Mumble - Mumble is an open source, low-latency, high quality voice chat software primarily intended for use...
Skype - Stay in touch with your family and friends for free on Skype. Download Skype today to chat and call on desktop and mobile.
Discord - Step up your game with a modern voice & text chat app. Crystal clear voice, multiple server and channel support, mobile apps, and more.
Digsby - Tagged makes it easy to meet and socialize with new people through games, shared interests, friend suggestions, browsing profiles, and much more.
RaidCall - Free & Light. Setting up is fast and easy; with no need to rent or set up servers. Low CPU usage and minimum memory footprint allows for smooth, uninterrupted communication. im. Group Communication.
Facebook Messenger - Facebook Messenger is a faster way to message.