Asterisk - An open source telephony switching and private branch exchange service for Linux.
Noor - Chat like you're in the office together
Wazo.io - The UCaaS Platform Built for MSPs
Schoox - Schoox offers the modern learning and knowledge management system for organizations.
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.
Quizizz - Quizizz is a multiplayer quizzing game.