The telephone network has always been fault-tolerant and highly reliable. You could always count on being able to make a call and not get dropped while you’re connected. But with the advent of cellular and VoIP, some in the industry became a bit complacent because it became somewhat acceptable to drop a voice call and redial. While this may be okay for some voice calls, it is not okay for critical functions such as video surveillance, firewalls, denial of service (DDoS) mitigation solutions and network controllers. Network Functions Virtualization aims to virtualize every network function.