The best free alternative to 3CX is Asterisk, which is also Open Source. If that doesn't suit you, our users have ranked more than 25 alternatives to 3CX and many of them is free so hopefully you can find a suitable replacement. Other interesting free alternatives to 3CX are FreePBX, FreeSWITCH, YakYak and Yate - Yet Another Telephony Engine.
Asterisk is an open source framework for building communications applications. Asterisk turns an ordinary computer into a communications server. Asterisk powers IP PBX systems, VoIP gateways, conference servers and other custom solutions.
FreePBX is a web-based open source GUI (graphical user interface) that controls and manages Asterisk (PBX), an open source communication server.
FreeSWITCH is a scalable open source cross-platform telephony platform designed to route and interconnect popular communication protocols using audio, video, text or any other form of media. It was created in 2006 to fill the void left by proprietary commercial solutions.
Yate is a softswitch (concept of separating the network hardware from network software).
Wazo is mainly an IPBX that provides communication services such audio, video, and instant messaging based on the use of standard network technologies such as the TCP/IP protocol. It is interoperable with most market telephony systems and gives users access to flexible and...
Instant messaging with voice and video options, live group video chat for up to 10 participants, public and private rooms, interest communities, mobile and desktop access, user-created rooms, moderation tools, and options for anonymous participation.
Kamailio® (successor of former OpenSER and SER) is an open source SIP server released under GPL, able to handle thousands of call setups per second. Among features: asynchronous TCP, UDP and SCTP, secure communication via TLS for VoIP (voice, video); WebSocket support for...
Spreed is the worldwide unified web conferencing service offering integrated web and telephone conferencing. It is based on Flash Player. Free service includes 3 attendees and max 1.5h meetings. Single events or monthly service can be purchased.
XiVO is an IP-PBX, a unified communications platform that connects phones on a local or private network with other networks such as public landlines and mobile telephones.
VoipStunt is a free program that uses the latest technology to bring free and high-quality voice communications to people all over the world. When you use the free VoipStunt software, you can call regular phones in various popular destinations for free or call at an incredible...
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YakYak is a client for Google Hangouts, while 3CX is a VoIP call center system