freepbx - FreePBX is a web-based open source GUI that controls and manages Asterisk (PBX).

Zoom - Equip your team with tools designed to collaborate, connect, and engage with teammates and customers, no matter where you’re located, all in one platform.

Asterisk - An open source telephony switching and private branch exchange service for Linux.

GoToMeeting - GoToMeeting is a web conferencing service offering a range of services which are available on Mac, PC, iOS and Android devices.

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.

WebEx - Cisco WebEx Web Conferencing, Online Meetings, Desktop Sharing, Video Conferencing