VoIP Bandwidth: How Much Do You Need?

How to make phone calls over the internet

Stock photo of a Cisco Systems IP desk phone sitting in front of two other phones on a desk.

Roman Olshevskyi/Pixabay

Using a VoIP phone service can be a cost-effective way to make phone calls, as you don't need a landline and can make calls via the internet. But to make calls over the internet you'll need to consider the very important relationship between Voice over Internet Protocol (VoIP) and bandwidth, and know how much bandwidth you'll need to support those calls.

Let's go over the basics of internet bandwidth, how it relates to VoIP phones, and the minimum bandwidth requirements you'll need to meet to successfully place VoIP calls.

What Is Internet Bandwidth?

Before we get into how bandwidth and VoIP phones relate to each other, it's important to understand what bandwidth actually is, what it isn't, and what its limitations are.

Basics of Internet Bandwidth

Essentially, bandwidth, as it relates to internet connections, is the capacity of an internet connection to move a given amount of information/data per unit of time (usually seconds). When it comes to internet connections, this capacity is often expressed as "megabits per second" or Mbps or Mb/s. Bandwidth is essentially the data transfer rate an internet connection has the ability to support. For example, an internet connection with a bandwidth of 15 Mbps means that internet connection has the capacity to move 15 million bits of data per second.

Generally, internet connections with higher bandwidths are able to transfer given amounts of data faster than connections with lower bandwidths.

It's important to know the amount of bandwidth your own internet connection is able to support before you set up VoIP calling, because VoIP calling relies on internet connections to place phone calls. To determine your internet connection's bandwidth, use an internet speed test site.

Bandwidth Misconceptions

One of the biggest misconceptions about internet bandwidth is the idea that whatever the stated amount of bandwidth your internet connection is expected to have is also the exact data transfer rate you can expect when actually using your internet connection. In most cases, your internet connection will not perform data transfers at the bandwidth level stated by your ISP. Which means, just because you were told your connection should be able to transfer data at a rate of 60 Mbps doesn't mean it actually will during your everyday usage of it.

This is because connections like Wi-Fi and Ethernet have to manage other network features like packet headers and control messages; features that also consume bandwidth in addition to the files and data you were trying to transfer (like a VoIP phone call or a movie). All of this additional bandwidth consumption can significantly reduce the amount of actual bandwidth available to you, which can lead to your bandwidth and connection speeds reduced by up to 50% of what it was supposed to be.

On a related note, another misconception about bandwidth is the stated level of bandwidth is the total available amount of bandwidth for each download request or person using a given internet connection. This is not the case. In fact, even if your network didn't have to manage other bandwidth-hungry network features, the stated level of bandwidth for your internet connection would still be divided among the different people or download requests that need to consume bandwidth to do things like download files or make VoIP calls.

Basically, the stated level of bandwidth is the total amount of possible bandwidth for a given household's internet connection. Which means your internet connection's bandwidth (the set data transfer rate that you paid for) will be divided among the people and download requests using your internet connection.

Each person or download request will only get a portion of the total amount of possible bandwidth you've paid for. Which means the more people or download requests there are using your connection, the slower your overall connection will be. So, when determining your bandwidth and how much of it you'll need for things like VoIP, you'll want to test your internet speed properly. Because a higher bandwidth won't necessarily be enough if your bandwidth consumption still exceeds it.

Limitations of Bandwidth

There are a number of limitations with bandwidth; the biggest being bandwidth throttling. This is when your internet connection's bandwidth is deliberately slowed down, usually by your internet service provider (ISP). There are several reasons an ISP would engage in bandwidth throttling, including reducing network congestion, to encourage customers to upgrade to a more expensive level of service just to avoid getting throttled, or to throttle bandwidth being used for a certain kind of online activity or website. Sometimes, throttling is used to enforce bandwidth caps (a bandwidth usage limit) built-in to paid internet service plans.

Other, lesser-known limitations associated with bandwidth include too many browser add-ons and extensions that consume bandwidth, and excess bandwidth consumption due to malware infections. These limitations can cause your internet speed to slow down because they consume too much bandwidth.

VoIP Phones and Bandwidth

VoIP calling tends to be a heavy consumer of bandwidth because it requires more bandwidth to transfer voice data than, say, simple text. And so, because it takes more bandwidth to move the voice data involved with VoIP phone calls, the relationship between VoIP and bandwidth is such that if you want decent or high quality voice calls, you'll need to invest in an internet connection that can support faster connection speeds and higher bandwidth.

Currently, the consensus is that when it comes to setting up VoIP calling, the best kind of internet connection to use is a broadband connection, as it's considered to be the only kind of internet connection that can supply the minimum bandwidth required to support good quality VoIP phone calls.

VoIP Phone Bandwidth Requirements

In addition to using a broadband internet connection to facilitate your VoIP calls, it's also recommended your bandwidth be at least around 512 kbps (kilobits per second), which works out to 0.512 Mbps. A basic broadband connection should be able to provide that much bandwidth, since many broadband providers offer a minimum of 512 kbps with their service.