How Much Bandwidth Does VoIP Use Per Call?

Published In

Voice over Internet Protocol calls, or commonly known as VoIP calls have gradually become one of the most preferred substitutes of the traditional landline phone calls in recent times. Enterprises, across the globe, are adopting it for their communication needs as it comes with a variety of advantages like flexibility, cost-effectiveness, and easy initial setup, etc. However, how much bandwidth does VoIP use per call is a question that you must get an answer to before implementing a VoIP system in your organization as it helps in evaluating the requirement of internet speed for handling a large volume of calls.

What is bandwidth and why it matters?

As a user, you might have experienced buffering in online streaming platforms or call drops on your video calls, if you are using too many applications at the same time which use the internet. The reason is perhaps that you are using an internet connection that is not top of the range and has a lower bandwidth. You can easily understand bandwidth as the rate at which you can transfer a certain amount of data during a certain period over your internet service.

ISPs or Internet Service Providers provide packages for different bandwidths which give different data transfer speeds and thus affect the internet experience. Since VoIP calls are entirely made over the internet hence bandwidth plays an important role as the quality of the call depends on the internet speed. In the case of a basic internet package, the bandwidth is typically kept low and there are chances that you experience frequent call drops in case there is a large number of calls are made at the same time. Here are some of the basic parameters to determine what bandwidth would be appropriate for your organization’s VoIP system:

  • Number and type of applications and services that run over your internet connection at the same time
  • Upload and download speed of your internet connection package
  • Type of internet connection – whether it is 4G LTE or 5G
  • Devices and users connected over your organization’s network
  • VoIP optimization settings (Quality of Service or QoS settings) that your internet connection supports to prioritize voice traffic

How much bandwidth is needed for VoIP?

Before assessing how much bandwidth would be required for your firm’s VoIP system, it is important to understand how this works and what the key contributors to bandwidth utilization are. Here they are:

Simultaneous calls

The thumb rule to determine the bandwidth is the number of simultaneous calls you are making. The higher the number of calls, the higher would be the bandwidth requirement for the internet connection. If you are making 3 concurrent calls, the minimum bandwidth requirement comes as 300 kilobytes per second. For a smooth experience, the recommended internet bandwidth is 3 megabytes per second for upload and download both. The bandwidth requirement increases in the same proportion basis the number of calls you need to make at the same time.

Quality of sound

The sound quality that your VoIP application provides also determines the data utilization of your internet connection. Superior the sound quality, higher would be the data utilization. VoIP applications use a codec program that converts speech signals into digital data which is further transmitted over the internet during the VoIP call. Popular applications like FaceTime and Skype use G.729 codec for speech to HD data conversion. Since these applications are mostly used over the mobile data network, hence G.729 codec applies a compression algorithm for the bandwidth optimization. Typical utilization for this codec is around 30 megabytes per hour. However, a widely used codec for business VoIP systems is G.711 which doesn’t compress the voice data. Since organizations use high-speed leased lines for internet services which typically have a flat tariff. The quality of sound for customer calls becomes the priority over bandwidth optimization in such a scenario. Typical utilization for this codec is around 78 megabytes per hour.

Audio v/s Video calls

Needless to say that video calls need significantly higher data in comparison to audio calls as they also send video data along with voice data over the internet connection. Typical variables that affect bandwidth are screen size and quality of the video. A video call between two mobile devices uses about 200 to 225 megabytes per hour of data. If the call is placed between a mobile and a computer then the data utilization increases to 260 to 275 megabytes per hour. Similarly, an SD call uses approximately 190 to 200 MB of data per hour whereas this utilization increases up to 1.2 GB per hour in an HD call.

How to determine your functional bandwidth?

It is always good to know what your internet connection’s bandwidth is. There are different packages provided by internet service providers however speed mentioned on those packages is the maximum limit and you seldom get that kind of internet speed in reality. There are portals and apps available which help you determine the upload and download speed of your internet connection. These services are available free of cost. You can easily perform a throughout test on these portals or apps to determine your internet connection’s functional bandwidth. Some of the popular websites are speedtest.net and fast.com.

The results may vary every time you run the test as it depends upon what bandwidth all the applications running on your system are utilizing at a given point in time and from where you are performing the test. This is to note that upload speeds are typically lower than download speeds; hence it is advised that you should carefully match your requirement with the lower number so that there are no bandwidth challenges at a later stage. Also, as mentioned earlier, the packages provided by the ISPs show the maximum bandwidth hence it is recommended to keep at least 5x buffer while estimating the bandwidth requirement.

Calculating the bandwidth you need?

There is a pretty simple method to calculate your organization’s bandwidth requirement. All you need is to have the number of users who would be making calls at the same time. One user typically utilizes 100 kbps bandwidth. If 50 users would be making simultaneous calls, the total bandwidth utilization becomes 5000 kbps (50 x 100 kbps) or 5 Mbps. As recommended above, you need to keep the safety margins as there would be other applications also that would be running over your internet connection. Keeping a safety margin of 5x, the total bandwidth requirement comes out as 25 Mbps for 50 simultaneous users. You can use the following formula for your ready reference:

  • Bandwidth Requirement: Number of simultaneous Users x 100 kbps x 5 (safety margin)

You can increase the safety margin basis the other services and applications that are being run over your system. This varies from organization to organization.

Quality of Service and VoIP phone systems

If you have estimated your bandwidth requirement correctly, it should always be sufficient to make high-quality calls over your VoIP system. You can also run a VoIP capacity test of your system on phone.com. This helps you assess the performance of your network by making concurrent calls. However, if you are using other applications on the system that uses the internet, there are chances that the quality of your VoIP call may drop. In such a case, you can reconfigure the QoS (Quality of Service) settings on the router (if your router supports it). Through this, you can easily prioritize voice call data over your data network and enhance the quality of your VoIP calls. It does not let other applications impact the call quality. In case you face difficulty adjusting the QoS settings on your router, you can anytime connect with your ISP for further information. Typical settings are as follows, however, you should check your router specific settings:

  • High Priority on UDP/5060, UDP/6060, and UDP/16384 to UDP/32768
  • Disable the ALG (Application Layer Gateway) function of the router
  • Disable the SPI (Stateful Packet Inspection) function of the router

These are some of the standard settings; however, you must consult a data network expert before you change any of the default settings of your router.

Conclusion

If you had doubts regarding the bandwidth requirement for your VoIP systems, we hope that by now, this article has answered this question – how much bandwidth does VoIP use per call. From the advent till today, the internet has revolutionized the way the world operates in almost all fields and VoIP telephony is surely one of them. It is flexible. It is cost-effective. It is simple to set up. It is the thing today. And with high-speed internet services available today, organizations can easily depend upon VoIP for their communication requirements.