Calls on Slack - Make voice calls in Slack
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.
Pingly - Your communication hub — Email, text & voice in one app
Whiteboard for Skype Interviews - Skype brings a whiteboard to Skype Interviews
HandsFree 2 - Call and SMS in Mac using your Android phone via Bluetooth
Missive - Team communication app now supporting FB, Twitter & SMS