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.
Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
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.
WhatsApp - WhatsApp Messenger: More than 1 billion people in over 180 countries use WhatsApp to stay in touch with friends and family, anytime and anywhere.
FusionPBX - FusionPBX is an open source FreeSWITCH GUI.