Asterisk - An open source telephony switching and private branch exchange service for Linux.
FreeSWITCH - FreeSWITCH is an open-source media application designed to support popular protools such as SIP and WebRTC and provides a platform to develop voice and video applications.
freepbx - FreePBX is a web-based open source GUI that controls and manages Asterisk (PBX).
Wazo.io - The UCaaS Platform Built for MSPs
VitalPBX - VitalPBX is a full-feature PBX (phone system) based on Linux and Asterisk.
XiVO - XiVO, première solution de téléphonie d'entreprise ToIP Open Source. TPE/PME Grande Entreprise / Centre de contact / Secteur Public. Contact: 04 37 49 78 10