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Prepared for the BT ISDN Switch Off?

Are you ready for the UK’s BT ISDN Switch Off coming in 2025? Get a head start and futureproof your business today.


* Time until the ISDN Switch off begins (the full switch off expected in December 2025).

SIP Phone Lines


What is happening?

BT are switching off the UK’s PSTN and ISDN networks for good in 2025. This means that any business phone or service that operates of the old analogue network will be switched off.

The BT switch will affect thousands of businesses, especially those unaware of BT’s intention to phase out of technology. Traditional ISDN phone lines are a legacy technology with high maintenance costs and many drawbacks.

In light of the BT ISDN Switch Off, on 5th September 2023 a STOP SELL was implemented making it impossible order any new traditional ISDN services or make any changes to existing services.  By 2025 it is a requirement to totally upgrade to IP telephony to avoid interruption to your telephone services.



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It is estimated that only a fraction of UK businesses are aware of the ISDN switch off with only a third of smaller businesses and less than 10% of larger enterprises proactively adapting to the transition to IP-based systems.

Source: Sensuswide


What Is Being Switched Off and When?

Relating to the BT ISDN Switch off, two concurrent initiatives are underway: the Full Fibre Priority Exchange Programme and the phasing out of analogue services dependent on copper lines, namely PSTN and ISDN.

Both projects are scheduled for completion by 2025, with the Fibre Exchange aiming to achieve 85% broadband coverage by the end of that year. However, the implementation of these initiatives is already heavily underway.

Benefits of UK ISDN Switch Off

Reliable and faster broadband.

Full fibre broadband is up to 5x more reliable and 25x faster than traditional copper line-based broadband used prior to the BT PSTN Switch Off.

Better collaboration.

A unified comms infrastructure using platforms like Microsoft Teams and CRMs such as salesforce, streamline business processes and facilitate collaboration and innovation.

Improved efficiency.

Digital voice services and cloud-based phone systems are more scalable, and efficient, as well as being budget-friendly.

More sustainable.

Full fibre connectivity is more energy-efficient and requires less resources than PSTN lines, making for a more sustainable communication infrastructure.

" An amazing, professional, above and beyond service. Where our old suppliers were terrible and misleading, Birmingham Telecom have been extremely helpful and forthcoming with any issues or charges that we would incur. Can highly recommend this company. "

David Edwards

Prime Facility Services


Why Work With Birmingham Telecom for the UK's ISDN Switch Off?

Eliminate the unnecessary hassle by entrusting us with your changeover process. We will take care of everything, ensuring a smooth and seamless transition that minimizes any disruptions to your day-to-day operations.

Benefit from our team of skilled experts based in the UK, as we provide robust technical support to all our clients. By partnering with Birmingham Telecom, you can stay ahead of the UK’s ISDN Switch Off and stay one step ahead in the evolving communications landscape.


We Partner With Only The Best

Our reputation has remained flawless during the 17 years of trading and continues to depend upon the solutions we provide. We have developed trusted, long-term partnerships with many of the market-leading technology vendors to deliver secure, future proof communications solutions to our clients.

The ISDN switch off refers to the planned phasing out of Integrated Services Digital Network (ISDN) services by BT Openreach. It involves the transition from traditional ISDN-based voice communication to modern, internet-based technologies like Voice over Internet Protocol (VoIP), fibre to the premises (FTTP) and other digital alternatives.

The ISDN switch off is happening in 2025, means a full transition from analogue to digital technology and there is no way to avoid it

BT announced that the UK ISDN Switch Off and PSTN Switch Off will take place in two phases.

The first phase

This involves a “a stop sell” of new services and begins on 5th September 2023.

This stop sell prevents telephone providers from placing PSTN single line orders, PSTN multi line orders plus any order for  ISDN2, ISDN30 and ADSL, FTTC and G.Fast broadband products.

When this deadline is reached you will no longer be able to :-

  • Transfer any legacy services “Like for Like” between suppliers (PSTN, ISDN ADSL or FTTC)
  • Place an order to take over a working line
  • Restart a phone line that is currently “stopped” ie. when you move into a new property with a phone socket on the wall
  • Amend your ISDN DDI range
  • Increase or decrease your ISDN channels
  • Convert single analogue lines to multi lines or ISDN
  • Amend select services on any phone line
  • Add Broadband (ADSL and FTTC) to PSTN lines
  • Migrate to non-ultrafast broadband products

The second phase

The complete withdrawal of ISDN and PSTN services is scheduled for September 2025.

This means that any of the services that rely on this technology will be switch off when this deadline is reached.

Anyone that relies on either PSTN or ISDN technology must upgrade before the final deadline.

The UK Switch off will affect business using either ISDN or PSTN technology.

Most commonly, the following services use either analogue or ISDN phone lines and need to be upgraded.

