Before upgrading your phone system to a SIP trunk plan, you’ll need to understand what you’re buying – we’re here to help. Looking for more in-depth information? Try our FAQ page.

ATA - Analog Telephone Adaptor
An ATA or Analog Telephone Adaptor is a device that converts analog voice signals from a non-VoIP based telephone, to digital signals which can then be transmitted over the internet.

Also, ATA is one of the few acronyms we know of where 2/3 of the words are spelt differently based on where you’re from (Analog/Analogue and Adaptor/Adapter)!

CDR - Call Detail Record
A CDR or Call Detail Record documents all of the calls that have passed through a telecommunications providers infrastructure. Aatrox Communications providers a CDR at the end of each month to view details of all calls made, which comes in the form of a CSV file. Fortunately with Aatrox Communications you don’t have to wait until the end of the month with our Live VoIP Dashboards.
DID - Direct Inward Dialing

DID, or Direct Inward Dialling is where we (or your telco) assign a range of telephone numbers to your SIP Trunks. These numbers can then be called to reach users or endpoints on your PABX. Before DID, each phone required its own phone line – so an organisation with 30 staff would have 30 phone lines – even though they’d probably never all be in use at once. With DID, the same organisation may only need 10 SIP trunks, but based on the number called the call will be routed to and ring on the correct phone.

Bandwidth is the amount of data than a connection can transmit over a time period (usually a second). Bandwidth is measure both downstream (from the remote end to your end) and upstream (from your end to the remote end). Common bandwidth metrics vary from 56kbps on an old dial-up connection, up to tens or hundreds of megabits per second on an ethernet or fibre-optic connection.

Bandwidth is very important in achieving high-quality VoIP performance – have a look at our FAQ for more detail on your bandwidth requirements.

In VoIP terms, a codec converts analog voice into digital signals. Depending on the codec, compression may be used to decrease the bandwidth requirements. Aatrox Communications’ SIP Trunks support a number of different codecs – and you are able to choose which one(s) to use on your PABX or device. See or FAQ for a list of supported codecs.
IP - Internet Protocol
IP or Internet Protocol allows computers to talk to each other – and in this context, phones, network equipment, many printers, and so on all have computers inside them to allow them to be part of this conversation. VoIP, or Voice over IP is where devices send voice signals over the IP network – and SIP Trunks are a key piece of VoIP.
ISDN - Integrated Services Digital Network
ISDN is a standard for data and voice communication from way back in 1988. Put simply, it’s how many business phone systems have been connected to the telephone network for many years. ISDN lines are typically bought in blocks, such as an ISDN2, ISDN10 and ISDN30 (for 2, 10 and 30 lines respectively). There are a number of limitations of ISDN (after all, it’s a very old technology), which have been addressed by VoIP technology. Most telecommunication providers around the world have announced shutoff dates for their ISDN networks (some not for many years) – but it’s well and truly on the way out.
IVR - Interactive Voice Response
An IVR uses touch-tone responses or increasingly voice commands to allow users to interact with a phone system. Think “Press 2 for sales” or “Enter your account number”. Standard functionality called an “auto-attendant” and allows callers to be router to the correct place – and helps organisations look more professional.
Jitter in VoIP (or more broadly in IP communications) in the variation in the delay, or latency, of received data packets. Jitter is bad – and can result in some packets being delayed substantially, and even taking longer to arrive than packets sent after it. Jitter can happen for a number of reasons – generally problems on a network level – and can have major consequences for VoIP performance.
Latency is how long a piece of data, or packet, takes to get from point A to point B. Sometimes latency is measures as a round-trip – i.e. from point A to B and then back to A. High-latency connections mean that VoIP packets take a long time to get from the person speaking to the person listening – which is not good, and can result in a noticeable delay. We’ve all experienced phone calls where people keep speaking over each other because of a delay, and it makes communication much less fluid.

Generally speaking, the further a signal has to go, the longer the latency (there can be other delays such as poor configuration, but we’ll ignore those for now). An extreme example is satellite internet connections, which route your internet connection through a satellite in a geostationary orbit 35,000km above the earth. That means by the time your voice has reached whoever you’re talking to it has probably come 70,000km. Even at the speed of light, that takes about 1/4 of a second, which they experience as a moderate delay. Wow!

LNP - Local Number Portability
LNP or Local Number Portability allows you to move your telephone number(s) between providers of your choice. It’s a law that all telecommunication providers in Australia need to follow – specifically the Telecommunications Act 1997, and further regulations from ACMA (the Australian Communications and Media Authority) and the ACCC (Australian Competition and Consumer Commission).

LNP sits alongside mobile number potability and local rate and freephone number portability (1800, 1300 and 13 numbers).

Know your rights! Not all providers will willingly allow you to port numbers away from them – but unless you were advised otherwise when you signed up for their service, they are not allowed to deny your request.

A PBX is a Private Branch Exchange, and a PABX is a Private Automatic Branch Exchange. To understand what a PBX is, we’ve got to look back – way back. Before computers, a phone call involved speaking to an operator who would manually plug in wires to link up your phone with whoever you were calling. Once the circuit was completed, you had a phone call. These operators worked in rooms called PBXs, and they existed in cities, large companies, suburbs, and so on. Once computers – or more specifically electronic switching – entered the picture, these PBXs were able to be automated, and these new automated systems became known as PABXs. Over the years plenty of additional technology has been introduced such as conference calls, intelligent routing, and so on.

These days, a manual PBX is something we might see in a museum – so there’s no real distinction between PBX and PABX and the terms are used fairly interchangeably.

PSTN - Public Switch Telephone Network
The PSTN or Public Switched Telephone Network is the global network of telephones, using a mixture of older analog technologies and newer mobile and IP-based technologies. A voice network can exist that is not connected to the PSTN – think something like an intercom or walkie-talkies – but in most cases a voice network will need to be connected to the PSTN in some way. This is what SIP Trunks do – connect a phone system to the public telephone network, over the internet.