What is VoIP?
Simply put, VoIP is a way of using the same communications protocol to carry voice traffic as the internet does for data traffic.
When you use a browser to access a website, the data is transferred between the website and your browser using Internet Protocol or IP. In IP, the data is broken up into discrete parts called packets.
These data packets move across the internet with each packet taking its own route from the website to your browser. Once the packets get to your computer, the browser reassembles them into a web page.
It’s as if you and ten of your friends left from work and got into ten different cars to meet up for dinner. Each car might take a slightly different route to get from your office to the restaurant, but once each car got there, your group would reassemble before entering the building.
For decades now, when you placed a telephone call, your voice was carried over the Public Switched Telephone Network (PSTN). The PSTN is fundamentally different from IP because it is circuit switched. When you place a call, a dedicated circuit is established between your phone and the phone of the person you are calling. Your voice signal travels across that dedicated circuit continuously until you end the call.
Using the PSTN to make a call is like you and your friends traveling in your cars and driving bumper to bumper along exactly the same route to dinner. Further, once you start on that route, it is closed to all other traffic and dedicated to your group of cars.
Phone companies who own and operate the PSTN typically charge you tolls for using the route, usually for every minute that you spend on the toll road. VoIP is a way of bypassing the toll by avoiding the PSTN. When you place a call on a VoIP network, your voice is digitized and broken up into “voice packets” that move across the network in a way that’s similar to data packets.
If you walked into the server room of most businesses today you would find a data connection (T-1 line, DSL or cable broadband) to carry the “data packets” and a connection to the PSTN to carry voice traffic. If the company was using VoIP, you’d find just one connection because, for VoIP, “voice packets” and “data packets” use the same network.
Internet Phone Calls?
It’s often said that VoIP is using the internet to make phone calls. That’s not really true especially for VoIP systems that are used for business calls.
The public internet is a chaotic place. Your data packets are moving across the internet along with those of tens of millions of other people. More often than you realize, one of your packets gets lost and never makes it to its final destination. For most routine data traffic like web pages, this is not a huge problem. However, for applications like video or voice, it is big issue.
If voice packets get lost or don’t arrive on time, the call quality will suffer and your conversation will sound like a bad cell phone call. For that reason, business class VoIP calls are carried over a private, managed network that ensures Quality of Service (QoS) for both voice traffic and data traffic. These private networks connect to the public internet and to the PSTN to ensure that voice and data traffic can reach users who are not part of the private network.