QoS Control for VoIP
VoIP Network Management
Unlike the PSTN network, VoIP uses the same Internet connection as the rest of your residence or business. The traditional telephone system relies on a network technology known as circuit switching. This essentially means that when two people are talking to each other, the line between them is reserved for them alone. It doesn't matter what the rest of the network is up to. This ensures a constant and stable connection no matter what. The flipside to this is that such a system is incredibly wasteful. Between 50 to 80% of the time spent talking to another person consists of silent intervals. If that circuit is not being used during that time, it's incredibly wasteful.
The IP network makes use of something called packet switching. Packet switching allows multiple applications to utilize a line at the same time. This means that you can browse the web, listen to music, and download a file all at once. Yet as everyone knows, too much of this can cause congestion and slowdowns for everyone involved. Normally this might not be a big deal since web browsing is not real-time. Even YouTube videos can offer their content to compensate for any network delays that the video stream might encounter along the way.
Unfortunately, VoIP is a real-time protocol. That means even a delay of a few tens of milliseconds can cause a noticeable degradation in the quality of communication. This means that we need special protocols and infrastructure to handle VoIP traffic as compared to the rest of the Internet. This is largely achieved by the implementation of QoS or "quality of service" rules that are implemented on various routers along the way.
QoS for VoIP
A lot of hardware these days comes equipped with inbuilt rules for giving preferential treatment to real-time P2P protocols such as VoIP and gaming. However, if you want to be doubly sure, you can craft their own rules by entering your router settings and ensuring that the proper prioritization is being given to VoIP. Many routers like those provided by Cisco have advanced VLAN configuration settings that automatically creates a separate virtual LAN VoIP traffic thereby isolating it from excessive bandwidth consumption of other applications. This means that no matter how much bandwidth a file download is taking up, VoIP will always be guaranteed to have a certain amount reserved for itself.