The ISDN Telephone Switch-off: Everything You Need to Know

The way UK businesses access telephony services is changing. In 2025, the UK’s ISDN network will be switched off, along with a range of analogue services, so you’ll need to act soon to ensure you’re ready for this.

Watch the ISDN Switch-off video below to learn what's happening and what you should do about it.

Openreach ISDN Telephone Switch-off: What are your options?

Are you ready for the ISDN Switch-off?
Learn more with our FREE White Paper

With sales of ISDN being stopped from 2023, businesses can’t afford to put this off. Openreach believes some 16 million lines will need to be moved into more modern solutions, so taking the time now to plan for the future and ensure voice and other phone-dependent services are secure for the digital-first era will be vital to the success of any business, no matter how large or small.

Topics covered in the ISDN Switch Off White Paper: 

  • Which alternative services are available?
  • How to go about migrating your services.
  • The benefits of SIP Trunking or cloud telephony solutions.
  • Which services are being switched off.
  • Why the switch-off is being made
  • Which systems will be affected
  • The challenges and opportunities this will present to businesses.

Download this
White Paper Now!

Commonly affected Systems

It’s important you act quickly to determine what services may be affected by the switch-off, as this technology goes beyond just voice. 

Openreach believes upgrading customers onto its new, ‘full fibre’ network will future-proof the digital economy and boost productivity.

If you use any of the following solutions, you may also need to start planning a migration now: 

  • Card machines
  • Emergency alarms
  • Lift-lines and help point systems
  • Door entry systems
  • Fax machines
  • Remote monitoring equipment

Contact our expert advisers for more information on what to do next:

'WLR Stop-Sell' from Jun-Oct 2021

Whilst the 2025 switch-off date is still a few years away, Openreach advanced the closure of services across 169 exchanges. 

Included in this list are locations such as Salisbury, Broadstairs, Bromsgrove, Doncaster, Orpington and Penzance.

The first Stop-Sell was made effective from the 1st December 2020 in Salisbury.

Click below to learn more about the early STOP SELL and see the full list of exchanges. 

If you are looking for alternatives to ISDN,
consider our Cloud Technologies

Our Cloud Solutions are tailored to suit every business, from small (< 25 seats) to large (1000’s of users) and include a full enterprise feature set with best of breed complementary applications. All of our Cloud Technologies are fully deployed, managed and maintained by Arrow support teams. 

Click below to learn more:

The ISDN telephone switch-off: Why you need to take action now

  1. Introduction: The need to upgrade your phone lines

Telecoms is a vital part of any business. But if you’ve been stuck using the same legacy phone lines for your voice calls or other key office technology functions for many years, the chances are you won’t be making the most of what the latest technology can offer.

However, there is an even more compelling reason for firms to upgrade their telephony solutions sooner rather than later. That’s because there is a major change coming in the communications market in the coming years – the switch-off of ISDN and analogue phone networks.

ISDN, which stands for Integrated Services Digital Network, is a set of standards for voice and data communications, which allows a single telephone line to carry not only voice calls, but also video and data. For many firms, this is likely to be the backbone of their phone network, with many phone lines reliant on this technology

The switch-off is set to take place in 2025, so if you’re still using ISDN or other legacy tools, the clock is ticking. It might seem like this is still a long way away, but you have less time than you may realise to evaluate your options and secure the technology you need for the future.

However, awareness of the coming change is still low and many firms, particularly smaller businesses, may find themselves confused by what will be required of them and what options are available. So what do you need to know about the switch-off and the impact it will have on how your firm communicates?

  1. The coming ISDN switch-off

The decision to switch off older telephone systems comes from network operator Openreach, which is aiming to migrate people away from older, less reliable communication technologies and on to digital services such as VoIP. This means many technologies that businesses have relied on for many years will no longer be available.

What’s changing and why?

The system that is being retired is the Public Switched Telephone Network (PSTN), which is a series of copper telephone lines, fibre optic cables, microwave transmission links, satellites, undersea telephone cables and mobile networks that allow for calls to be made using analogue voice data. Currently, the plan is for this network to be withdrawn at the end of December 2025, with affected products no longer being sold after 2023 in preparation for this.

There are a number of issues with this network, with Openreach noting that in addition to ageing, unreliable technology, the system is becoming difficult to maintain, as many of the necessary spare parts are no longer being manufactured. What’s more, the firm explained that “many of the people who designed, built and operated the system are retired or close to retirement so skills are increasingly scarce”.[1]

PSTN supports a number of Openreach products that are collectively known as Wholesale Line Rental (WLR) products, which is why you may hear the switch-off referred to as the WLR withdrawal. These products include the likes of WLR3 analogue, ISDN 2 and ISDN 30, which are likely to be the backbone of many firms’ voice communications systems.

