VOIP Bandwidth Consumption

“How much speed do I need to make a voice call?”

That’s a common question asked in forums and Q&A sites. There is just one small problem with it, which is that the term “speed” is not accurate. The question should be, “How much bandwidth does my internet connection need?”

Bandwidth and connection speed or internet speed are used interchangeably by ISPs and consumers. Though they are not the same thing, they are related, and this relationship will determine the quality of your VoIP calls. There are certain VoIP bandwidth requirements that need to be met in order for a VoIP phone system to be operable. Let’s take a closer look at how bandwidth and internet speed work together to give you or your business the best VoIP quality.

What is Bandwidth?

Webopedia defines bandwidth as a range within a band of frequencies or wavelengths. Bandwidth is also defined as the amount of data that can be transmitted in a fixed amount of time. It is measured in bits per second(bps) or bytes per second.

Bandwidth indicates the maximum amount of data that can pass through a channel. More bandwidth means more phone or internet data can pass through it. Speed is the rate at which data passes through the channel in a given unit of time.

A common analogy is of a water pipe.

The larger the diameter of the pipe (bandwidth), the more water that can flow through (i.e. data) at a specific speed.

Another aspect to consider is bandwidth usage. If you are the only one who is using the water pipe, then you get the benefit of that speed. But as soon as some other tap is opened, so the bandwidth usage is shared, the speed with which the water flows to you will drop even though the total capacity of the pipe remains the same, as does the speed with which the water is flowing through it. As more people start to draw water from the same pipe, the rate at which you get the water will drop even more.

However, more bandwidth does not mean more speed; even if you double the width of the pipe, the speed of the water will remain the same. Along the same lines, speed does not slow down when there’s more bandwidth usage.

How Does Voice Calling Use Bandwidth?

Voice calling through VoIP needs high bandwidth. One of the areas where traditional PSTN (public switched telephone network) wins over VoIP phone calls is voice quality. If the optimum bandwidth is not available due to high bandwidth usage, then quality drops. Latency issues and other network overheads also play a role in voice clarity.

Also, VoIP phone systems use codecs to convert an analog voice signal to a digitally encoded version. Codes compress and decompress voice data and help it to travel over the internet more efficiently. These special algorithms are designed to balance bandwidth requirements with the desired audio quality even at times of high bandwidth usage. Codecs that provide better quality need more bandwidth.

To know bandwidth consumption or bandwidth usage for any call, it’s important to know the codec used. Here’s a list of codecs and the amounts of bandwidth each need.

As you can make out from the CISCO voice codec bandwidth calculations, each codec is different from the other based on compression algorithm, platform support, bandwidth, and data rates, etc. The use of the codec depends on the application as each has its own pros and cons.

How Does Bandwidth Usage Work in the VoIP Apps You Use?

Skype offers high definition voice and video calls. So, its bandwidth requirements are high. WhatsApp asks for much less bandwidth – much lower than an HD YouTube video. But it is slightly more than other popular VoIP apps such as Nimbuzz, Zangi, Viber, and Line.

If we take two common VoIP apps like WhatsApp and Skype…

  • WhatsApp implements WebRTC technology and the Opus codec. The minimum requirement for a WhatsApp call is 64 kbps.
  • Skype used the SILK codec and then had a hand in developing the Opus codec. The minimum requirement for an HD video call is 1.2 mbps while a group video call of 7+ members can go up to 4mbps.

WhatsApp is designed for the mobile user on the go, while Skype is for the business user on his desktop. The end-user consideration plays a role in the codecs used and the minimum bandwidths supported.

Yes, codecs are important. But not in your control. Bandwidth consumption depends on the software used and the prices offered by your ISP. This is where you will have to decide for residential or professional use. Ask yourself this question first…

Do You Have Enough Bandwidth for VoIP?

Calculating optimum bandwidth can be a daunting task. For residential use, you can take a shortcut. When all other factors are stable, 90-100 kbps (kilobits per second) is minimum for good quality call. Of course, if there are many concurrent callers on the same network, you will need more bandwidth. For five callers – 512 kbps should be the minimum yardstick.

The number of simultaneous VoIP calls also depends on the bandwidth available for VoIP use. All kinds of internet browsing can share a slice of this bandwidth pie. Also, internet speeds seesaw through the day.

Test Your Bandwidth with Simple Math

A few rules of thumb and simple math can help you calculate your residential bandwidth.

Use a good bandwidth measuring tool like SpeedTest.net to gauge your download and upload speeds. For best results, do several tests at different times of the day. Upload speeds are lower than download speeds. Your lowest upload speed is the minimum limit of your connection and is a good benchmark to put your VoIP needs against.

Multiply your upload speed by 1000 to convert from mbps to kbps. Skip this if your speed is already expressed in kbps.

Each VoIP call commonly needs 100 kbps up and down. Multiply the number of expected parallel calls by 100 kbps. So, three people in your family, all on calls at the same time, will need a minimum of 300 kbps up and 300 kbps down.

This will tell you if your bandwidth is enough to support everyday VoIP. As your family will also be using the web for other tasks, always factor in extra bandwidth to avoid congestion.

You can also put bandwidth calculator apps to use. These five apps are free for the web, iOS, and Android:

Small and medium businesses can use free but advanced online bandwidth calculators to find the benchmark necessary to handle a specific number of VOIP calls with any audio codec.

Have You Checked Your Broadband Consumption?

Thanks to broadband penetration, most connections can easily support a dozen concurrent VoIP calls at home. A SpeedTest.net report from August 2016, reported an average download speed of 50mbps and upload speed of 19 mbps for fixed broadband lines in the U.S. Just like any other essential service, you get what you pay for. A high-speed business connection should be sufficient to handle your professional VoIP needs.

Your business may also rely on cloud collaboration and other bandwidth-hungry activities, such as online video conferences. Do a bandwidth test to see if your network can handle all activities without causing congestion. If it can’t, re-evaluate your internet plan or switch ISPs. Shifting the VoIP to another dedicated connection is a practical solution.

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