Voice over IP (VoIP)

VoIP technology supports the communication of voice calls over IP networks, most commonly the Internet. Rather than use traditional telephone cables it makes use of various types of modern Internet infrastructure.

PSTN (Public Switched Telephone Network) is the term used to describe the traditional technology that mankind has been using to make phone calls for centuries. This involves mechanical phones that send analogue signals via copper cable and transmit sound using vibration, which is transferred and amplified at telephones exchanges. VoIP technology, by comparison, is largely software based and transmits sound as audio data sent over the Internet via the vast web of network cables and satellites that now cover the Earth

With VoIP technology, the recorded audio is split into individual ‘packets’ of data and sent as a digital signal, almost like a pulse. At the receivers end the packets are put back together and played in sequence to recreate the audio. In reality, this process is so fast and fluid a listener wouldn’t even notice the gaps. Video calls can be sent in the same way, but require a much faster Internet connection.

PSTN technology is old and outdated and with the ever-increasing interest in VoIP, huge reductions in cost and improved technology, Voice over IP is looking to soon replace the traditional PSTN system entirely.

There are three different variations of VoIP which we will look at in more detail here:

How Voice over IP (VoIP) Works

ATA stands for Analogue Telephone Adaptor and is a traditional VoIP method that is becoming less common these days. It consists of a standard telephone which is connected to a computer via a small piece of equipment called an ATA box. The ATA box converts the signal from analogue to digital and uses the PC’s Internet connection to transmit the call. You simply plug the telephone into the box, as you would into the wall socket, and then plug the box into the PC. Often a service provider will offer additional software with advanced features that you can use to customize your setup.

An IP Phone

An IP Phone is like a normal telephone but with the addition of an Ethernet (RJ45) plug instead of the usual RJ11 plugs found on a normal phone. Using an RJ45 plug, an IP phone can be connected directly to the Internet as you would a PC. IP Phones have network cards built into them and can be configured with IP addresses in the same way computers are. Many new IP phones come with wifi capabilities and can connect to any wireless network in the same way as a laptop or mobile phone.


Computer-to-computer connections don’t require any additional hardware. In this scenario, one would simply use the microphone and speaker on their PC or laptop and make phone calls that way. In fact, these days any networked device can make and receive VoIP calls in this way via a number of different apps. The most commonly-used is the popular video calling software Skype.