Best 08 Free Sip Server Software

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A SIP server or Session Initiation Protocol server is a must require tool if you want to start a business regarding Voice over IP telephony. SIP is open-source server software that comes to hooks up computer programs or libraries. And it’s the key element of an IP PBX and primarily deals with handling all SIP calls in the network. Hence, you’ll learn very different servers’ names with their pros and best features that will deliver from this post.

Before knowing the best free sip server software, let’s have a quick chat about sip server. The complete form of SIP is the Session Initiation Protocol. And it’s a TCP/IP-based web protocol that uses for connecting and controlling customer contact. SIP comes with VoIP (Voice over IP) telephony to set up links for phone calls, and its main features are defined in SIP RFC3261.

But a Session Initiation Protocol server is also familiar as a SIP proxy. It is responsible for soliciting requests from user agents to make and stop calls. And this server empowers you to control call cohesions in VoIP solutions. So, you can tell, this server can:

  1. To set up a relation between countless endpoints.
  2. Using the SDP protocol to start the media parameters for the endpoint
  3. Change and revise the parameters during the session.
  4. Restore one specific endpoint with another or a unique endpoint
  5. Session consummation

Now that you’ve learned what it is and how its server works, it’s time to get the best free open source sip server. And sad but true, if you search online about this topic, you’ll find many resources. But all are not as good as applicable. Hence, to make your job easier, I’ve developed a handy list that can provide your desired software.

Free SIP Server Software:

So, without further delay, let’s jump deep to find out the best gems for you to use.

SIP Server Asterisk:


Asterisk is the materialization framework for PBX (Private Branch Exchange). Also, it’s the number #1 and free open source sip server software for making your private communication apps that Sangoma sponsors.

Mark Spencer of Digium built and designed it in 1999 initially for Linux. But it works perfectly on several operating systems such as macOSNetBSDSolarisFreeBSD, and OpenBSD.

Highlighted Features:

  1. Call Monitoring, Transfer, and Waiting
  2. Append Message, Blind Transfer, and Blacklists
  3. Making Real-time Communication Solutions
  4. Automatic Call Distributor Functionality
  5. Multi-protocol Solutions

On a quick note, it has 2,000,000 Downloads Yearly86,000 Community Mates, and 170 Countries with Installations. Also, it includes 1,000,000 Servers Globally and 1,300,000 Fresh Endpoints per year.

Open Source FreePBX Software:


FreePBX is the most famous free open source IP PBX tool worldwide. It gives you the freedom to create a phone system to suit your needs. And to create a scalable company phone system on any cost limits, it covers all the vital features.

Apart from that, it’s entirely free to download and exemplary easy to use. The global developer’s community ensures high compatibility and a customizable platform. Also, it’s a web-based graphical user interface (GUI) to manage Asterisk ( a Voice over IP) and telephony server.

Top Features:

  1. SmartOffice Access, Phones, and Appliances
  2. Session Initiation Protocol Trunking, VoIP Gateways, and Modules and Add-Ons
  3. Session Border Controllers
  4. Participate and Report Issues on Community Forums
  5. Bug Submissions

Above all, it has millions of installations globally with a very active blossoming base.

Most Popular Elastix Tool:


Does your communication need a PBX, Live chat, or Video? Want Video Conferencing, Presentation, and Teamwork tools in real-time? Okay, no problem, in this case, you can use Elastix. No need for any add-on fees or additional downloads, and you can easily install it on Windows, Linux, or Raspberry Pi as an on-premise solution.

Besides, it’ll help you with working remotely, sharing screens, no time limit for endless users, and so on. Also, it gives you the ability to flip web visits into leads and sales, leading call center features and narration, and much more.

Promising Features:

  1. App-free Online Conferencing
  2. Easy Install and Management
  3. Live Chat and Call with Site Callers
  4. Answer Fb Page Notes
  5. Offers Top class Client Service

And most importantly, it’s 24/7 available from your remote desktop or mobile gadget.

Award Winner Tool Vicidial:


Now, it’s time to introduce the most famous contact center solution worldwide named Vicidial. It’s an award-winner tool that grabs many awards regarding contact centers. And it found in 2007 through its real maker and initial developer, Matt Florell.

However, it can help you with single-agent call queuing, lead import web-based API, place emerging CallerID per operation or per list, and more. Also, it has a distinct Time-clock app to track user working time.

