ISDN Switch Off | Key Dates & Information | NBC

The ISDN Switch Off: Key Dates and Who is Affected

April 21, 2023

BT stopped the purchase of ISDN lines in 2020 and will switch off all lines in 2025. Modern technology means that legacy landlines are becoming outdated, while the costs involved with maintaining PSTN/ISDN are inefficient in the digital age, particularly considering the convenience of VoIP (Voice over Internet Protocol) systems.

As we draw nearer to the switch off, homes and businesses are learning more about what’s involved and preparing to make the change. In this comprehensive guide, we’ll cover what ISDN is, why it’s switching, key dates, who’s affected, and more, helping you stay ahead with the most up-to-date communications systems.

What is ISDN?

Integrated Services Digital Network (ISDN) is a telephone network system that transmits data, voice, video, and more over the digitalised circuits of the Public Switched Telephone Network (PSTN). It can be thought of as a set of communication standards that uses digital transmission to perform a range of network services.

Designed to modernise landline technology, ISDN was first introduced by BT in 1986, replacing outdated landlines with digital lines, and introducing a range of new features that were hitherto unavailable. Since, ISDN connections have been known for their high speeds and reliable connectivity.

However, new technologies better suited to the demands of the modern world have heralded the ISDN switch off.

What is the ISDN switch off?

The ISDN switch off refers to BT’s plan to gradually phase out ISDN, with the ultimate goal of switching the lines off in 2025.

In 2015, BT announced that more ISDN lines would be available to purchase in 2020, with the longer-term plan of officially switching off the copper-based PSTN and ISDN networks in 2025.

This comes as part of a goal to transition into digital networks worldwide. In addition to business and home phone lines, it’ll also affect other services that use ISDN lines, including:

Ultimately, any devices that utilise ISDN will no longer function, and businesses and individuals will require handsets that are compatible with internet protocol (IP) technology to transmit voice in digital formats when making and receiving calls.

Why is ISDN being switched off?

ISDN is being switched off because it’s outdated. There are now more modern systems available that provide better business communications, and it doesn’t make financial sense to continue making improvements to the ISDN network.

ISDN relies on the digitalised circuits of the PSTN, a network that’s barely changed in response to the increasingly digital and dynamic world. Hyper-connectivity is a keystone of the modern world, and since neither ISDN nor PSTN technologies have the capacity to handle the sheer volume or quality of data they’re now exposed to, more advanced solutions are required to maintain quality communications.

ISDN switch off: Key dates

Key dates for the ISDN switch off are as follows:

What are the risks of the ISDN switch off for businesses?

The risks of the ISDN switch off only apply to businesses that don’t transition to a VoIP-based system in time. If your business isn’t up and running your communications on an internet-based system by December 2025, it’s highly likely that you’ll face roadblocks, extra expenses, and missed opportunities as a result of dealing with a defunct system. Poor communications will undoubtedly impact the bottom line, harm customer relations, and create confusion within your organisation, so it’s essential you act fast to ensure your company is fully prepared for the switch.

What will replace ISDN?

Digital phone lines that route calls using IP technology will replace ISDN lines. In a modern world where demands on communications are huge, IP systems are far better equipped to process large volumes of data that are commonplace in everyday business. Plus, as mobile and internet communications become more ubiquitous, embracing them to support further data transmission is a natural, convenient, and affordable next step.

Are there any alternatives to ISDN?

As all traditional phone systems will be affected, any business that uses them will need to switch to an internet-based or hosted VoIP phone system. Two alternative systems are:

Fully hosted systems are generally more flexible, making them a popular choice for businesses. Learn more about hosted and SIP solutions in our guide.

How do I get replacement PSTN products and services?

Openreach products will be available as a Single Order variant of ADSL or Fibre broadband services. To use these services, you’ll need to ensure you have access to the relevant equipment and a communications provider

What contracts are available for VoIP phone systems?

VoIP phone systems are generally available on monthly or yearly contracts. They’re a lot cheaper than traditional phone lines and, as they utilise the internet to function, require much less maintenance. 

What lines will the ISDN shut down affect?

The ISDN shut down will affect all lines supported by PSTN, including:

If your business still uses any of these lines, it’s time you prepare to upgrade.

What should I consider before the ISDN switch off?

The main thing to consider before the ISDN switch off is which VoIP or fully hosted PBX system you’re going to upgrade to. If your business is looking to reduce maintenance and IT staff time, a fully hosted PBX system is likely your best choice when it comes to minimising upfront costs. 

What does my business need to do?

Once you’ve decided which system to upgrade to, there’s not much you’ll need to worry about. It’s likely your SIP trunk provider will be able to upgrade your current system, meaning you won’t need to spend time and money starting from scratch, and will make transferring existing numbers a seamless process.

Just be sure to check that your internet connection is strong enough to deal with your new, upgraded network to avoid any roadblocks. Learn more internet speeds in our guide, and view our superfast business broadband deals to find one that suits your needs.

How do I know which system to upgrade to?

Ultimately, the best system for you to upgrade to will depend on your unique business needs. Different systems come with a range of features and benefits, so your best bet is to speak to an expert who can offer advice on which solution is best for you.

If you have any questions, don’t hesitate to contact us on 0330 311 1133. You can also view which phone line is best for your business in our guide.

How do you switch from ISDN to VoIP?

Before switching to VoIP, identify your business requirements and decide on the features that you’ll need from a phone system to guarantee quality communications. Next, get in touch with the providers that can offer this service and determine which one best suits your company. From there, VoIP providers will be able to offer support and guide you through the process step-by-step. 

At NBC, we offer quality products and services at affordable prices. We’re experts in the field, and our helpful team have plenty of experience supporting companies through the switch. Don’t just take our word for it – see what our customers had to say about us!

Learn more about why to choose NBC, and view our impressive VoIP phone system packages today.

Frequently asked questions

What is WLR withdrawal?

WLR withdrawal refers to the process of phasing out traditional copper phone line services in the United Kingdom. Openreach, the UK’s largest provider of phone and broadband infrastructure, plans to withdraw over 16 million copper phone lines by the end of 2025. This means that customers who currently rely on copper phone lines for their home or business phone service will need to switch to alternative technologies.

What is Session Initial Protocol?

Session Initiation Protocol (SIP) is a signalling protocol used to enable Voice Over Internet Protocol (VoIP) services. It works by defining the messages that are sent between endpoints and managing the various elements involved in a call. With SIP, it is possible to support not just voice calls, but also other multimedia services such as video conferencing, instant messaging, and media distribution.

What is a fully hosted phone system?

A hosted phone system allows phone calls to be routed through your business’s broadband connection, rather than via traditional telephone lines. It is also sometimes known as a VoIP system (Voice over Internet Protocol) or a cloud-based phone service.

Is ISDN still used in the UK?

Many businesses still use the ISDN system, so it’s essential they upgrade in advance of the ISDN switch off in December 2025.

Are BT switching off landlines?

The ISDN switch off means that landlines with no internet connection will no longer be able to make calls after December 2025.

When did BT announce the ISDN switch off?

BT first announced the ISDN switch off in 2015.

What is VoIP?

Voice over Internet Protocol (VoIP) turns audio signals into digital transmission data that can be sent through the internet. VoIP software allows users to make calls over the internet without the need for a traditional phone line, and will soon take the place of physical phone systems.

Learn more in our guide to VoIP.

What are the benefits of VoIP over ISDN?

Benefits of VoIP systems over ISDN lines include:

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