From Hammer & Chisel Inc.:
Discord is all-in-one voice and text chat for gamers that's free, secure, and works on both your desktop and phone. Discord is always completely free to use with no gotchas. This means you can make as many servers as you want with no slot limitations. Encrypted server to client communication keeps your IP address safe. Stop getting ganked because you're logged into Skype. Our resilient Erlang backend running on the cloud has built in DDoS protection with automatic server failover. Easily share images, videos, and links from your desktop or phone. Discord embeds most types of media directly in the chat.