Best Features:

  1. Inbound email operating via agent web screen
  2. Call up to two different client numbers manually or automatically for the same lead.
  3. Run a campaign to auto-dial and forward live calls to public agents.
  4. Capability to auto record all calls
  5. Real-time campaign display screens and 3rd party blind call transfer

On top of that, it has more than 14,000 installations in 100 countries in 16 distinct languages.

Best Buddy Kamailio:


If you want to manage more than thousands of calls settings per sec, in this case, Kamailio will be your best buddy. It’s published under GPLv2+ and used to build vast platforms for Voice over IP (VoIP) and real-time communications. For example, you can be used this tool for instant chatting, WebRTC, and many various apps.

Also, it may best fit on climbing up SIP-to-PSTN gateways, media servers, or PBX systems. On the other hand, you can use it with limited resources and carrier-grade servers. And to provide high performance, it’s written on Unix/Linux systems, including architecture-specific optimizations.

Powerful Features:

  1. Asynchronous SCTP, UDP, and TCP
  2. Secure services through TLS for (voice, video, text) VoIP
  3. WebRTC (IPv4 and IPv6) on WebSocket support
  4. Routing fail-over, Least cost routing, and Load balancing
  5. Many backend systems support

In a word, its main aim is to be a combined habitat for its users to thrive on protected and scalable Session Initiation Protocol servers.

Telephony Network Solution GNU SIP Witch:


The GNU SIP Witch designs to come forward to support telephony services network scaling instead of the excessively compute-bound solutions we use. It uses the Session Initiation Protocol to provide a protected peer-to-peer VoIP server. It comes as free software under the GNU General Public License (GPL) version 3 or later.

In addition to that, it’s constructed amazingly for macOS, BSD, Windows, and Linux, also for Android support. And it’s written in C++ and uses the uCommon programming language. So, it’s all about liberty to communicate and remove artificial fences and restrictions.

Robust Features:

  1. Presence information and text (messages)
  2. Supports encrypted calls and Enables NAT traversal
  3. Installed Ubuntu and Fedora directly
  4. Call Forwarding, Distribution, and Hold
  5. Self-organizing Peer-to-peer Telephone Network

On a serious note, it was used as an element of the GNU Free Call, making it a substitute for Skype.

Hey folks, now we’ve comes at the very end times of the listing. Did you find the answer to what you were looking for? If not, make a note to us, let’s consult, and we’ll make you flourish.

Or, want to know what about the future of VoIP technology for starting a business? In this scenario, you can read our other blog post, “How To Start A VoIP Business in 2022.”

Now come back to our topic…..!

Session Initiation Protocol proxy OpenSIPS:


OpenSIPS is a Session Initiation Protocol proxy or server for Voice, Video, IM, Presence. And it brings a potent and performant (Session Initiation Protocol RFC3261) Registrar, Location, or Redirect server. It also includes a springy and mighty scripting code for routing logic. It’s also the fastest server tool to deliver scalable explanations at an enterprise level.

On the other hand, it presents high-level technical solutions in professional platforms. For example, it gives technical solutions like Quality, Performance, and Security.

Key Features:

  1. Digest and IP Authentication
  2. Modular Architecture
  3. PERL Programming Interface
  4. UDP/TCP/TLS/SCTP Transport Layers Support
  5. SRV and NAPTR DNS Support

To clarify, it has a command interface through FIFO files and UNIX sockets.

Effective Server Tool Flexisip:


Are you thinking of an effective and scalable Session Initiation Protocol proxy for topical routing of intercom calls? Okay, here is a server tool named Flexisip that will make your thought vanish. It’s ideal for integration within low-footprint embedded designs and massive cloud deployments.


  1. Real-time presence status and statistics
  2. Push notifications and Group chats
  3. Recognizing users of service
  4. Easy network deployment to Multicast DNS

Moreover, it’s easy to install, and you can use it for various purposes.


Before picking a free sip server software from the above listing, please remember that a solo server can’t meet your every desire. Because every single sever has its distinct pros and cons. So, you’ve to choose wisely the best open source sip server that fills most of the requirements.

At last, I hope this post has enough info to grab the best server and make a path to start your business instantly. And if you like this blog post, please share it as much as possible with your friends and family, including social media.

Rest assured, this blog will never lead you astray but will support you from your side. And I hope you’ll be with us for our more engaging, attractive, and informative posts.

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