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Learn The ISDN Switch Off

What it means for your business

Written by Millgate 06/11/2020

Who and what?

BT has announced that you will soon no longer be able to purchase new ISDN lines, and that these lines will eventually be switched off completely.

The changes will impact all organisations using physical ISDN – Integrated Service Digital Network – telephone systems. Many of those organisations installed ISDN as an alternative to dial-up connections for higher internet speeds, and they may still be installed in areas without access to broadband internet.

However, this technology has been surpassed by modern alternatives and is now being phased out.


When and Where?

The ISDN switch off will cover the whole of the UK, where it is estimated over 2 million businesses are still using the technology first introduced in 1986.

While the switch off won’t start until April 2025, you will no longer be able to purchase new ISDN lines from September 2023.

Therefore, if your telephony contract is coming up for renewal in the next few years, we recommend you don’t wait to research the best alternatives for you.



To put it simply, the technology is obsolete and far surpassed in both quality and convenience by newer, internet-based alternatives.

The move confirms that ISDN lines no longer offer value to businesses and are in fact costing many of them time and money in efficiency. The same is true for BT, who no longer want to maintain a service that is of no benefit to anyone.


How does this affect me?

This depends on two things. First, whether you’re running ISDN lines. If your phone system was installed more than three years ago and grants you the capability of taking multiple calls at a time, it’s probably using an ISDN line.

If you’re not sure what you’re using, we can quickly tell you as part of our free comms consultation.

The effect also depends on how quickly you respond to the ISDN switch off.

Many businesses will see it as something not to worry about for five years. We believe this is a mistake. Migrating your telephony is a major project, and the last thing you want is to sign up to the wrong contract in a panic and get stuck with inadequate systems for years.

We recommend working with a specialist telecoms provider, who will understand your business requirements and advise on the right solution to meet them. Be wary of pressure from providers who rely on you rushing or not fully understanding the impact of the upcoming changes.

As has been proved time and time again, those who get ahead of the curve also get ahead of their competition. Proactive businesses will not only breeze through the ISDN switch off in 2025, secure in the knowledge their phone system is fit for years to come, but they will also enjoy the benefits of superior telephony from the time they upgrade.


What should I upgrade to?

Voice over Internet protocol (VoIP) telephony will ultimately supersede all phone lines, and BT’s focus is now moving to this future-fit technology. VoIP uses an active internet connection to make voice and video calls without the need for traditional landlines. A cloud-based or hosted option is ideal for businesses that don’t want to commit to an on-premises phone system, which is understandable in our remote working world.

VoIP phone systems offer simple scalability without heavy maintenance charges. However, on-premises options are dependent on a fast internet connection to ensure strong service and good audio quality. Additionally, your existing phone system must support VoIP. If it doesn’t, and you don’t want to invest in an on-premises solution, you may want to move to a hosted VoIP service.

For those committed to enhancing their on-premises phone systems, VoIP with SIP offers advantages including cost savings, resilience and flexibility. SIP is a formal signalling protocol that uses VoIP to deliver real-time calls, messaging and video conferencing, unlocking the possibility of truly unified communications. However, SIP requires hardware investments in routers and devices plus other IT support to deal with any problems that arise.

Hosted VoIP requires no on-site installations, instead using a softphone to allow users to access their phone number on any device, and therefore the upfront investment is low. For organisations fulfilling their video conferencing and messaging needs through other means, hosted VoIP may be more suitable than SIP.


How do I know what’s right for me?

Ultimately, the right IP phone system for you will depend on your business’s size, location and growth. While traditional VoIP and SIP systems offer different capabilities and advantages, they each come with certain requirements or restrictions. This is why it’s so important to start planning for the ISDN switch off now.

While you might not immediately know what upgrade is best for you, you can be confident that your existing ISDN lines are no longer fit-for-purpose. The ISDN switch off is coming, and you want to ride the wave of evolution instead of being wiped out by it.

We see the change as a positive one. Very few businesses were completely equipped for the transition to remote working in 2020, and this was in large part due to a reliance on outdated telephony technology. Businesses already using some form of VoIP telephony were able to respond much more rapidly, and the flexibility their phone system provides guarantees they will continue to be futureproofed for a long time.

With business benefits including affordability, easy maintenance and freedom to scale, VoIP telephony systems are helping forward-thinking businesses to accelerate into the second quarter of the 21st century.

If you want to be one of those forward-thinking businesses, work with a provider you can trust to manage the migration process, and don’t be pressured into a decision you don’t fully understand.

At Millgate, our mission is to help clients succeed by delivering technology that actually works, so we promise to take the time to truly understand your requirements and advise on the right solution for you. And as one of the only companies in the UK to offer both IT and telephony services, responding to the ISDN switch off with Millgate is the perfect opportunity to achieve truly unified communications across your business.

Find out more about our free comms consultation for Millgate clients


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