Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.

Everleagues - Everleagues is a cloud-based application that offers team communication, file sharing and storage, data tracking, and activities management.

Slack - A messaging app for teams who see through the Earth!

Stork.ai - AI-Based Collaboration for Hybrid Teams. Rich media messaging, advanced video and voice conferencing, auto-transcribing and screen sharing. Serendipitous meetings at the water-cooler with your human and AI teammates.

Cisco Jabber - Cisco Jabber lets you access presence, instant messaging (IM), voice, video, voice messaging, desktop sharing, and conferencing.

openmeet - Account free video conferencing with a rooms component that lets you use VC within a physical meeting room. The server can also be hosted in your own cloud for extra privacy/security.