What's the Difference Between VoIP and IP Telephony?

Girl on video call on tablet
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Most people, including consumers and those in the media, use the terms voice over internet protocol (VoIP) and IP telephony (IPT) interchangeably, equating one to the other. VoIP, however, is really just a subset of IP Telephony. The difference between the two terms is so subtle, however, that they're widely understood to mean the same.

VoIP Is a Type of IP Telephony

This might sound confusing, but "telephony" refers to telephones, and internet protocol telephony deals with the digital side of telecommunications. It does so with the internet protocol known as voice over IP (VoIP).

What this means in the literal sense is that you're transferring voice signals using the internet. The protocol defines how voice travels over a network, similar to how the hypertext transfer protocol (HTTP) defines how data is to be understood, transmitted, formatted, and displayed by web servers and browsers.

To see it in a broader picture, think of IP telephony as the overall concept and VoIP as a means of transmitting voice to implement this concept. An IP telephony system can be, for example, an IP-PBX (private branch exchange), which has VoIP and its standards (SIP, H.323 etc.) along with many other things (e.g., CRM), geared toward better productivity.

What Does It All Mean?

IP telephony is a way of making a phone system digital to take advantage of the internet and any hardware or applications attached to it. The main aim of IP telephony is to increase productivity, so it's a term used most often in business environments.

On the other hand, VoIP is simply a digital transport vehicle for phone calls. In its different flavors, it works toward offering cheap or free calls and adding more features to voice communications.

Some describe IP telephony as the overall experience of communicating effectively and reliably using internet protocols. VoIP offers user-friendly features to facilitate the process.

The difference is quite subtle — so much so that using the two terms interchangeably can be acceptable in many contexts, even if just to avoid confusion.

Making Free Internet Calls?

There are lots of ways you can make free phone calls over the internet. The easiest way is to download an app for your tablet or phone that enables you to use it just like a regular phone without using up your calling minutes.

Viber, Skype, Facebook MessengerGoogle Voice, BlackBerry Messenger (BBM), and WhatsApp are just a few examples of ways you can call other people for free, all around the world. To make free calls from a Mac, check out some VoIP apps for free calling on a Mac.