Overall call quality and the number of phone lines supported by a VoIP phone service largely depend on the bandwidth of your internet connection. Use our free VoIP speed test to measure your bandwidth, and keep reading to learn about VoIP bandwidth requirements, including what to do if you get a poor bandwidth test result.
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How Many Phones Can My Internet Connection Support?
The faster your internet connection, the more VoIP phone lines it can support. For example, a 500 Kbps upload speed will support a maximum of five lines, whereas a 10 Mbps upload speed will support a maximum of 100. Your speed test should tell you how fast your internet is, and therefore, how many phones it can support. Read our article on business phone systems for more information.
For example, the results of your speed test will give you two numbers: your download speed and your upload speed. Because you’re limited by the lower of the two numbers (which is almost always your upload speed), we’ll refer to that as your bandwidth. Make a note of this lower number from your test. Next, find the closest match to your bandwidth in the chart below:
Number of Lines Based on Your Bandwidth
|Bandwidth (Upload Speed)|
Maximum vs. Recommended Number of Lines: Knowing the Difference
The number of phone lines your VoIP system can support doesn’t only depend on your internet speed. It also depends on how much of your bandwidth is available for VoIP use versus other uses like internet browsing, streaming, email, online software, and web-based point-of-sale (POS) systems.
The maximum number of lines assumes all of your bandwidth is being used for calls, while the recommended number of lines takes into account other browsing activities as well as expected fluctuations in your internet speed throughout the day. Cable internet speeds tend to fluctuate, whereas fiber optic connections are more stable.
When selecting an internet provider for your VoIP service, you may be limited to what’s available in your particular building. If not, check with your neighbors and for recommendations and reviews on the best service in your area. You can learn more about the different types of internet connections and get tips on choosing a service package in our guide on how to set up internet for your business.
How to Do a Manual VoIP Speed Test
While the test above is accurate, some might need to figure out how many phones their internet supports manually. You can do some simple math to calculate exactly how many VoIP phones lines your internet connection can support:
- Multiply your upload speed by 1,000 – This converts the units from Mbps to Kbps. If your speed is already expressed in Kbps, then skip this step.
- Divide your result from step 1 by 445 – This will tell you the recommended number of phone lines your connection can support.
- Divide your result from step 1 by 100 – This is how many phone lines your VoIP system can support in a perfect world, assuming your internet connection is stable and consistent and no bandwidth is being used for other activities, like browsing or downloading.
For example, here are the results of my own speed test:
My results show an upload speed of 11 Mbps. Therefore, the recommended number of VoIP phone lines that my internet connection can support is 24 and the maximum is 110.
What the VoIP Speed Test Numbers Mean
For a deeper understanding of your bandwidth test results, let’s take a look at what the VoIP speed test numbers mean. We’ll also define some common terminology that often comes up when you test your internet speed to help you interpret the results.
Your connection’s upload speed, measured in megabits per second (Mbps), is typically lower than your download speed because it reflects the actual bandwidth available to your computer.
The maximum amount of data your connection can receive is measured in Mbps. In the rare case where this number is lower than your upload speed, then this is your actual bandwidth.
Ping refers to 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 the person you’re speaking with. Small delays aren’t noticeable, and a ping speed below 100 ms is generally acceptable.
Jitter is a measure of how well packets of data travel across your internet connection and arrive in the correct order. Jitter reveals potential call quality issues if results are higher than 30 ms.
VoIP Bandwidth Requirements
Bandwidth is the maximum rate at which your network can transfer data. Because VoIP technology transmits your voice as data, it’s one of the key factors in determining how many concurrent phone calls your internet connection can handle. Bandwidth is measured by your download and upload speed (the rate that information travels to and from your computer). Whichever of the two numbers is lower is your bandwidth.
Because most users download much more than they upload, most internet service providers (ISPs) design their networks to allow for faster downloads than uploads. This is why your upload speed is most likely lower than your download speed.
