The PSTN and ISDN switch-off: Everything you need to know
Most of us in the UK don’t give a second thought to the complex telecommunications infrastructure that connects us. However, that’s about to change as a system based on copper wires, dating back to the late 1800s, is on the verge of being shut down. While landlines and associated systems will still exist, they’ll operate on more modern, internet-based technology. If you’re not prepared for the transition, your business could face some unpleasant and potentially debilitating surprises.
The PSTN switch-off, is scheduled for 31 January 2027. That’s when Openreach, which maintains the BT network, will abandon this increasingly outdated system. The public switched telephone network (PSTN) and integrated services digital network (ISDN) will go the way of wax cylinder phonographs and computer punch cards. Other countries, such as Estonia and the Netherlands, have already phased out the technology.
Will the switchover go smoothly in the UK? That all depends on business owners like you. If you’re not careful, the equipment you rely on could let you down without warning.
In this article, we'll be explaining what these networks are, how they’ve outlived their usefulness and why you should start thinking about the necessary transition right now.
Table of contents
- What do PSTN and ISDN mean?
- What is the PSTN switch-off?
- How will this affect you?
- Key switch-off dates
- Ready to move to the cloud?
What do PSTN and ISDN mean?
What is PSTN? The Public Switched Telephone Network refers to traditional analogue phones—landlines connected by wires via switchboards. While it has evolved since Alexander Graham Bell invented the telephone, its fundamentals have remained unchanged since the 19th century.
What is ISDN? Also known as the integrated services digital network, it uses old-fashioned phone lines to transmit sound, data, and video information in a bundle. BT introduced this technology in 1986, and the public has long since switched to some form of broadband. Nonetheless, businesses still use ISDN connections for devices such as fax machines, credit card readers, legacy voice and PBX systems.
The plain fact is that both PSTN and ISDN have been superseded. In a sense, they’re throwbacks to the 20th century in that they lack the necessary bandwidth for modern technology. From a commercial standpoint, it’s also disproportionately expensive for the operators BT, Virgin Media, and KCOM to maintain their underground and overhead wires.
Alternatives such as broadband telephony—technically known as Voice over Internet Protocol, or VoIP—and SIP trunking (short for Session Initiation Protocol) represent the clearest way forward. In a world of teleconferencing, mobile communication, cloud storage, and working from home, VoIP stands out as the successor technology. In addition, it’s cheaper and more flexible than the soon-to-be-defunct alternatives.
What is the PSTN switch-off?
BT announced in 2017 that it would phase out PSTN and ISDN. Over the past few years, it has stopped selling these legacy phone lines and analogue products region by region. Continuing to support them no longer makes financial sense—finding parts for legacy systems has become increasingly difficult as manufacturers shift their focus to digital technology. Originally scheduled for December 2025, the analogue switch-off has been extended by 13 months to January 2027.
It’s worth repeating that the PSTN switch-off date, in parallel with ISDN, is 31 January 2027. From that point on, out-of-date copper lines will be redundant. Their replacements are the fibre optic cables that have been widely rolled out in recent years, known as fibre to the premises (FTTP).
If you own a business, there’s no room for complacency on this score. Firms with PSTN landlines will have no alternative but to switch to VoIP. Even some ADSL broadband connections will require an upgrade to a full-fibre plan. Don’t leave this too late, as realistically, you could be looking at a visit from an engineer. Better still, consider arranging an audit with our team at Texaport.
Skipping an audit could lead to more significant problems than just accessing the phone or the internet. The PSTN switch-off could render payment terminals, door entry systems, faxes, ATMs, emergency telephones in lifts, CCTV, franking machines, and most alarms completely useless. Criminals may target businesses with compromised security systems.
The upside of all this is that UK companies that plan ahead will emerge stronger than before. PSTN and ISDN weren’t designed for an environment of apps, smartphones, the cloud and Microsoft Teams. VoIP systems, on the other hand, are ideally suited to our times. With Texaport’s expert-managed networks guidance, you can confidently discard outdated legacy systems and install the future-ready kit you need, making financial and efficiency gains to your business.
How will this affect you?
Ditching your landline phones shouldn’t feel like a sacrifice. You’ve almost certainly used Skype, a very commonly used version of telephony, or made video calls to your friends on WhatsApp or FaceTime, so you know how affordable and convenient the technology is. Some people harbour doubts – about security or choppy signals, for example – but VoIP has greatly advanced since its early days.
All in all, the advantages of switching over for a business are overwhelming. High-definition voice quality without the need for physical phone lines. The ability to make calls, including conference calls, away from the office on computers and mobile devices. The option to install extra lines (i.e., new numbers) as the business expands. Cheap or even free calls to the other side of the world.
At the same time, the specifics will vary from firm to firm. Broadly speaking, the scalability, flexibility and cost-effectiveness of VoIP can be a boon for small businesses, while larger enterprises will often have more complex needs to assess. Because their infrastructures will include a wide variety of technologies, an audit is essential for major companies like these. Doing nothing concrete and hoping for the best could, conceivably, lead to service interruptions that inflict not just a financial hit, but lasting reputational damage.
The myriad benefits of migrating to the cloud include call forwarding, blocking, voicemail, voice to email, call recording, hold music, caller ID, video, web conferencing, instant messaging, automatic call distribution, and interactive voice recognition. Whatever your company’s size, our team at Texaport will make that transition seamless.
Key switch-off dates
January 2027 might seem a long way off, but it’s vital to start planning now for a post-PSTN environment. If you put off the task of creating a step-by-step timeline or checklist to help you plan the changeover, you’re risking a last-minute rush or, worse still, disruptions to your services.
It’s entirely possible, remember, that companies who refuse to treat this issue urgently could find their payment machines and burglar alarms stop working all of a sudden. One survey found that 44.8% of UK businesses hadn’t even heard of the analogue switch-off, let alone PSTN switch-off dates.
An upgrade could take weeks or months for large organisations to organise effectively. The challenge is to meticulously audit existing systems and explore cloud-based alternatives in depth to secure the best outcome. The likelihood is that Microsoft Teams will play a prominent role in the company’s calls and video conferencing. Its low entry cost, clear video and voice quality, and cheaper international calls make it a sought-after collaboration tool.
Ready to move to the cloud?
Throughout this post, we’ve emphasised how important it is to futureproof your business in the weeks and months ahead. The effects of the PSTN switch-off on companies that don’t prepare for it could be grave. By contrast, those who take action now will be in a strong position going forward.
Our experts at Texaport can guide you through a seamless technological transition. Collaborating as trusted partners, we’ll determine the optimal path for your business so that when February 2027 comes around, you’re powering ahead and looking to the future with confidence. Don't let the PSTN switch-off disrupt your business, contact our expert team for details.
