The next few years could create interesting challenges as well as opportunities for Australian businesses who want to communicate better with their customers and staff.



Since the early 1990s, the country’s standard for hosted phone systems has been powered by called Integrated Services Digital Network or ISDN.

This digital tool was an improvement from earlier service called PSTN, or Public Switched Telephone Network. PSTN is an analogue system, which means it powered by an actual copper wire network, what we think of as landline service.

Although PSTN may sound archaic to digital enthusiasts and may not have all the features that ISDN offered, it still is a basic access telecommunication service that was nice to have for some, especially small business, that may not have needed too many capabilities or features beyond a handful of fixed telephone lines.

PSTN service also included a tool called a “line hunt,” where phone lines could be grouped together. This way, if a caller called a main number and it was busy, the phone system would start automatically looking for the next available number, such as Lines 1, 2, 3, etc.

But it does have its limitations, including incompatibilities working with wireless systems.

ISDN became useful in that it could provide at least two simultaneous connections over one line, rather than one connection and one phone number for each line with PSTN. This made it easier for businesses to send data, video, or a fax while speaking on the phone or performing other tasks, something that would be mechanically difficult with PSTN service.

ISDN became nice to have for larger companies that had greater demand for multiple lines and multiple telecommunications tasks. It was cost-effective as well but is based on phone needs, not cloud-based storage and activity needs that the modern company prefers.


ISDN Disconnection

As useful as ISDN has been for the last few decades, Australia is moving to something new beyond PSTN vs ISDN.

At the beginning of 2019, the disconnection of Australia’s ISDN lines began. Telestra, the country’s largest phone service provider, is no longer selling ISDN products and services to its business or residential customers. It began the disconnection process for ISDN companies in September 2019, and the entire network is expected to be fully decommissioned by 2022.

The ultimate goal is to get customers ready for the NBN (National Broadband Network), which delivers higher speed services and other improved features for residential and business customers. But before this happens and to avoid complete disconnection, companies are also encouraged to sign up for another option called SIP, or Session Initiation Protocol.

A SIP trunk/ line is IP-based, meaning they can operate on existing data networks using data cloud options. They can be scalable and offer as many lines as needed.


From PSTN to SIP

Technology has advanced exponentially in the last 20 years, leading us to today: 2020. With multiple high-speed internet connections available, integrations of phones, computers and other devices, for the most part – SIP trunk services and unified communications have taken over.

Both businesses and individuals have embraced the benefits of IP telephony – from families keeping in contact from different countries, to businesses communicating with their remote offices via PBX as if they were in the same building.

Many companies (and residential areas) are deciding to make the switch and replace all traditional PSTN phone lines with SIP based phone systems and this trend doesn’t appear to be ending any time soon. In the USA, over a quarter of households surveyed no longer even used landlines and ISPs are taking advantage of this fact, with many of them offering voice and data services bundled with their internet services.

If you’re looking to learn more about SIP and other VoIP technologies, check out our additional resources below. Alternatively, feel free to get in touch with one of our SIP trunking specialists for a closer look at your business and how we can help.

Further Reading

Aatrox Communications is an Australian owned and operated full service SIP trunk provider. We specialise in connecting the traditional telephony network to the internet for small and large businesses.