Mitel - Business Communications and Collaboration
Skype for Slack - Move your slack discussions to a group skype call
Google Voice - Google Voice gives you one number for all your phones, voicemail organized in an email format, free...
Aircall Now - Make voice calls inside Intercom Messenger 📞💬
Phonebooth - Phonebooth is one of the leading voip providers, providing phone systems & phone service for small businesses.
Slack - A messaging app for teams who see through the Earth!