Telefonie
- Skype - The whole world can talk for free.
http://www.skype.com/
Our software’s quick and easy to get started with. Download, register, install, plug in your headset, speakers or USB phone and start calling your friends. The calls have excellent sound quality and are highly secure with end-to-end encryption. You don’t even need to configure your firewall or router or any other networking gear. It just, you know… works. - Discord
https://discordapp.com/
All-in-one voice and text chat for gamers that’s free, secure, and works on both your desktop and phone - Free Call
http://www.freecall.com/
Free phone calls with the FreeCall. Call your online friends for free as well as a special selection of popular international destinations. - Mumble, the open source VoIP solution
https://www.mumble.info - Net2Phone -- Communication without borders
http://web.net2phone.com/ - TeamSpeak
http://www.teamspeak.com
TeamSpeak is software for quality voice communication via the Internet - Ventrilo - Surround Sound Voice Communication Software
http://www.ventrilo.com
Voice communication over the internet. - Voipbuster - The Free Calls Company
http://www.voipbuster.com/
Free phone calls with the VoipBuster. Call your online friends for free as well as a special selection of popular international destinations.