Tools like on-site PBX will be among the most commonly-affected solutions for many businesses. However, voice calls are not the only systems set to be affected by the move. Many small and medium-sized firms will use these phone systems for other uses, including card machines and alarm lines, so firms will have to take these elements into account when considering a migration.

Moving to a more capable future

The move to a fully digital communications network in the UK may be seen as long overdue. Indeed, many of our European neighbours are already much further down the road to a digital future, with France scheduled to complete its migration by the end of 2020, and Germany already having switched off analogue networks at the end of 2018.

A digital-first environment should not only be more reliable than existing copper-based lines, but will create a range of new opportunities for businesses to access more advanced features and support more specialist services. For businesses, it should encourage them to look at technologies such as cloud telephony and SIP services.  In addition to this, many firms will need to consider their data solutions if these currently run over traditional broadband or FTTC via an analogue line.

A SIP solution will replace an ISDN connection and connect firms to communications networks over the internet. This can bring a range of benefits to businesses, including lower costs, improved flexibility and greater freedom when it comes to your phone lines, including virtualised numbers, automatic redirection and much greater resiliency.

  1. What the migration means for your business

The switching off of ISDN and other outdated communications products will mean a major migration will be needed. In total, Openreach believes some 16 million lines will need to be moved away from WLR products to more modern solutions.

James Lilley, head of copper and service products at Openreach, likened the challenge to the move from analogue to digital TV services in 2007. However, while that process was phased and had the backing of millions of pounds of government funding, the migration away from the PSTN network will be industry-led.

So far, around a million users have migrated away from the PSTN since the switch-off was announced in 2018, but there’s a lot more work to be done to raise awareness and help businesses understand their options.

Mr Lilley said: “It’s about to get quite real with a lot of this stuff. We are really trying to get the message out there.. we’ve made good progress but we’re not there yet, as we’re still coming across [people] who are hearing this for the first time.”[2]

The challenges for business

Leaving migrations late should not be an option for any UK business that wants to ensure continuity in its operations once services such as ISDN have been withdrawn. While December 2025 may feel like a long way away, it will be upon us sooner than many businesses realise.

Indeed, there are lessons to be learned for the UK from the experiences of other countries. In Germany, for example, some businesses did not take action until very late, leading to an “ISDN panic” as the deadline approached and firms realised too late they had not adequately prepared.

Axel Klössner, Chief Operating Officer and International Business Director at German vendor Auerswald, commented: “A number of German businesses that were not aware of this change and how it affects them are in a state of panic as they heavily rely on their ISDN service to function. This can drive business owners to make quick decisions about something which could have a long-term costly impact on their sustainability.”[3]

Companies will also need to think beyond their own office. The switch-off may well also affect home and remote workers who currently rely on consumer-grade analogue phone or broadband systems, and businesses will have a responsibility to account for these workers as well in any migration.

The steps to a successful migration

It’s therefore clear that to avoid making any rash decisions, UK businesses need to act now while there is still time to fully evaluate the options that are available. This ensures they will be able to prepare properly for any impacts the migration may have on their business, such as working around any downtime that may be necessary during the process.

To achieve this successfully, it will be important to work in partnership with an experienced partner. Openreach is taking the view that the migration should be industry-led, with it encouraging communications providers to take proactive steps to engage with customers and help them understand what they need to do.

This will be especially vital for the many firms who may lack the technical knowledge to navigate the migration themselves. This will likely include smaller companies and sole traders who may still be using telephony solutions bought years ago from consumer retailers, and now face a complex move to digital IP-based technology they may not fully understand.

There’s no set roadmap for how to complete a migration, and the services that are available and most appropriate for a business will be dependent on a number of factors, including the geography in the firm’s local area, the size of the business and how many locations they need to connect to a new system.

It will first be important to establish how existing services will be maintained and disruption kept to a minimum throughout the process, then carefully assess the merits of the various available options, including flexibility, scalability and what ongoing costs are expected.

  1. Cloud telephony: futureproofing your firm


The answer to many firms’ communications needs in the coming years is likely to be SIP trunking and cloud telephony. These technologies are expected to be the number one option for replacing ISDN networks, providing businesses with an affordable, reliable IP-based network that should serve them well for many years ahead.

What do SIP services offer to firms?


Standing for Session Initiation Protocol, SIP services use VoIP technology to provide connectivity between your phone systems and the wider network. Working within a business, or in combination with cloud-based hosted telephony services, these will be a primary consideration for many firms, as they offer a wide range of benefits over ISDN lines.

