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What You Need to Know About QoS on Virtual VoIP PBX

Posted by Randy Kremlacek on Sep 12, 2012 6:08:00 AM

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What is QoS?

qos quality of service hosted pbx voip

QoS stands for Quality of Service. It's a term you'll hear when people are talking about data network traffic optimization for voice. QoS is set of protocols and rules built into LAN routers and sometimes WAN switches, to prioritize network traffic and help ensure that the "most important" data gets through the network as quickly as possible.

QoS uses two primary functions when prioritizing traffic - classification and queuing. 

QoS Classification

Classification refers to how data traffic is identified and marked. Traffic can be classifed in many different ways. Streaming video, voice over IP, mission critical data are all common classifications. 

QoS Queuing

Queues are basically memory buffers in the router that stack up traffic that's been classified as less important compared to other traffic. Queuing's job is to know when to start allowing less important traffic to flow based on the traffic load and available bandwidth at that moment. 

Why is QoS Important for Voice over IP Networks? 

Data network protocols were never really built to transport voice very well. They were built to transport packets across networks in random order to make the most efficient use of network resources. The problem is that voice packets don't take kindly to getting broken up and being transported in random order. 

So, smart engineers came up with QoS that gives voice traffic high priority across data networks- including the Internet. 

QoS works by slowing down "unimportant" data packets down to allow more important traffic first access to precious bandwidth.

What's considered unimportant and important depends on how you configure your network. But for our purposes, consider voice packets important and regular data packets like your email or a web page download as unimportant.

By leaving room for important voice packets to reach their destination as quickly as possible, QoS enables a clear connection and a high quality voice conversation across the Internet.

QoS with Virtual PBX

Virtual PBX is your phone system in the cloud.

With Virtual PBX, the server that controls your phone calls, voice mail, call handling and etc. is located in a data center on the Internet instead of in your company's data closet. 

Because your phone call spends more of it's short life on data networks with Virtual PBX, QoS is more important than ever. 

Use of DiffServ Across Local and WAN Connections

DiffServ (Differentiated Services) is the preferred QoS networking framework for most modern IP networks. It operates on the principle of traffic classification to provide high priority, and thus low-latency to critical network traffic such as voice or streaming media.

In other words, DiffServ doesn't automatically identify your voice packets. A network engineer must tell DiffServ which types of traffic should receive special treatment. This is usually done with Level 3 header data. Once configured on each router or switch on the network, each traffic class can be managed differently, ensuring preferential treatment for higher-priority traffic on the network.

As a Bay Area Hosted PBX provider, TeleDynamic tries to employ QoS in as many parts of the network that we can control - namely your Local Area Network (LAN) and the ISP's circuit to the Internet. 

 Resilient Voice Architecture - TeleDynamic

About the Author

Randy Kremlacek

President | Head Chef

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Randy Kremlacek is president and Head Chef of TeleDynamic Communications, and is a Digium Select Partner and 2013 Pinnacle Award winner. TeleDynamic Communications provides turnkey premises-based PBX and hosted PBX, SIP Trunking and Unified Communications. Randy Kremlacek prides himself on knowing the telecommunications industry as well as he knows his way around his own kitchen. READ MORE

 

 

Randy Kremlacek

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