How many VoIP Phones can my internet connection support?

Open and run a Speed Test.

Look at the two numbers on your speed test: The Download Speed and Upload Speed

Take whichever number is lower (typically the upload speed) – we’ll call this your bandwidth speed. Now match your bandwidth with the number in the chart below: 

VoIP Speed test: How to do the math

If you want to find the exact number of lines you can support, here’s how it works:

  • First take your upload speed and multiply it by 1000. This is to convert it from Mbps to Kbps. For example, 11.99 Mbps = 11,990 Kbps. If your speed is already expressed in Kbps, leave it as is.
  • Now divide this number by 445. This will tell you the recommended number of phone lines your connection can support. For example, 11,990 / 445 = 27 VoIP phone lines.
  • To find the maximum number, take that same number and divide it by 100. This is how many phone lines you can support in a perfect world, if your connection speed were to be completely steady and if you weren’t using your internet for any other activities, like internet browsing or downloading.

Maximum VS Recommended number of lines: What's the difference?

The number of VoIP lines you can support doesn’t just depend on your internet speed. It also depends on how much of your bandwidth is used up by other things, like internet browsing, email, online software, web-based POS systems, etc.

Our recommended number of lines takes into account these other browsing activities, as well as natural fluctuation of internet speed throughout the day.

The maximum number of lines you could support if your connection is used exclusively for VoIP, and your internet speed is consistent. Cable internet speeds tend to fluctuate, whereas newer fiber connections are more reliable.

What do the VoIP speed test numbers mean?

  • Upload Speed – The upload speed shows the upload capability of your connection, measured in megabits per second (Mbps). Because this number is typically lower than your download speed, this reflects the actual bandwidth available to your computer.
  • Download Speed – shows the download capability of your connection. It’s the maximum amount of data your connection can receive, measured in megabits per second (Mbps). As long as your upload speed is lower than your download speed, you can ignore this number. In the rare case where this number is higher, then this is your actual bandwidth.
  • Ping – the amount of time it takes for your computer to communicate with a server. On a VoIP phone call, this constitutes the latency (or delay) between you and person you’re speaking with. Small delays aren’t noticeable, so as long as this number is below 100ms, you should be good to go.

What is Bandwidth?

Bandwidth is maximum rate at which your network can transfer data. It’s one of the key factors in the VoIP speed test since it determines how many concurrent phone calls your connection can handle.

Bandwidth is measured by your download and upload speed – the rate information travels to and from your computer. Whichever number is lower is your bandwidth. Because most consumers download much more than they upload, most internet service providers (ISPs) design the network to allow faster downloads than uploads. This is why your upload speed is probably lower than your download speed.

Now, each VoIP phone call typically requires 100 Kpbs up and down – or 10th Mbps. So if your upload speed is 10 Mbps, you could theoretically handle up to 100 VoIP phone calls at once. The actual number, however, is closer to 10 or 20 calls. 

Here’s why:

There’s two main reasons why you need to give some leeway when measuring bandwidth. 

For one, internet speeds fluctuate throughout the day. When more subscribers in your local area are using the internet, speeds can vary up to 21 percent, according to studies on broadband internet connections.

Another factor is web browsing. If you’re using the same internet connection to check email, stream videos, or run web applications, your VoIP lines will have to compete for bandwidth. Heavy internet activity (Email + Youtube + Spotify) takes about 1 Mbps download per user. 

Fortunately they don’t require nearly as much upload bandwidth – the typically more important factor for VoIP phone calls. We’ll say you lose just about 0.25 Mbps per user for internet browsing. 

The exception is if you do a lot of upload-intensive work, like sharing videos/graphics or collaborating on files. Then this number could be a lot higher.

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