As well as being more affordable and reliable, this technology offers a much greater degree of flexibility and scalability, enabling users to add new seats quickly and easily whenever they are needed. The technology is simple and non-disruptive to install, and allows you to retain local numbers regardless of where your firm is based.


Most cloud telephony solutions now have SIP trunks included in the package.  However, some firms may want to enable their current PBX for SIP to make the transition to full hosted telephony at a later date.


Addressing the future needs of businesses


One of the most important factors for any business when they’re looking to migrate to any digital telephony service is the ability to move their numbers with them. This will be vital for any firm, but especially so for those with a local presence where customers and partners expect to reach them on the phone regularly.

Moving to a whole new set of numbers will be a costly and complex process, not only within the migration itself, but any extra expenses that come along with it, from amending documentation and signage to publicising any changes. It could also lead to lost revenue as existing customers and those still using outdated information find themselves unable to contact a company, so take their business elsewhere.


Cloud hosted telephony and SIP services offer a variety of solutions to ensure businesses can keep all of their existing numbers, while at the same time giving them greater flexibility to add more users, take advantage of virtualised numbers and manage challenges such as seasonal variation in demand.


Cloud telephony systems ensure that whatever the future may bring for your company, your communications solutions can easily adapt to handle it. Whether this is adding new seats or entire new locations, or maintaining business continuity by letting you easily reroute calls in an emergency, these tools will support whatever you need to do in the years to come.

This is also another good reason to make an early transition as more and more companies look to ‘port’ their numbers into the cloud, which is putting strain on the Ofcom regulated Number Portability facility, causing potential backlogs.


  1. Understanding the available options


In order to ensure the migration away from ISDN and analogue solutions goes smoothly, it’s vital to have a clear understanding of what options are available. This should not only cover voice services, but any other communications infrastructure that will be necessary to keep businesses running.


The technologies on offer


If customers are looking to ensure their communications are fit for the future, relying on a full fibre network is likely to be the best solution, as this provides more bandwidth and faster speeds that should be robust enough to cope with the expected increases in traffic demand in the coming years.

Full fibre ensures both voice and data services can deliver the highest possible level of performance, but this is restricted by the fact it is not yet available everywhere. However, many smaller firms may be able to get financial assistance to access this technology through the Government Broadband Voucher Scheme, which offers grants of up to £2,500 for small firms looking to upgrade their connectivity.

Therefore, it may well be worthwhile investigating this when looking to upgrade phone services in order to secure the future of their entire communications package. This ensures the entire infrastructure is fit for the future and makes it easier to manage any other issues that may be part of a migration, such as the need to move IT equipment to new IP addresses.

For those who aren’t able to access this technology, there are alternatives available, such as  SOGEA and SOGFast. These technologies, standing for Single Order Generic Ethernet Access and  Single Order G.Fast respectively, use upgrades to existing connectivity tools to offer advanced communications services for businesses that can’t access full fibre, while even newer ways of obtaining coverage such as 4G and 5G routers may be considered.


Making the right decision for your business


Cloud telephony isn’t a one-size-fits-all solution. There are a range of options available to businesses that may be more appropriate for certain situations than others. For instance, some solutions are better-equipped for smaller firms with just a couple of users, while others are tailored more specifically to medium-sized firms that may have more users spread out over two or more locations.


Arrow offers two key cloud telephony solutions – Scala and Horizon – to meet the needs of any small and medium-sized business. Both provide a complete hosted communications service that incorporates cloud telephony as part of a unified communications service, with Horizon aimed at smaller organisations and Scala for those with 25 seats or more.

The option you choose could set the standard for your communications for years to come, so it’s important to take the time to evaluate your options and consult with expert partners to ensure you’re making the right decision.

This can also help you establish what other services you’ll need to look at migrating. Card machines, emergency alarms, lift-lines and help-point phones, door entry systems, vending machines, fax machines and other remote monitoring equipment may all rely on analogue phone services that will be withdrawn as part of the switch-off.


  1. Making the transition – what should the next steps be?


With the clock ticking on the countdown to the ISDN switch-off, it’s imperative businesses act now to ensure their transition away from this technology goes smoothly. This can be a complex task, especially for small companies with limited experience and expertise in this area, which is why it pays to seek out advice from a trusted communications provider.

The first step for any business that is worried about how they may be affected by the switch-off, or is unsure about what their options are, is to arrange a consultation with their communications provider. This should help to identify what services will be affected, and what the best route forwards will be.

With sales of ISDN being stopped from 2023, firms can’t afford to put this off. Taking the time now to plan for the future and ensure voice and other phone-dependent services are secure for the digital-first era will be vital to the success of any business, no matter how large or small they may be.

Contact Arrow Business Communications today on 0330 440 4444 or [email protected] to find out more about your options for migrating services away from ISDN systems.