  • Analog telephone lines and voice calls made through PSTN or ISDN will be affected. Both businesses and residential customers will need to migrate to alternative voice services such as Voice over IP (VoIP) or digital telephony solutions.
  • Fax machines that rely on PSTN or ISDN connections for sending and receiving fax messages will need to be replaced or upgraded to digital alternatives.
  • Alarm systems that utilize PSTN or ISDN for monitoring and communication, such as burglar alarms or fire alarms, will require alternative methods of connectivity. Alarm system vendors should be contacted to explore options like cellular or internet-based monitoring.
  • Payment card machines that use PSTN or ISDN lines for transaction processing, such as point-of-sale (POS) terminals, may require migration to IP-based payment solutions or newer card readers that support IP connectivity or a mobile SIM.
  • Emergency services such as medical alert systems or emergency call points, may be affected by the PSTN switch off. If you use these services, please contact your providers as soon as possible to ensure continuity through alternative communication methods.
  • Electronic Point of Sale (EPOS) systems that rely on PSTN or ISDN connections for real-time transactions and reporting may need to transition to IP-based or wireless solutions to maintain functionality.
  • Lift emergency phones that operate on PSTN or ISDN networks will require migration to alternative communication technologies, ensuring uninterrupted access to emergency services.
  • Telecare services that use PSTN or ISDN for remote monitoring and support for elderly or vulnerable individuals may need to switch to alternative methods such as mobile or internet-based solutions.
  • Conference calling systems utilizing PSTN or ISDN lines for audio conferencing may require migration to VoIP-based conferencing solutions or online meeting platforms.
  • Some broadcast services, such as radio station phone-ins or call-in shows, that rely on PSTN or ISDN lines for live interactions with listeners may need to transition to digital platforms or VoIP-based call-in systems.


It’s important to note that your own specific service provider may already offer alternative solutions or guidelines. If you need any help or need advice relating to any of these services, please contact us on 0121 716 8888.

The ISDN switch off is happening for several reasons.

One primary reason is the advancement and widespread adoption of digital communication technologies that offer better efficiency, flexibility, as well as being more cost effective for all involved.

Additionally, maintaining and supporting outdated ISDN infrastructure has become increasingly expensive for BT Openreach which makes this transition to digital voice necessary.

The ISDN switch off will require businesses to transition their ISDN phone services to alternative technologies.

This transition may involve upgrading to Voice over IP (VoIP) systems or a cloud based telephone system but ultimately, businesses will need to ensure compatibility, assess their needs and plan for the ISDN switch off to avoid disruption to their telephone services.

Whilst daunting when first thinking about the ISDN Switch off, migrating from ISDN to modern telephony offers several benefits and future proofs your business.

These benefits include significant cost saving, increased flexibility, improved homeworking capability, enhanced features (at no additional cost) as well as overall improved call quality and a better level of service from your provider.

Although the switch off is happening in December 2025, we highly recommend that you get a head start and switch over as soon as possible.

Businesses will be unable to order new PSTN or ISDN services following the “Stop Sell” in September of 2023 and therefore this could cause disruption to your business.

To prepare for the ISDN switch off, would would strongly recommend taking an early, staged approach when considering your options.  Whilst most small businesses can be migrated quickly, larger projects need planning and can take time.

  1. Evaluate your current communication infrastructure and identify how ISDN is being used in your business.
  2. Get advice on how alternative technologies such as VoIP, cloud hosted telephone system and digital telephony systems can help you.
  3. Engage with a service provider like Birmingham Telecom in order to understand your migration options and timelines.
  4. Plan the transition process, including assessing hardware and software requirements.
  5. Ensure that your employees are trained on the new technology, the new systems and tools implemented.
  6. Test the new solution and ensure compatibility with existing applications and services.
  7. Implement an early, phased migration strategy to minimise disruption to your business.

Emergency services and alarm systems that rely on ISDN connections will be impacted by the switch off.

Whilst it is rare we come across any business that uses ISDN for their alarm services, this is still a valid question and will likely impact some companies.

Most alarm providers are already aware of the impact the BT switch off will have and for years have already been working on alternative solutions to ensure the continuity of critical services.

If you feel like you could be affected, we would recommend that you contact the respective alarm system supplier to discuss your migration options and any necessary upgrades.

Yes, you certainly can.

Going digital does not mean your business has to lose its established phone number. When you switch to us, you’ll be able to make calls on any device and from anywhere on the same phone number. Want to change numbers to something a bit more on brand or have a new non geographic number? No problem, because you can do that too.

It is always important to consult with any new service provider to understand their number porting procedures and ensure a seamless transition.  The process we use is known in the industry as “number porting” or “number transfer” and is a standard service we offer for pretty much every customer we work with.

In a nutshell, the ISDN Switch Off primarily impacts voice communication services rather than internet connectivity.

That said, there are still some businesses we come across that still use ISDN for data (their internet connection).  This is a legacy technology that offers extremely slow download speeds and it has been outdated now for many years.

Any business customer that is still using ISDN for data services should immediately assess their internet connectivity options and consider upgrading to full fibre or a dedicated leased line alongside their voice migration.

We find that in most cases, the transition from ISDN to digital voice is quick and simple (of course when handled correctly).

That said, we would recommend that you don’t overlook potential challenges you may face when migrating away from ISDN.  These include ensuring compatibility of new technologies with your existing infrastructure, training your team on the new systems and working with a partner who can handle the migration process without disruption to your day-to-day operations.

When you discuss the ISDN switch off with Birmingham Telecom, we always like to have a detailed discussion with you either over the phone or if possible, face-to-face which will allow us to get a feel for your work environment and how you currently use your existing legacy systems.

Absolutely.  We would strongly recommend that you at least consider your options sooner rather than later.  You should start planning and make the migration well in advance of the ISDN switch off date to avoid disruption later.

It is estimated that over 65% of small businesses are still not aware of the ISDN switch switch could lead to a huge influx of people trying to switch to digital voice closer to the switch off date.  If this happens there of course will be huge demand placed on BT Openreach who lay and install the infrastructure whilst service providers like ourselves will be swamped with orders which could cause delays! 


We have already helped over 1,000 UK businesses with the PSTN and ISDN Switch Off.

Get your FREE PSTN Switch Off review and take the first step in ensuring you are ready for the big ISDN Switch Off.

Get your FREE BT ISDN Switch Off Review! Call us on 0121 716 8888

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