Many of the features of the VoIP such as Video support, Mobile Apps, WebRTC Support can be implemented by using the Asterisk. Features include:- CentOS 6.4 and your choice of Asterisk 1.8, 10, or 11 with FreePBX 2.9, 2.10, or 2.11. All versions include Google Voice for free calling throughout http://johnnyikkk05161.blogvivi.com/1141892/asterisk-the-future-telephony-feature-and-security-concerns