Best Free Open Source PBX Software Solutions

PBX (Private Branch Exchanges) are small switches used for setting up connections between telephones within a private organization.

In the absence of a PBX, a company will have to lease a phone line to each employee.
Telephone companies lease only those lines necessary to enable the maximum number of employees to make outside calls simultaneously.

The number of extensions is nearly 10%. All telephones are wired to a PBX. Employees use the outside access code to connect to an outside line when they take the receiver off-hook and dial it.

Enterprise-grade PBX software includes directory-based voicemail, conference calling and integrated messaging, interactive voice response (IVR), three-way calling, caller queues.

These packages are offered without charge and are supported by users who help with the products.

What is PBX (Private Branch Exchange)?

PBX systems make it easy for enterprises to create internal phone connections for enterprise users. A specific number can also be shared for external phone lines.

Business telephone systems are designed to save enterprise communications costs. Utilizing a group phone line enables you to share one line among several employees instead of using separate lines for each.

PBXs use IP connections (Internet Protocol) to communicate. IP PBXs are also PBXs. You can make your communications more effective by using IP PBX.

IP PBXs allow you to communicate via video, voice, and instant messaging.

Top Free and Open Source PBX Software Solutions

In this article, you will find a ranking of the best open-source PBX systems.

Our criteria are based on popularity, updates, latest development, maturity, application relevance, but we welcome feedback based on your own experience.

While the list is quite lengthy, I have tested each one individually and sorted it by the best.

1. Asterisk

In addition to being able to make traditional phone calls, Asterisk performs many other functions. A PBX system that is essentially open-source.

The Asterisk software, along with a PC running Windows, makes it possible to replace existing switches, augment a PBX, add VoiceOverIP, voicemail, conferencing, and a number of other capabilities.

Most IP telephone handsets and software are supported by the PBX system. With Asterix, traditional telecommunications technology and operations are not only reduced, but voice over IP is also becoming more mainstream.

Asterisk enables IP technology to be integrated with existing analog networks to reduce costs.

Asterisk is currently in use in more than 170 countries, with more than one million communications systems. Nearly every Fortune 1000 company uses Asterisk.

As a stand-alone telephone system, or for enhancing or extending an existing system, or for bridging gaps between systems, Asterisk is most commonly used by system integrators and developers.

What Do I Need to Know To Use Asterisk?

Asterisk was originally designed by programmers for programmers. Scripting, networking, scripting, and telephony knowledge are essential for creating applications and solutions with Asterisk.

2. SipX

SipX- PBX sofyware

SipX is an open source PBX for voice over IP. SipX is a software application implementing the Session Initiation Protocol (SIP) that is used to establish IP-based communication systems (IP PBX).

Asterisk’s design differs from that of sipX. In addition to voice mail, IVR, and auto attendant, SimpX has other features.

VoIPX has many of the same features as a private branch exchange (PBX), such as voice mail, interactive voice response, auto-attendant, and the capability to manage and configure the PBX, phones and gateways.

Using Java, Web Services, and Ajax technologies, the software comes with a powerful Web-based configuration and management application.

There’s an open-source alternative to Asterisk now, so it’s not the only game in town. The “sipX” project consists of a SIP-only PBX released under the LGPL. One notable feature is a pre-installed, responsive theme

3. Elastix

Elastix PBX software

There are a number of features for collaboration, email, faxing, and IP PBX that is part of this open-source unified communications server.

There are capabilities such as predictive dialling through the Web interface. A number of software packages are integrated into Elasticix, each offering unique functionality.

Reporting and controlling are improved with Elastix. The Elastix Communications software offers Call Recording, Voicemail, Voicemail to Email, configurable IVRs, voice synthesis support, batch conversion of extensions to CSV files, and Echo Cancellation.

An online phone provisioning tool. Supported IP phones can be configured quickly using this program.

Web-based call centre software and predictive dialling functionalities are part of its features. PBX, fax, instant messaging, and email services are available through the Elastix functionality built on top of open-source projects.

4. FreeSwitch

FreeSwitch- open source PBX software

Open-source cross-platform telephony platform FreeSwitch is designed to facilitate routing and interconnection of audio, video, text and other communication applications.

There is a wide range of free tools available that can be used to develop telephony applications on the FreeSWITCH platform.

Modularity, cross-platform compatibility, scalability and stability were initially designed and implemented while focusing on several design goals. SIP features offered by FreeSWITCH include presence/BLF/SLA, along with TCP TLS and SRTP.

As well as acting as an SBC (session border controller) and proxying T.38 and other protocols, it can also be used as a transparent proxy.



Although OpenSIPs is focused more on the open-source implementation of a SIP server, it can still help you create a unified communication system and a telephone system.

With a modular and scalable model, the platform supports voice, video, instant messaging and presence products, and as with some other platforms, it must be completely customizable.

With OpenSIPs, you have a strong enterprise or carrier level option at an astonishingly fast SIP server.

