Slack - A messaging app for teams who see through the Earth!
Google Voice - Google Voice gives you one number for all your phones, voicemail organized in an email format, free...
Skype - Stay in touch with your family and friends for free on Skype. Download Skype today to chat and call on desktop and mobile.
VoIP.ms - VoIP.ms is a VoIP origination and termination tool.
Microsoft Teams - Microsoft Teams provides the enterprise-level security, compliance and management features you expect from Office 365, including broad support for compliance standards, and eDiscovery and legal hold for channels, chats, and files.
Mitel - Business Communications and Collaboration