ISDN Switch-Off: The Future Is Coming

In 2015, BT announced they would be preparing for a complete ISDN switch-off in 2025, starting with a gradual phase-out of the older systems starting in 2020. At the time, and even now, not many people or businesses were phased. “We’ve got years yet!” were the arguments from businesses up and down the country. And yet, less than 6 months away from the first ISDN/PSTN phase out in 2020, and businesses are still just a blasé about it now as they were back then. But change is coming. And its coming fast. So what should you do? Luckily, Pure Cloud have you covered. But the key is in preparation.

What is ISDN & PSTN Anyway?

PSTN stands for Public Switched Telephone Network. This was the first-generation landline telephone system originally set up for voice communication. It soon became the most reliable method of making voice calls and the main carrier for internet activity across the world.

ISDN, which means Integrated Services Digital Network was born not long after. This was ground-breaking at the time.  Instead of separate lines for voice and data, ISDN allowed for the digital transmission of voice, video and other services simultaneously, using the traditional PSTN network. Pretty clever.

So why the ISDN Switch-Off?

Well, like most reasons we upgrade anything, because it’s old. In the same way we replace cars, phones and TV’s when new models come out, that’s what the ISDN Switch-off is all about.

Despite having been updated radically over the decades since ISDN lines were introduced, these lines are still essentially the same in setup and design as the original phone lines of the 1800s. And as new technologies emerge, the associated maintenance and running costs of sticking with ISDN just isn’t worth it.

Technology has changed the way we work. Everything else has moved on, now it is time for telecoms to catch up.

What Does the ISDN Switch-Off Mean for Me?

Realistically, in the short term, not a lot. If you are one of the 2 million BT ISDN clients that is currently on these old systems, then you have about 5 years to review your options. Once you’ve settled on a way forward, changing is relatively easy (this is another advantage of moving away from an ISDN network!).

But it is wise to start thinking of alternatives now. There are options already available that are delivered in a slightly more modern way, that mean you can take advantage of more up to date collaboration tools. Essentially, the sooner you start considering your options, the easier the transition will be for your business to start taking advantage of the opportunities that other voice solutions can bring. Don’t worry, we can help you with that too!

While 2025 may seem a long way off, 2020 is just around the corner. If your current traditional telephone contract is up for renewal within the next couple of years, now is the time to start exploring the benefits of IP and SIP technologies.

Alternatives to ISDN

Ahead of the ISDN Switch-Off, you have two choices when it comes to your telecommunications: SIP and VoIP. Session Initiation Protocol (SIP) is a protocol used in Voice over Internet Protocol (VoIP), and allows users to make voice and video calls on a global scale using computer and mobile devices with an internet connection.

The biggest and most noticeable difference for businesses is you will no longer be tied down to a fixed line at a fixed location. This is often referred to as a cloud-based telephony system. Instead of having an old connection that carries both voice and data, you’ll have one, fast data connection, which also carries your voice calling

Things To Bear In Mind

One thing you need to work out first is if you have enough bandwidth to deliver voice traffic over your internet connection (on top of everything else your office does). If you don’t have enough bandwidth you could experience poor audio quality or intermittent service which is not ideal. Typically, an FTTC or Dedicated Leased Line are both good products for VoIP Services to run over however, there are circumstances where you can run VoIP over a standard ADSL Connection.

Most modern office phone systems already support VoIP, but if yours doesn’t, you can easily replace your existing phone system.  The saving you will make against your existing telephone bills is normally more than enough to cover any technology upgrade you need to make, but if you are not sure what system you have or whether it supports IP technology, get in touch!

Businesses will be unable to buy new phone systems that use ISDN and PSTN after 2020. If you’re thinking about upgrading your current system to support these technologies is probably going to be a waste of money – think about VoIP instead.

Benefits of Switching to VoIP

Aside from being a more modern, progressive technology, VoIP has many advantages for businesses over PSTN and ISDN:

You can reduce your line rental costs

VoIP — unlike traditional solutions — does not run over copper lines, meaning it is line rental redundant. The only thing you need is an active internet connection. On average you could save up to 50% on your line rental and 25% on calls.

It is incredibly scalable and flexible

You’re in control. Add lines, take them away, split calls – it’s up to you. Plus, Choose how and where you want calls delivered and make changes instantly.

Contingency Plan
VoIP handles emergencies with ease. You get business continuity enabled and you can reroute calls to backup sites in seconds.

Simple and easy to manage

Like many SaaS-based tools, cloud telephony gives you and your team the ability to use your own devices to make business calls and manage it all from a central location.

Future-Proof Solution

Voice is well-mapped out and ready for voice/data convergence. It’s the way forward – get on board.


Every organisation is different and so are your needs. That’s why we support you to make a tailored decision about the future of your business communications. Whether you’re looking for an on-premise communications platform, want Session Initiated Protocol (SIP) connectivity or are thinking about moving to a fully-hosted cloud infrastructure, we’ll help you get there.

We will take care of the porting process for you, managing the entire process of switching from ISDN to IP, so that you and your business won’t experience any loss in service during the changeover. All you have to do is let us start …



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