SIP • Last Updated 9/29/2023

6 Steps to Follow when Switching from ISDN to SIP

For businesses that have not moved off the ISDN, the transition to SIP is a big one. But when managed well, it can be seamless.

Fiona_McDonnell

By Fiona McDonnell

Six Steps to Switch from the ISDN to SIP Trunking

In 2016, Australian telecoms giant, Telstra, announced that they would be discontinuing the ISDN product line, and that a complete switch off of the infrastructure was imminent. This meant that companies which depended on the ISDN for their communications would to switch from the ISDN to SIP or other cloud-based communication platforms.

The driving force behind the switch off is the rollout of the national broadband network (nbn™) across Australia. The nbn™ will give the majority of Australians access to high-bandwidth internet which will be capable of supporting SIP connections. This capability will almost completely diminish the need for ISDN, as internet-based communications become more reliable. The date for the complete switch off of the network currently stands sometime in 2022, allowing companies more time to adequately plan and budget for a shift to an internet based communication system.

What's the Difference Between ISDN and SIP?

There are a couple of main differences between the ISDN and SIP. First off, the ISDN delivers voice services over the traditional copper telephone network while SIP Trunking is an applucation layer technology. As a result, ISDN connection requires an on-premise connection, while SIP connections allow workers to connection from anywhere with internet access.

Switching from ISDN to SIP

Although there are many upsides to switching from ISDN to SIP Trunking, it is still a big move for businesses and can seem daunting. With that said, we have created an easy-to-follow guide to show you how to manage a seamless migration from ISDN to SIP. Follow these guidelines and you should have your SIP Trunk up and running in no time!

1. Carry out a hardware audit

When switching to SIP, you first have to ensure that the phone system you are currently using is compatible with IP technology. You can check this by a simple google search of your existing phone series.

2. Check your network bandwidth

SIP requires various bandwidths depending on the number of connections on your network. However, with the rollout of the nbn™, this shouldn't be a concern as access to high speed internet becomes ubiquitous.

3. Investigate potential providers

It’s important to engage with a number of providers before choosing the right one. You’ll also need to look at reviews to ensure they deliver a quality service. G2 is a great place to start as it tells you a lot about different companies and guides you on what you should look for in a provider.

4. Trial potential partners

When you have your shortlist, try out some potential partners. Start by configuring some trunks with each provider and test their support teams. It's important to remember that these will be the people that will be helping you when you have issues which could potentially affect your business, so it's paramount that they’re competent and you trust them.

To this point, you should ensure that your provider is an industry expert and has a support team that is on hand, 24/7/365.

5. Arrange number porting

When you’ve picked a provider, you'll need to arrange number porting. This has the potential to be a cumbersome experience so it's best to partner with a provider that has automated porting as standard.

6. Run the new with the old

Finally, once you have chosen a SIP provider, it’s best to run your new system in parallel with your ISDN system for a number of weeks for a couple of reasons:

  • Firstly, when moving systems there is always the potential for a few hiccups, and running both concurrently will allow you to focus on ironing out the kinks in the new system without compromising your communications while you do so.
  • Secondly, it allows your employees to adjust to your new platform. While most SIP software is intuitive and easy to use, it is still a change and some people take more time to adjust to others.

The Benefits of SIP

While this can seem like a lot of work upfront, the benefits of SIP will have an immediate impact on productivity and your bottom line. Moving to a cloud-based telephony solution offers more flexibility and greater cost savings for the majority of businesses. Let’s take a closer look at some of the major benefits:

SIP allows businesses to scale efficiently

A business using ISDN can only add lines in blocks of 5 and this requires a physical installation. With SIP, you can add as many lines as you want, in real time. While this has obvious implications from a time-management perspective, it also has consequences when considering the cost of the service.

SIP Connections can be removed easily

If your business is seeing a decrease in call volume or size, you can switch off the lines and save money immediately. ISDN lines are more difficult to remove and therefore many businesses end up paying for lines they do not need.

SIP Connections are not tied to a physical location

Meaning your staff no longer have to be present in one workspace. This mobility has proven to be an extremely valuable feature of SIP technology during COVID-19, as city and country-wide lockdowns are announced quickly, requiring employees to work remotely.

Servicing of SIP Connections is delivered remotely

Management of SIP services differ greatly from the management of the ISDN network. Traditionally, ISDN needs to be managed locally as sometimes fixes to the hardware are required. With SIP solutions, management services can be delivered remotely and 24/7/365 support is a reality.


For businesses that have not yet made the switch off the ISDN, there is no time like the present. The transition to a SIP trunking product is a big one, but as we have shown it can be a seamless one and is guaranteed to add value to your business.




With Telnyx, it's easy to port numbers and start making calls with our SIP Trunking product. Sign up for an account today, or chat to our experts to see how Telnyx can help your business grow.

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