A Complete List of Open Source VoIP Software


Open source VoIP software is a great tool for businesses, not only because it saves thousands of dollars a year in telephony costs, but also because it can be customised according to a specific business’s needs. VoIP software allows businesses to conduct voice conversations across IP-based networks, including voice and video calls, chatting and conferencing.

There are different types of VoIP software, including SIP proxies for building scalable and reliable SIP-based VoIP networks, monitoring software that monitors network traffic, stacks and libraries for developing and refining VoIP systems, and PBX (private branch exchange) and IVR (interactive voice response) platforms for IP telephony.

Here’s a list of open source VoIP software available on the market:

SIP proxies

  • Clearwater: An open source IP Multimedia Subsystem implementation for vastly scalable utilisation in the Cloud. Its SIP routing components are built on PJSIP.
  • Elastix: An open source unified communications server that supports chat, mail, fax and video conferencing.
  • JAIN-SIP Proxy: Can be used in SIP proxy servers, SIP user agents and test tools, as well as to build session border controllers, resource adapters for JAVA, and SIP servlet implementations.
  • Kamailio: Formerly OpenSER, this is a SIP server and registrar with TLS support for VoIP and real-time communications. It also offers SIP authentication, diameter, RADIUS, ENUM and least-cost-routing. Other features include instant messaging, load balancing, fail-over routing, accounting, and support for backend systems.
  • MiniSIPServer: A small Perl POE-based SIP proxy that offers enterprise communication services like ringing- or hunting-group, follow-me and call queue. Can run on multiple operating systems and virtual machine systems. It also works on an IPv6 network.
  • MjServer: Cross-platform SIP proxy, registrar and redirect server. It’s written in JAVA and based on the MjSIP stack, which is used to initiate voice/video/multimedia sessions for interactive and noninteractive applications. Also includes call control, user agent and session border controller implementations.
  • Mumble: An open source, low-latency voice chat software mainly for gaming use. It also offers encrypted communication and key authentication. You can even recognise friends across servers.
  • MySIPSwitch: SIP proxy server that allows the use of multiple SIP accounts with just one SIP login. It also allows central management of any SIP-based VoIP service.
  • NethidPro3.0.6: An open source SIP encryption bridge – an anti-blocking VoIP encryption system that supports using HT serial encryption VoIP gateway.
  • Net-SIP: A Perl SIP framework which comes with a stateless proxy.
  • OpenJSIP: An open source distributed standalone SIP proxy, registrar and location service that is run by JAVA VM. It’s based on NIST SIP (various SIP applications, tools and libraries in JAVA) and comes from the JAIN-SIP proxy.
  • OpenSBC: SIP proxy, registrar and B2BUA that includes NAT traversal, ENUM, and reference implementation of session border controller. It can be expanded and modified based on personal needs.
  • OfficeSIP: An open source SIP server for Windows to make voice and video calls and deliver instant messages between computers for free.
  • OpenSIPS: Derived from OpenSER, it’s a SIP proxy/server for voice, video, presence, IM, and other SIP extensions.
  • party SIP: A flexible and customisable SIP proxy server with different plugins to add or remove capabilities. Users can disable useless functions and allow new ones with little development.
  • Repro: From the reSIProcate project, it’s a free open source SIP server. It comes with a full implementation of federated VoIP and a built-in web user interface for fast setup.
  • Remwave: A high performance cross-platform SIP proxy that’s written in JAVA.
  • SaRP: SIP proxy in Perl, but a cross-platform C++ version is in the works.
  • SIP Express Router (SER): High performance SIP proxy, router and registrar. It also offers SIP authentication, diameter, RADIUS and ENUM. It can easily fix operational issues such as broken network components and is scalable from small office environments to acting as a PBX or Asterisk replacement.
  • Sippy B2BUA: SIP back-to-back user agent server software. It’s a call controller, maintaining complete call state and participating in all call requests. It can perform accurate call accounting, fail-over call routing, prepaid rating and billing, and more.
  • Siproxd: A masquerading SIP proxy server that can run on Linux, Mac OS X, and other Unix derivatives.
  • SIPVicious: A suite of tools for auditing SIP-based VoIP systems.
  • SipXecs: A complete, native SIP PBX solution for Linux. It provides instant messaging, voicemail, user portals, admin GUI, and plug & play management.
  • Vocal VoIP Software: Has a SIP server with network stack. Can be customised to business needs and also provides call routing, call control and billing information for Linux. It’s capable of adaptation and scalability.
  • Yxa: A set of SIP server applications written in the Erlang programming language.

Monitoring software

  • Aheeva Contact Centre Suite: An all-in-one contact centre that offers remote monitoring, contact management and network analytics.
  • Homer: An open source SIP capture system and monitoring application. It comes with HEP, IP Proto 4 (IPIP) encapsulation and port mirroring/monitoring.
  • Kamailio: It offers SNMP (Simple Network Management Protocol) monitoring, which monitors network devices for conditions that require administrative attention.
  • MonAst – The Asterisk Monitor: HTML interface that acts as an operator panel for Asterisk for displaying user/peer status and calls. It uses a reverse AJAX, Python and PHP for originating, transferring and hanging up calls, as well as managing queues and meet me rooms.
  • nProbe: An open source NetFlow Probe for gigabit networks. Offers precise VoIP traffic monitoring to build accurate analysis applications.
  • ntop: Provides VoIP network traffic monitoring with simple metrics.
  • OrecX: Records, monitors and replays calls for contact centres and business VoIP providers. The software can be localised and customised for free.
  • PJSIP-perf:  Monitors and tracks SIP transaction and call performance.
  • SIP-CallerID: Retrieves and looks up SIP caller ID.
  • SIP Inspector: Written in JAVA, this software monitors incoming and outgoing SIP messages, and much more.
  • VoIPmonitor: An open source network packet sniffer for archiving, monitoring and troubleshooting quality of SIP VoIP calls.

