Jargon Busting: VoIP

By - Lewis
05.02.20 09:25 PM
If you do look to update your communications system, you’ll be faced with a mountain of jargon. Telecoms is a technical field, and as such it has its own lexicon. You might even have spotted a few technical terms in this guide already. To make sure you know where you stand, let’s define and explain as many as we can.

The following glossary covers the most common words, acronyms, and phrases you may come across. It is related both to VoIP and to the traditional alternatives which it can replace. As ever, if you have any questions please reach out.

The capacity of a network to transmit data from one point to another in a given time period. It is often measured in 1000 bits per second (kbps). The higher the amount of available bandwidth, the more VoIP calls a network can support. If your internet connection has very limited bandwidth, the quality of a call will be lower. 


Codecs can be either hardware devices or software-based processes. They’re used to compress, encode and decompress data. In the case of VoIP, codecs convert audio voice signals into digital data packets. They then compress the data for transmission and re-convert it at the ‘other end’ of a call.


DSL stands for ‘Digital Subscriber Line’. It refers to the traditional phone technology that lets a broadband connection be carried over existing phone lines. All the while still allowing analogue phone signals to travel along the same copper lines.

IVR or Interactive Voice Response is a feature of traditional telephony. It’s the interactive service that lets callers use menus and handles call transfers. Think ‘press one for the accounts department’ etc.

The time taken for the transmission of data. The higher the latency, the greater the delay between the start of a transmission and data being received at the other end. High latency can be an issue for VoIP. Voice delay is noticeable with a latency above around 150 milliseconds. Considerably more than that and a conversation will be difficult.


PBX stands for Private Branch Exchange. It’s the name given to a private telephone network used within a business or organisation. It’s your PBX which lets you press a button on a desk phone to reach someone else in your office. 

The Real Time Transport Protocol. An internet protocol that often transmits the data packets related to VoIP calls. It also carries audio or video streams for other forms of multimedia communication. Secure Real Time Transport Protocol – The encrypted (and so, secure) variant of the RTP.

SIP Trunking
A way of delivering voice communication over the internet. It’s in many ways an alternative to VoIP. It typically involves connecting a PBX to the internet. This gives added control to a user but does require a fair bit more equipment to get up and running than a VoIP phone system.

The name given to software or apps used to make VoIP calls. In the case that you use your computer or tablet and not a VoIP phone. Most ‘softphones’ have an interface that looks like a phone handset when it appears on your screen. It will have a keypad, display and be workable via touchscreen or computer keyboard.

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