CloudTalk - Work locally, grow globally
Tox - Send messages, files, create groups and make Tox to Tox audio and video calls. Securely.
Aircall - Aircall is a call center software of a new generation designed for fast growing companies. Setup instantly and integrates to your CRMs
qTox - A Qt graphical user interface for Tox.
Skype - Stay in touch with your family and friends for free on Skype. Download Skype today to chat and call on desktop and mobile.
Signal - Fast, simple & secure messaging. Privacy that fits in your pocket.