. FreePBX also contains a long list of commercial modules and add-ons to enhance your system with even more features.

opensips

With OpenSIPs it is easy to set up your own PBX. It focuses on the open-source implementation of a SIP server.  The platform supports video, voice, IM, and presence services. It is using a modular design, it is scalable and very much customizable. 

OpenSIPs offers enterprise-class SIP server solutions and a very fast one at that. OpenSIPs has made a list of benchmarks and performance tests to back their claim up. 

OpenSIPs often records webinars and makes in-depth manuals for configuration similar to Asterisk.

A web interface makes it easy to collect data and shows on-the-fly configurations.

BITRIX24

Bitrix24 offers its free virtual and PBX solutions to small businesses. And it comes with quite a lot of free, and handy business tools. Their PBX is also based on VoxImplant which is actually a good sign. Keep in mind that there might be some small fees and taxes involved when adding phone numbers.

Bitrix24 is not focusing mainly on the VoIP or PBX market and is trying to sell you its customer relationship management (CRM) software along the way. If it were not for that, we would have highly recommended them.

KAMAILIO

Kamailio is an open-source project with 15 years of constructive development. The original company left the project, but it continues to expand. Both the SIP server and Kamailio project continue to be built on.

It features UDP asynchronous TCP and SCTP, TLS to ensure secure communication. VoIP data consisting of voice video and text, and even WebRTC support is also present. Kamailio also supports instant messaging, least-cost routing, load balancing, routing failover. 

With authentication and authorization for enhanced security, as well as a high level of encryption Kamailio offers the strongest level of security on this list. It makes it a good recommendation for any staff or business that needs to keep everything as locked down and protected as possible. As a result of all that, Kamailio may be a bit more challenging to adopt.

3CX

The 3CX Phone System is the last open-source PBX based on the SIP standard. This solution allows extensions to make calls on the PSTN or standard services. 

The platform also offers an easy-to-understand web-based GUI. The setup process is actually simple – an executable file. 

3CX supports iOS and Android for mobile customers. Windows and Mac softphones are supported, too. It appears to take out the hassle of development required to establish your own PBX server. WebRTC adoption makes web conferencing possible. Click2Call and CRM are also part of the features. 

Like the rest, an internet training academy is available for users to understand how to manage the platform.

Phương Nguyễn