Apps with 'Audio Calling' feature
TeamViewer lets you establish a connection to any PC or server within just a few seconds.
Secure, fully featured, and completely free video conferencing.
The goal of Gajim is to provide a full featured and easy to use XMPP client. Gajim works nicely with GNOME, but does not require it to run.
Zoho Cliq simplifies your team communication with organized conversations, information that's easy to find and by connecting to the tools you love.
Cost-free, easily usable, secure, open source platform for video calls using WebRTC technology.