13 Best Free Linux Voice Over IP (VoIP) Software – Updated 2018

Voice over IP (VoIP) software enables telephone-like voice conversations across IP based networks. A VoIP phone service is often cheaper than a traditional Public Switched Telephone Network (PSTN) phone service and removes geographic restrictions to telephone numbers.

SIP is the most popular VoIP protocol. This protocol enables two or more people to make phone calls to each other using the Internet to carry the call. SIP to SIP calls on a broadband internet connection are high quality, always free regardless of distance, and offer additional functionality such as free voicemail to email and phone numbers, caller ID, 3-way conference, speed dialing, call forwarding, simultaneous ring, call waiting, call return, caller ID block, and anonymous call rejection.

Softphones are user based clients for making and receiving voice and video communication over the IP network, usually permitting integration with USB and IP Phones instead of a computer’s microphone and speakers (or headset). This article selects the best softphones available for Linux.

For enterprise or business markets, VoIP enables the enterprise to manage a single network (the IP network) instead of separate voice and data networks, while enabling advanced and flexible capabilities to the end user. With the credit crunch still to take full effect, it’s even more important for small businesses to minimize their costs. One way to reduce expenditure is to switch from a normal telephone contract to using VoIP. Calls made using VoIP work and sound like normal telephone calls, but cost significantly less. Public Branch Exchange (PBX) is a private telephone exchange which routes calls internally and provides call queuing, hunt groups, conference calling, voicemail and more. The PBX enables many phones to use a single VoIP connection.

We have included Skype, Discord, and TeamSpeak on our recommendations. While these applications are all available for no-charge, they are not released under a freely distributable license. They are therefore not ‘free’ software. However, given their importance and the quality of the applications, they certainly warrant our recommendation.

This article includes a single Tox client recommendation. Tox is a peer-to-peer instant-messaging and video-calling protocol that offers end-to-end encryption. I’ll cover other good Tox clients in more detail in a forthcoming group test.

So, let’s explore the 13 VoIP software at hand. For each application we have compiled its own portal page, a full description with an in-depth analysis of its features, screenshots (where relevant), together with links to relevant resources. Start making free calls today.

Read our complete collection of recommended free and open source software. Our curated compilation covers all categories of software. The software collection forms part of our series of informative articles for Linux enthusiasts. There are hundreds of in-depth reviews, open source alternatives to proprietary software from large corporations like Google, Microsoft, Apple, Adobe, IBM, Cisco, Oracle, and Autodesk. There are also fun things to try, hardware, free programming books and tutorials, and much more.