Voice over IP (VoIP) enables voice communications over IP networks, including the internet. Instead of relying entirely on conventional telephone infrastructure, VoIP applications transmit audio as digital data. They can be used for everything from personal conversations to large business telephone systems.
SIP is one of the most widely used signalling protocols for internet telephony. It allows compatible softphones, telephone systems and service providers to establish and manage calls. Other technologies, including WebRTC, support real-time voice and video communication through browsers and dedicated applications.
Softphones allow users to make and receive calls using their computers, typically with a microphone, speakers or headset. Some support conventional telephone numbers through a SIP provider, while others use their own communication networks. Calls between compatible internet endpoints may be free, but calling ordinary telephone numbers generally requires a provider and may incur charges.
For businesses, an IP-based Private Branch Exchange (PBX) provides facilities such as extension management, call routing, voicemail, interactive voice response, conferencing and call queues. Linux also offers powerful SIP proxies, media servers and other infrastructure for building communications platforms.
Here’s our verdict captured in a legendary LinuxLinks-style ratings chart. Only free and open source software is eligible for inclusion here.
Let’s explore the 19 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.
| VoIP Software | |
|---|---|
| Jitsi | Innovative open source voice and video conferencing |
| Mumble | Voice chat application for groups |
| Jami | SIP-compatible softphone and SIP-based instant messenger |
| GNU Gatekeeper | Feature-rich project that implements an H.323 gatekeeper. |
| Fluxer | Instant messaging and VoIP platform |
| Kamailio | Build large platforms for VoIP and realtime communications |
| FreeSWITCH | Telephony platform for voice and chat driven products |
| Asterisk | Complete PBX system |
| Wire | Encrypted instant messaging client |
| Galene | Easy to deploy videoconference server |
| Linphone | Voice over IP softphone, SIP client and service |
| Janus | General purpose WebRTC server |
| Baresip | Modular SIP user-agent |
| OpenSIPS | Mature SIP server |
| GOnnect | Easy to use VoIP client |
| Calls | Make phone and SIP calls |
| Ekiga | VoIP and video conferencing application for GNOME |
| qTox | Chat, voice, video, and file transfer IM client |
| Empathy | Instant messaging and voice over IP client |
his article has been updated to reflect the changes outlined in our recent announcement.
 Explore our carefully curated directory of recommended free and open source software, covering every major software category.The directory forms part of our extensive collection of articles for Linux enthusiasts. It includes hundreds of detailed reviews, together with free and open source alternatives to proprietary software from companies such as Google, Microsoft, Apple, Adobe, IBM, Cisco, Oracle, and Autodesk. LinuxLinks also covers interesting projects worth exploring, Linux-compatible hardware, free programming books and tutorials, and much more. Know a useful free and open source Linux application that we haven’t covered? Tell us about it using our submission form. |
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Article has been revamped, removing proprietary software. Ratings chart added.
… and you forgot for the most secure one? Signal.
https://www.signal.org/
Signal is a great instant messaging chat, and while it has voice and video calling functionality, that’s not where its strengths lie. For a great VoIP client, try Blink.
Actually, Signal is the gold winner of the Instant Messaging Software https://www.linuxlinks.com/linux-means-business-instant-messaging-best-free-software/.
The key is that Signal is excellent at instant messaging, but it’s not a great soft phone. I don’t actually think the author forgot Signal as you contend.
The Signal website states
“To use the Signal desktop app, Signal must first be installed on your phone.”
So not much use unless you have a portable personal electronic tracking device otherwise known as a cellphone.
Also Signal is written mainly in Typescript. TypeScript is a free and open-source high-level programming language developed by Microsoft.
Yet another Microsoft language trojan. No thank you,.
We know that there are lots of software enthusiasts who dislike Microsoft software. That’s one reason why we created
https://www.linuxlinks.com/best-free-open-source-alternatives-microsoft-products-services/
Maybe we should add an article about alternatives to TypeScript. We’ll think on that.
Is it just me but I really loathe Electron based software.
Mate, there are some really great Electron apps out there. A few of my favorites are Atom, Discord, and Light Table.
True. Some of the Electron software is just pathetic. For example, Ubuntu client for OnSIP. Not only it is huge (almost 600 MB), but also works with significant lag! It is a good example of the Wirth’s law: ” software is getting slower more rapidly than hardware becomes faster”.
I do think ring deserves a look
Ring isn’t bad but it’s better at instant messaging than as a soft phone.
Ring did feature in our Instant Messaging Clients article https://www.linuxlinks.com/instantmessaging/.
I had been using Yate, which could place outgoing phone-calls through the server at gmail.com.
It quite working, though, Can any of these clients connect through the gmail or skype servers to the telephone network?
I’m pretty sure Skype can connect to Skype servers.
I use Google Voice from inside GMail on my Ubuntu 18 laptop and it still works just fine as long as I am logged in from Chromium. Free to US and Canada
I have a Samsung Note 4 I would like to put a Linux smartphone distro on. I would like to use it for phone calls over internet. Recs RE best OS for this and best “phone” app to dial phone calls to regular phones? Many thanks in advance.