Benchmarks and performance testing are a continual feature of OpenSIPs to empower their claims. OpenSIPs offers downloadable webinar recordings, in-depth setup and use manuals as well as a webinar archive, similar to Asterisk.

Setup portals on the web should make gathering statistics and information of your service as easy as possible, as well as allowing on-the-fly configurations.

6. CallButler

CllButler- FRee PBX Software

The system is designed for Windows-based computers, and it includes a PBX, an IVR, and an auto-attendant. The product was previously commercially available but is now being released as open-source.

There are several features offered by CallButler, including Text to Speech, Find Me/Follow Me, Call Forwarding/Transfer, Recording, Conferencing, Call Personalization, and Integration with CRM/SFA/ERP/Databases.

Setting it up

I downloaded CallButler Professional for simplicity’s sake and entered some basic information including name, email, and phone number.

It began with a demonstration of its voicemail system, which is then followed by easy three options: ‘you can configure the CallButler for my business,’ ‘View features,’ or ‘Get started now.’

Choose an option from the menu in order to select the type of business, such as General, Storefront, Restaurant, Real Estate, and so forth.

After selecting Real Estate, the system asked me to record a welcome greeting, a menu greeting, information about featured listings, and a voicemail greeting-all of which included sample scripts.

In the next screen, the system will ask for your phone number (landline, mobile, VoIP, etc.) where calls should be forwarded, and you will return to the demo, but this time your recorded greeting will replace the default one.

The setup is straightforward and easy to follow, and the explanation of what you’ve installed is slick, too. It only takes a few minutes to create a simple and customizable auto attendant system.

You then have access to the main menu of the software after completing the initial setup. You’ll find seven tabs right at the top of the website: Extensions, Call Flow, Receptionist, Test Drive, Call Personalization, PBX, and Phone Numbers. Overall, the interface is incredibly intuitive.



Kamailio, a pioneer in open source SIP, creates and grows its open-source software SIP server over the course of fifteen years.

The effort is evident by having synchronous TCP, SCTP, and UDP, TLS to ensure protected communications for VoIP information such as audio, video, and text, as well as WebRTC support.

As well as instant messaging and presence, Kamailio includes advanced features like least-price routing, load balancing, failover for routing and authorization and authentication to ensure increased security.

Considering the level of encryption offered by Kamailio, this is quite possibly the most secure option on this list and could be an ideal selection for any team or maybe a small business that has to keep everything as safe and secure as possible.

Alternatively, Kamailio may be a bit more difficult, requiring a lot more knowledge of the SIP protocol in order to effectively control the platform.

8. CoreDial VoiceAxis 3.0

SIP trunking and VoIP services are offered by CoreDial with its VoiceAxis 3.0 platform for Service Providers and Interconnects.

Enterprise-level businesses and service providers will find this turnkey package to be useful. It is designed to manage, bill, and provision hosted PBX services. Because of its ease of use, it makes a great management tool for the Asterik platform.

Asterisk PBX management software such as VoiceAxis can be used to provide enterprises with an affordable and feature-rich Asterisk PBX implementation.

9. Digium Switchvox

Switchvox open source pbx software

SMB 4.5 Digium, who created Asterisk, offers service packages for businesses that include telephony and other services as well as free software as a platform for developers.
Switchvox is the company’s most successful product.

Most of its products are IP PBXs geared towards small and medium-sized businesses. With the Switchvox SMB 4.5, it is now possible to access features like call recording and visual voice mail directly from compatible handsets as opposed to requiring a web interface.

They were previously added to Switchvox.

Even so, Digium Switchvox offers enough functionality to meet the needs of most operations at a rather competitive price point. Four different phones, all with color displays, come with the device’s hardware features.

Additionally, Digium Swichvox applications for Android and Apple iOS are visually appealing and intuitive. In addition to providing useful tools to monitor calls, queue in real-time, and create reports, Digium offers an administrator console.

10. FreePBX

freePBX Software

With FreePBX, freedom is the keyword. Due to FreePBX’s modular design, it gives users the ability to build phone systems tailored to meet their needs.

This free PBX allows you to build a scalable business phone system for any budget. With a global community of developers, FreePBX remains an extremely flexible platform that allows you to customize all of the features that you need to create your own phone system.

Its community-based development and millions of installations outperform the telecom industry’s commercial efforts.

Despite its name, FreePBX’s software features are free for downloading, configuring, and using –but you will need to incur a few costs before you can get started. As you will need your own SIP trunk provider to be able to place calls with FreePBX, you are still required to pay for an inbound and outbound calling provider in order to use its core features.

Furthermore, FreePBX offers packages that include the Standard Bundle, Advanced

Bundle, Call Center Bundle, and Everything Bundle, which can all be customized individually in FreePBX, but are provided pre-installed and ready to use.


In your quest for 10 Best Open Source PBX Software Solutions, these reviews may have been helpful.

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