What is QOS (Quality of Service)?

VoIP phone systems offer huge advantages to businesses, but there are a few things to take into consideration in order to get the most out your investment.

Whenever you use the Internet to make and receive calls, like how VoIP phone systems do, it’s important to consider the requirements and possible pitfalls.

For starters, your internet connection only has limited capabilities. You may have noticed with your home internet that if you stream video, browse the web, download files, and do other internet-heavy tasks, your internet speed can start to drag.

The same is true for your business internet.

When you have too much “traffic” on your business network (videos, downloads, email, etc.), it can slow your connection down. This is particularly bad news if your business phone system is being ran over the internet, because it can lead to poor call quality and dropped calls.

That’s where QOS helps.

QOS (which stand for Quality of Service) can prioritize network traffic to make sure your phone system has priority over everything else so you can make a phone call regardless of what anyone else is doing on your network (streaming video, downloading large files, etc.)

QOS ultimately works to ensure that your customers are taken care by making sure your call quality doesn’t suffer and your phone calls aren’t being dropped.

Let’s look a little more at how you can get the most out of your business phone system using QOS.

Call to ActionWant to see if your network is ready for VoIP? Check out our free VoIP Network Test tool Test My Network

Understanding Bandwidth and Quality of Service - Digium Phones VoIP Image

Understanding Bandwidth and QOS

Bandwidth is what carries data from your network equipment to your phones and allows you to make calls. If you don’t have enough bandwidth to support your calls (and other internet traffic), as we mentioned, it can lead to poor call quality and dropped calls, which ultimately lead to frustrated callers and customers.

So it’s easy to see why bandwidth is the most important aspect of your VoIP phone system setup. Making sure you have enough bandwidth and making sure that bandwidth is being properly allocated are two critical consideration for your phone system’s success.

How much bandwidth do I need for a VoIP phone system?

Use the following simple equation to determine the necessary bandwidth to support your calls:

VoIP Bandwidth - Number of Concurrent Calls Image

(number of concurrent calls at your company’s peak)


VoIP Bandwidth - 100kb per Second Image

100 kilobits per second


VoIP Bandwidth - Bandwidth Image

bandwidth in Megabits per second (Mbps) needed for calls

The average phone call takes about 100 kilobits per second, so multiply that times the maximum number of calls your business typically makes at one time. That will give you the bandwidth required for your phone calls. Now you need to add in the bandwidth you use for email, video, etc. and that will give you your total bandwidth that you need.

Call to ActionWant to see if your network is ready for Unified Communications? Download our free guide Download

How QoS Prioritizes and Improves Your VoIP Calls

With an unmanaged switch (typically, a consumer-class switch) all network traffic is sent as it is received. In other words, all traffic is basically treated the same.

So if one person is sending a large video file over your network or server, then they’ll be using up a large portion of the available bandwidth for that application. If someone later picks up the phone to make a call, this call (your voice traffic) will also be transmitted on the same network pipe as the video file. In this example, the large video file could starve out other applications, such as voice.

This is why voice calls will sometimes sound great, and why at other times they sometimes sound horrible.

Improve VoIP Calls with Quality of Service - VoIP Image

This is when QoS comes in and helps.

Networks are capable of using Quality of Service (QoS) to prioritize the most important traffic types. So in our example above, the voice traffic will then take priority over the data traffic. Sure, this may slow the data transfer down, but at least you won’t miss out on any part of your voice call – it will sound crystal clear and you will still be able to transfer all of your data.

When voice quality fluctuates like this, installing QoS-capable switches and routers are the most important first steps to fixing the problem.

Switchvox Solutions - Network Equipment and Voice Quality Image

How Your Networking Equipment Affects Voice Quality

The kind of networking equipment you are using is critical to having a good quality phone conversation.
For example, a business-grade router can make a significant difference in call quality and reliability. A router is like the traffic cop for your network because it makes sure all the activity on your network is being routed to the right place.
In order to get features like QOS and others to make sure your traffic is directed in the right direction, you’ll need to have a business-grade router.
Companies with fewer employees typically have fewer networking requirements, so they will have an easier job of choosing networking equipment. For example, if your company is a small retail store with a few phones and a couple of Point of Sale (POS) terminals with no desktop computers, then you won’t be transmitting a significant amount of data.
Because they usually have fewer users and less simultaneous voice, video and data traffic, they can shop based more on price than robust capabilities.
Most data networks of any class are equipped with enough bandwidth and resources to handle simultaneous voice and data traffic. However, if you have many active computer users, all of which are sending and receiving large video files, actively using email, watching videos, and more, then you’ll want networking appliances equipped to prioritize and process all of this simultaneous traffic.

To learn more about networking equipment and Unified Communications, download our guide Determining Network Readiness for Unified Communications.

Chat Now

Contact Us

Switchvox Cloud - Hosted Phone System

Prefer a monthly subscription
Managed in the Cloud

Learn More

Switchvox On-Premises IP PBX

Prefer a capital expense
Managed on-site

Learn More