The history of ISDN in Australia

Telstra introduced its Integrated Services Digital Network (ISDN) to Australia in 1988. In doing this, Telstra became one of the first telecommunications carriers in the world to do so. At the time, ISDN was an innovative and capable technology. ISDN allowed high quality voice and data connections to happen over existing copper infrastructure. This improved the game significantly on dial-up internet, and paved the way for DSL internet services.

ISDN became the backbone of telephone communications in Australia. It then made way for VOIP-based communications as fibre networks increased the speed and reliability of data transfer, and SIP trunking eliminated the need for traditional analogue lines. As of the time of writing this article, more than 200,000 Australian businesses still make and receive calls via the Telstra ISDN network.

ISDN shutdown

Major telcos around the world have announced their intention to stop offering certain ISDN products, and that too with immediate effect. They have also announced a complete phasing-out of ISDNover the next decade. In Australia, the ISDN shutdown will commence in 2019. ISDN will cease to exist in the Australian public network by the year 2022. Products including ISDN2 Enhanced, ISDN10/20/30, DDS Fastway, Megalink and Frame Relay will be discontinued.

For businesses operating on copper ISDN services, the disconnection date will be at the end of September 2019. Customers that are using ISDN on Telstra fibre will move onto new products from 2022.

Impact of ISDN shutdown

The impact is plain and simple: Australian businesses will need to switch over to VOIP. Specifically, if a business still wants to make and receive calls directly from a 10-digit phone number, they will also require SIP Trunking to be set up.

What is SIP?

SIP, or Session Initiation Protocol (SIP) allows businesses to make calls over an IP connection between traditional telephone numbers. It is a virtual telephone line that will enable you to connect your phone system in the office and travel wherever you like while still being able to make and receive calls. SIP Trunks also provide users with scalability and quick provisioning, allowing them to increase or decrease the number of connections required for their business needs.

History of SIP

Session Initiation Protocol or SIP was designed in 1996 after VOIP started to increase in popularity. SIP trunking was developed to allow calls to be made between people using different voice technologies, for example, VOIP systems operated by different vendors.

Businesses use SIP to start IP based communication sessions between different network endpoints (examples of network endpoints would be VoIP call or video chat).

An advantage of SIP is that it can regulate quality; such as user location, accessibility, communication competences and setup & management of sessions. In addition to this, SIP also allows customisation so developers can receive other applications apart from phone calls.

SIP is crucial for initiating end communication sessions; however, the delivery of sessions is done through codecs. In line with this, organisations should view SIP as an application that is on top of communications.

Why SIP Trunking is key to a smooth transition from ISDN

An additional service, which is closely related to SIP, is SIP Trunking.

Without SIP trunking, we would not be able to dial from a 10-digit phone number and make a phone call to another 10-digit number. VOIP calls would be restricted to internal networks, and traditional analogue lines would be required to make calls outside of the office.

This form of communication allows VoIP phone systems and traditional landline PBXs to make connections. This method works through a VoIP phone system connecting to a SIP provider network through broadband.

What are the benefits of a SIP-based communication platform?

IP-based communication is gaining in popularity in Australia, and it is clear to see why. With the ability to establish connections between different devices (VoIP phone and mobile devices) SIP, which is IP-based can facilitate IP connections.

If SIP was not made available, communication between different devices would be challenging and require additional transcoding. In some instances, taking other steps to ensure the correct procedure for the transcoding may be necessary. Besides saving time with better communication tools, SIP also assists in establishing bandwidth by transcoding straight in the protocol.

Disadvantages of being late to the ISDN shutdown party

Every Australian business is advised to disconnect ISDN as soon as possible to avoid a bottleneck situation and to decrease the risk of downtime. If the migration to IP-based telephone does not take place before the final disconnection date, then your staff and clients face the risk of severe disruptions. Like any migration, it can be time-consuming, and with thousands of businesses needing to change over, don’t leave it too late to find an experience network integrator to help with the change.

Benefits of ISDN shut-down

Once ISDN communication lines are phased out, cloud communication services will be the default vehicle for businesses and individuals alike. The silver lining of the ISDN shut-down is the additional advantages that cloud-based communications can provide companies. A variety of cloud service options give cost savings and efficiency benefits, and the ability to scale quickly. Through the cloud, voice services are easier to manage remotely, and businesses can take advantage of new software, such as intelligent personal assistants and chatbots which integrate with voice services.

ISDN lines only allow for a limited range of communication options, primarily serving a traditional phone call. These barriers are pushed aside with the cloud having omnichannel contact centres where companies can speak to their customers beyond voice, including web chat and social media.

So – embracing the transformation from ISDN to VOIP and SIP will allow Aussie businesses to receive the benefits that cloud based communication and collaboration bring.


At CCNA, we are a very experienced network integrator. We are a carrier-independent and vendor-agnostic Voice and Telephony solutions provider. This means we are not tied to the likes of Telstra or Optus, and we work with the best technology available in the market. Our focus is our customer, their business, and delivering a reliable solution on-time, and ensuring it performs well ongoing.

Contact us to learn how we can help your business transition from ISDN to the cloud.