What is QoS in business telephony and how does it work
By Natália Mrázová
| 4. January 2022 |
Business Phone SystemPhone system
By N. MrázováNatália Mrázová
| 4 Jan 2022 |
Business Phone SystemPhone system
    By N. MrázováNatália Mrázová
    | 4 Jan 2022
    Business Phone SystemPhone system

    What is QoS in business telephony

    what is QoS in business telephony MAIN

    What is the biggest worry for businesses that are considering starting to use Voice over Internet Protocol (VoIP) instead of traditional analog phones? The quality of calls made through the internet. Landlines were once the most reliable communication method out there, but they are not anymore.

    Almost the only thing businesses had to worry about when using landlines were technical issues that caused their entire phone systems to malfunction. 

    VoIP, meanwhile, relies on an internet connection. Depending on the state of the network, it’s, therefore, possible to experience either crystal clear and smooth calls or several unpleasant issues such as jumbled sentences and constant buffering. The latter is not something you want to deal with during important business calls. Fortunately, there’s a way to significantly improve the stability and clarity of your VoIP calls so that they can be made even during heavy network traffic. Enter Quality of Service (Qos).

    What is it and how does it work? Read on to find out.

    What is Quality of Service?

    QoS refers to any technology that manages, orders, and prioritizes types of data packets to guarantee that those with the greatest importance will be transmitted before all others in order to help reduce packet loss, jitter, and latency. Why is this important?

    Why do I need QoS?

    During a regular workday, multiple employees use the same internet connection for different work-related tasks and personal reasons. You most likely also have dozens of devices connected to the internet at any one time. If everyone starts to use the internet simultaneously or there’s someone on the connection using up a lot of bandwidth (let’s say, updating databases), the network can get pretty crowded. 

    What might happen if you tried to start a regular or video call during that time? You may have to deal with the video buffering every few seconds, listening to jumbled-up sentences, or not even hearing a sound. And that’s assuming you even manage to get connected to the recipient at all.

    A Typical QoS Process 

    To smoothly manage incoming network traffic and quickly find out what’s in each data packet, QoS systems have several in-built tools with specific functions:

    • Classification and marking examines the type of data inside each packet, classifies them, and marks them according to their priority.
    • Shaping finds and prioritizes real-time data packets such as voice and video conferencing over other data types.
    • Queueing identifies each data packet’s markings, puts them into different types of queues, and reserves bandwidth for them. Those that are not high priority are put into a buffer to be sent later.

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    What causes call quality issues?

    All of the problems with VoIP calls are related to one thing – namely, how routers handle data packets in the network. During calls, VoIP converts sound into data packets and sends them via the internet to the recipient. Once they arrive, these packets are unpacked and converted back into sound so that the recipient can hear the speaker’s voice. And here’s exactly where the problem lies.

    By default, routers accept and pass forward packets using a “First in, First Out” method. This means that the first packet to arrive at a router is the first to be transmitted or unpacked. But with video conference or VoIP calls, this method sometimes fails to work.

    All types of data have equal priority with FIFO, so they will be forwarded on in the order the router receives them. This is regardless of whether the data are email messages or audio. But while you probably wouldn’t even notice if you received an email one or two minutes late, every millisecond counts for video conferences or VoIP calls. If the network is overloaded and your voice packets arrive later than they should or are dropped along the way by the router, it can make continuing a conversation outright impossible.

    How does QoS work?

    Here’s where Quality of Service comes in. What it does is basically a form of traffic management of various data packets traveling across a network. First, QoS marks packets based on their type or destination route and then creates separate queues for them based on their importance. Then, when data packets pass through the router, it can understand what is inside each one, put them into queues, and then send them in priority order.  

    Let’s say you set the system to prioritize all packets related to audio or video calls. When you start a video call, the QoS system will then put all packets containing audio or video data at the front of the queue in order to minimize any possible issues caused by heavy network traffic. This, in turn, helps to ensure that conversations can flow without any interruptions.

    Benefits of QoS 

    If you find that you and your employees are constantly experiencing delays or hiccups with your internet connection that make several applications barely usable, then implementing QoS to prioritize data will be of massive help. Your most critical applications can still have the resources and speed they require during times of heavy traffic, while less important applications will be put into a queue to wait for access to the network later.

    QoS can also save your money by allowing you to use your existing technology more efficiently. It helps to solve several to solve many problems that often plague businesses, such as:

    • High latency – the lower the time it takes for a packet to travel from the source to the intended address, the better. Anything below 150 ms is acceptable, but a latency of even 300 ms or more can make VoIP unusable. By using Priority Queuing, QoS can minimize the latency for essential applications or packets and ensure they are sent at regular intervals. 
    • High Jitter – another sign of heavy network traffic that occurs when packets are unpacked in the wrong order. As a result, you might hear gaps in conversation or only unintelligible sentences. If jitter levels are above 30 ms, this can severely degrade the quality of calls and cause a VoIP service to be unstable.
    • High packet loss – exactly what it says on the tin, which is when a router does not accept more packets because the network is overloaded. With QoS in place, all incoming data packets are categorized and either sent straight away or put into a buffer to be sent later rather than dropped.
    • Suspicious traffic clogging the line – thanks to identification and classification features, QoS also can protect companys’ networks from worms, viruses, and DDoS attacks by spotting any suspicious traffic and blocking it in order to minimize the effect on the network.

    And as an added benefit, QoS gives you more control over how your network operates. Combined with proper network monitoring, You can quickly set up the types of data and applications that are given priority access to the internet and keep an eye on the bandwidth used in your company, without having to be tech-savvy.

    Is QoS in every VoIP provider the same, though?

    If you look at the number of companies offering VoIP systems, you might wonder if every provider offers the same or similar levels of QoS. The short answer is no. 

    While in theory all VoIP providers offer similar things, they have vastly different levels of call quality and platform reliability. We therefore recommend checking and comparing the average QoS metrics for each provider before picking a VoIP platform.

    We regularly examine our VoIP platform for Quality of Service metrics to ensure we can provide the best possible call quality. Based on the most recent tests, performed in December 2020 over 35 days, our average latency was 23 ms and average jitter was 17.8 ms. We also monitor call quality metrics in real-time, and if they drop below a certain level the call route will be automatically changed to another server without impacting the conversation.


    If you want to regularly make calls through VoIP or rely on video conferencing, then using Quality of Service is necessary. It can prevent the most frustrating call quality issues from happening while you are making important business calls, and help your business to manage your network much better. It only takes a couple of minutes to set up CloudTalk QoS in your business. You can then rest easy knowing that your most important applications will have priority access to bandwidth whenever they need it, even during peak hours.