Stacks and libraries

  • eXosip: An extended oSIP library which makes it easier to use the SIP protocol for multimedia session establishment for either VoIP or multiplayer gaming.
  • IvrWorx: VoIP prototyping and testing framework – high-level LuaInterface to SIP/RTSP/MRCP in order to test complicated VoIP networks.
  • Libre: Portable and generic library for real-time communications with a complete SIP stack with IPv4/v6 support.
  • MjSIP: JAVA-based SIP library for J2SE and J2ME platforms.
  • MSRP Library: Message Session Relay Protocol peer library and its relay extension written in Python.
  • NIST SIP 1.2: Series of SIP libraries, applications and tools in JAVA.
  • OpalVoIP: The Open Phone Abstraction Library is a C++ multiplatform, multiprotocol library for fax, video and voice over IP and other networks.
  • Open SIP Stack: SIP stack that includes ENUM, Presence (XMPP/SIMPLE) and NAT traversal. It comes with a platform agnostic stack implementation of RFC3261 so development can be done in various platforms, including Windows and Linux.
  • oSIP Library: Provides multimedia and telecom software developers an interface for initiating and controlling SIP-based sessions in their applications.
  • PJSIP: High performance SIP protocol stack written in C and with language binding for Python. It’s also customisable, portable and has a small footprint.
  • reSIProcate: SIP stack and sample application from SIPfoundry that works in various operating systems like Unix and Windows. Can be used for implementing proxies, instant messaging and gateways.
  • SailFin: Adds SIP support to the JAVA GlassFish application server.
  • SIP.js: JavaScript library for WebRTC and SIP signalling.
  • Sofia-SIP: A SIP user agent library and SIP stack implementation that includes support for STUN and presence.
  • Twisted: Protocol stacks and applications for Python with SIP support.
  • Vovida SIP Stack: An implementation of the SIP protocol for initiating voice calls over IP networks.
  • YASS: Stateful SIP stack used inYate and written in C++ that can be used for a proxy/server in a single or multi-thread model.
  • Yxa: A transaction stateful SIP stack written in Erlang.


  • Aheeva Contact Centre Suite: An open source PBX system for IP telephony. It offers call centre features such as call routing, contact management functions and research functions.
  • Asterisk PBX: An open source telephony engine and toolkit for building communications applications, such as IP-PBX and IVR systems, VoIP gateways and conference bridges. Also includes voicemail, call queuing and automated call distribution.
  • Bayonne:  A GNU project IVR server for users to easily integrate with telephony.
  • Elastix: Unified communications software that supports IP-PBX and IVR capabilities for IP telephony.
  • Evolution PBX: Asterisk-based PBX system that makes it easier and more cost effective to integrate existing phone systems with new VoIP systems.
  • FreePBX EcoSystem: An open source PBX platform for building robust and powerful communications solutions for businesses and call centres. Can be customised and adapted to your changing needs and run onsite or in the cloud.
  • Freeside CRM: Open source platform for VoIP, ISPs, hosted solutions, online businesses and service providers, with billing, CRM, automation and trouble-ticketing capabilities.
  • FreeSWITCH: An open source telephony platform for voice calls and chat. Can be used as a PBX system, media gateway and media server for hosting IVR applications. Also features voicemail, conferencing, recording, and more.
  • ICTDialer: An open source auto-dialler software that includes graphical IVR designer tools. It also supports voice, SMS and fax broadcasting.
  • jPBXLite: JAVA-based VoIP (SIP) PBX system that supports voicemail, voice conferences, call queues and an IVR system.
  • Kamailio: It’s also a high end, open source PBX system that supports instant messaging and presence.
  • Open PBX: PBX software platform for small offices and large call centres. Features include voicemail, auto-attendant and automatic call distribution. It can also be customised and extended with its highly compact Perl code.
  • OpenVXI: An IVR platform that implements VoiceXML, which is used to make IVR applications in PBX solutions.
  • OrecX: Available in both open source and open platform formats for recording, monitoring and replaying calls.
  • PBX4Linux: Software-based ISDN PBX platform with H.323 gateway for Linux.
  • SEMS: Free open source SIP express media server that has IVR capabilities.
  • SIP Witch: Pure SIP PBX call and registration server.
  • SipXecs: An open source SIP PBX for Linux with built-in IVR (voicemail and auto-attendant). The platform also comes with instant messaging, presence, and FreeSWITCH-based conferencing.
  • Sipwise sip:provider CE: A SIP-based VoIP soft-switch platform that can be used to build a variety of VoIP business models/systems, which include voice/video calls, conferencing, presence, voicemail and instant messaging.
  • snom ONE: Formerly pbxnsip, it includes IP-PBX and IVR platforms, along with a fax server, unified messaging, conferencing, outbound dialling, etc.
  • Switchvox: IP-PBX platform with call recording and visual voicemail.
  • Yate: Telephony engine that supports SIP and H.323. It offers open source PBX/PABX and IVR platforms, instant messaging, voicemail, VoIP, conferencing and call centre service.