VoIP Security

VoIP and Telecommunications

VoIP Terminology – Beginner’s Guide

A quick guide to VoIP vocabularySwitching to VoIP is not rocket science. Yet, when you research the topic for the first time, it sure feels like it. VoIP terminology is notoriously complex, and just to make it a little more confusing – every other word is an acronym.

Before yelling ‘It’s all Greek to me!’ and calling it quits, we recommend giving a go to this quick terminology guide. Here you’ll find a brief breakdown of must-have vocabulary that will come in handy, regardless of whether you are only considering implementing VoIP or already using it.

Most Important VoIP Terminology

Let’s start with the basics. If you are just getting started, here are key 9 terms that will help you understand the most important terminology of internet telephony.

1. Bandwidth

Bandwidth is the amount of data that can be handled and transmitted over a specific period of time. It is typically measured in kilobits per second (Kbps), and megabits per second (Mbps). You’ll need enough bandwidth to guarantee that your calls sound clear and uninterrupted. Skipping on this requirement may lead to unwanted jitters, echo or a complete breakdown of your phone call.

2. Codec

VoIP terminology would be incomplete without the word codec. It’s short for “coder-decoder” and refers to software algorithms that compress and decompress voice data. This way, it can be transmitted over the internet using less bandwidth while retaining its quality. There are various codecs in use today, but some of the most popular codecs include G.711, G.722, and G.729.

3. VoIP Hardphones

Hardphones are IP-compatible phones that are designed for use in business or professional environments and make calls with an internet connection unlike traditional landline telephones.

They are usually more durable and provide clearer audio quality than regular phone lines, making them ideal for use in offices and call centers. Additional features also typically include:

  • call queues
  • call forwarding
  • call holding
  • Wi-Fi connectivity
  • Bluetooth connection

4. IP Address

An IP address is essentially a unique identifier for a device that is connected to a network. When you make a call, the IP address guarantees that your voice data reaches the correct destination.

There are two main types of IP addresses: public and private.

  • A public IP address is assigned by an internet service provider and can be used to communicate with any other device on the internet.
  • A private IP address, on the other hand, can be assigned by providers to communicate internally with other devices on the same system.

5. Jitter

In internet telephony terminology, Jitter refers to the variation and delays in data packet transmission across an IP network typically as a result of the network congestion. In other words, it’s a measure of how well your connection can keep packets of data in order.

The internet is not a perfect environment for communication; sometimes packets get delayed or lost. Since conversation quality degrades when packets are out of order or have gaps between them, it’s important that they arrive timely and as intended to avoid choppy audio or even dropped calls.

6. Latency

VoIP terminology wouldn’t be complete without the term latency. While latency refers to the actual delay, jitter measures the fluctuation in latency. In other words, it describes the ‘lag’ between a caller speaking into their microphone and the actual time it takes for the other end to hear them.

Low latency is ideal for VoIP communications because it results in smooth and clear conversations. Keep in mind that average acceptable latency is anywhere between 150-300 milliseconds, and anything outside of this range may result in a significant drop of your call quality.

7. Router

A router is a device that forwards data packets between computer networks. VoIP routers allow calls to be routed from a caller to the receiver. They’re similar to regular routers but are often equipped with special features that make them compatible with different service providers.

8. Packet

The word “packet” is used to describe a small bundle or package. When we consider VoIP terminology, the work packet always refers to small units of a continuous stream of data that are broken down for transmission over the Internet.

9. Softphones

A softphone is a software application usually offered by your VoIP service providers that allow you to make and receive calls over the internet directly from your mobile phone, tablet, or computer.

Common Acronyms In VoIP

The key VoIP terminology may be enough for a beginner to touch the surface of the telecommunications world, but it won’t be enough without some important acronyms and abbreviations below:

1. ATA

An ATA, or an Analogue Telephone Adapter in full, is a device that allows you to use your regular analog phone for conversations that take place over the internet. You can skip investing in new equipment by repurposing your standard phone for your new communications setup.

2. DND

DND is generic Internet terminology that’s short for Do Not Disturb. This feature allows users to temporarily disable all incoming calls so that they can focus on their work or take a break without being interrupted. When DND is activated, callers will typically hear a busy signal or a message indicating that the user is unavailable. In some cases, they may also have the option to leave a voicemail.

DND can be activated manually by the user, or it can be set to automatically activate at certain times of the day (for example, during lunch). You can even whitelist certain numbers so that DND will never block them.

3. E911

E911 is part of specialized VoIP terminology that stands for Enhanced 911 and it is an important safety feature usually offered as part of the service package. E911 allows users to contact the nearest emergency response center by dialing 911.

This is similar to the traditional 911 service, but there are some important differences. With E911, your call will be routed through even if you are unable to speak or if the line is disconnected, and the E911 service will help identify your location to emergency responders and provide them with a call-back number.

4. H.323

H.323 is one of the most popular communication protocols, released in 1996 by the International Telecommunications Union (ITU). H.323 is a standards-based protocol designed to work with a variety of different services.

It defines a set of protocols that govern how audio and video communication devices can interact over IP networks, so it’s commonly used in conferencing applications like Skype and FaceTime.

5. PBX

PBX stands for Private Branch Exchange, and it is a business telephone system to manage a large number of incoming and outgoing calls. It can be done simultaneously thanks to a central control unit that routes these conversations.

VoIP PBX systems offer all of the same features as traditional PBX systems, but they use the internet to route calls instead. They may also include digital assistant, call queues, and other advanced call center features.


PSTN is telecommunications terminology for the Public Switched Telephone Network which is the traditional wired phone network. It uses copper wires to physically connect homes and businesses to a central telephone exchange. This exchange then routes PSTN calls to their destination using a complex system of switching equipment. PSTN is slowly being replaced by VoIP which transmits calls as digital data packets. This allows for more efficient use of resources and makes it easier to add new features.

7. SIP

SIP is the most commonly used protocol for VoIP, and it is a signaling protocol that is used to set up, maintain, and terminate sessions between two or more devices. A session can be something as simple as a phone call or a video conference. SIP is widely used because it is efficient, scalable, and can be easily extended to support new features and applications. It’s used with other protocols like H.323 to provide a comprehensive solution.

Final Words

Well, there you have it! A pocket dictionary of some common VoIP terminology to help you navigate this space without feeling lost. Of course, this is just a starter resource, for detailed information on more of these terms, you can check out this internet telephony guide and others on VoIP-Security.Net.org, but this post should do for a basic understanding of the most common terms and acronyms.

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