Each VoIP phone call typically requires 100 Kbps up and down, or 1/10th of an Mbps. So if your upload speed is 10 Mbps, then your network can theoretically manage up to 100 VoIP phone calls at once. The actual number, however, is closer to 10 or 20 calls. This is because other programs on your network are taking up bandwidth at the same time.
Bandwidth Limitations for VoIP
|Bandwidth (Upload Speed)|
There are two main reasons why you need to give some leeway when measuring bandwidth. First, internet speeds fluctuate throughout the day. When there are more users in your local area using the internet, speeds can vary up to 21%, according to one study of broadband internet connections.
Another factor that affects bandwidth is web browsing. If you’re using the same internet connection to check email, stream videos, or run web applications, then your VoIP lines will have to compete for bandwidth. Heavy internet activity, such as the concurrent use of email, YouTube, and Spotify, takes away about 1 Mbps download speed per user.
Fortunately, managing email while simultaneously streaming music doesn’t require nearly as much upload bandwidth, which is typically the more important factor for VoIP phone calls. The exception, of course, is if you do a lot of upload-intensive work, such as sharing videos and graphics or collaborating on files. If so, then this number could be a lot higher for you.
What to Do if You Get a Poor Bandwidth Test Result
Most broadband connections will give you more than enough bandwidth for VoIP calls to run a small business. With an average upload speed of over 6 Mbps in the U.S., a typical connection can manage 12 or more lines without much challenge.
On the other hand, if you need more than 12 lines, or if your connection speed is lower than 500 Kbps, then your VoIP call quality may suffer. If you test your internet speed and get a poor result, you can usually improve a bad connection by allocating more bandwidth.
Bandwidth allocation means specifying which internet activities get priority on your network. In other words, you can allocate a certain percentage of your bandwidth to your VoIP service. Then when your network gets strained, it will prioritize your VoIP traffic by slowing other activities like internet browsing and download/uploading files before it slows your calls.
To set up bandwidth allocation, you’ll need to adjust the Quality of Service (QoS) settings on your router. You can usually do this online by going to the website of your router provider (e.g., Netgear, Linksys, D-Link, and Cisco) and logging into your control panel, or searching for “[Your Router] bandwidth allocation” on Google for instructions.
How Your Choice of VoIP Provider Affects Call Quality
VoIP providers differ in how they handle your calls, such as how they encode your signal from voice to data. One of the biggest factors that can affect call quality, however, is how many data centers the provider operates. Smaller VoIP providers that have just one data center, for example, may be prone to more issues when their network is strained. By contrast, larger companies can offer more reliable service by spreading their service out across locations.
We recommend RingCentral as the best full-featured VoIP provider for small businesses. It’s one of the most powerful VoIP systems right out of the box, with a built-in conferencing system, support for up to 200 callers, and unlimited video and audio conferencing with live U.S.-based phone support 24/7. Click here for a free 15-day trial.
Useful VoIP Resources
Check out the following articles for more detailed information on VoIP systems:
- VoIP vs Landline – What’s the Best Small Business Phone System: Find out about the advantages and disadvantages of VoIP for your business with our comparison guide.
- Things to Consider When Setting Up VoIP Phone Service: Learn more about VoIP and everything you should consider when looking for the best VoIP phone service provider for your needs.
- Choosing the Best Business Internet Service Provider: Take a look at our comparison guide on the best business internet provider in each region of the U.S. based on price, speed, reliability, customer service, and contract terms.
- Small Business VoIP Service: Who Is the Best: Check out our comparison reviews of our favorite VoIP service providers, with information on pricing and features.
- VoIP Service User Reviews: Read reviews from existing users and get the full story on how they feel about their VoIP service providers.
The Bottom Line
Most broadband connections are well over the requirements to support one to 10 concurrent VoIP phone calls. With a high-speed business connection, that number may be even higher. Our free internet speed test tool will help you confirm you have the bandwidth requirements to support the number of phone lines you need in your office.
Remember to check out RingCentral if you’re not satisfied with your current VoIP provider. You can have your whole office up and running in just a day. RingCentral features unlimited calling and conferencing, toll-free numbers, and customizable caller ID. Click here to try RingCentral free for 15 days.