Asterisk - An open source telephony switching and private branch exchange service for Linux.
Leadfeeder - Leadfeeder converts your website visitors into sales. Connect your website's Google Analytics to Leadfeeder and unlock the power of seeing who`s visiting your site!
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.
Visitor Queue - Better identify the companies that visited your website!
Wazo.io - The UCaaS Platform Built for MSPs
Elucify - A completely free software tool that uses crowdsourced data to find business email addresses