ISDN Switch Off 2027 - Is Your Business Ready?

Switch to digital phone lines to avoid disruption.

What is the PSTN and Why is it Being Switched Off?

The PSTN or Public Switched Telephone Network has powered voice communication across the UK for over a century. It includes analogue landlines and ISDN services, all running over copper infrastructure.

But maintaining PSTN technology is increasingly unsustainable and incompatible with modern digital services. That’s why Openreach is transitioning the UK to a full-fibre and all-IP network.

From January 2027, services running on PSTN, including broadband, telephony, alarms, fax machines, EPOS systems, and lift lines will no longer function unless migrated to IP-based alternatives.

ISDN Switch Off How Does It Affect My Business

PSTN Switch Off Tips for SMEs

Migrate to VoIP and Digital Voice Services

Voice over IP (VoIP) is the leading replacement for PSTN-based phone lines. It’s more flexible, scalable, and cost-effective, especially for SMEs.
Your options include:

  • Hosted VoIP systems: Ideal for multi-site businesses or remote work
  • SIP trunks: Suitable for companies with existing PBX systems
  • Digital voice services: Basic landline replacement for smaller teams

Many VoIP solutions integrate with CRM, helpdesks, and collaboration tools to improve productivity.

Use the PSTN Switch Off as a Strategic Opportunity

Upgrading your analogue lines isn’t just about survival — it’s an opportunity to modernise.

  • Reduce overheads
  • Improve remote work readiness
  • Unlock better collaboration tools
  • Boost scalability and customer responsiveness

Life After the Switch Off

Organisations switching to a cloud-based system can save on costs as well as providing a range of extra features.
However, you will need to look at whether your existing internet connection is up to the job.

The benefits to your business of implementing the right data connection go beyond cost efficiencies and speedy web browsing. This increased speed, reliability and reduced latency enables you to take full advantage of bandwidth-intensive and real time applications in the cloud.

You need Ethernet solutions that provide dedicated internet access with guaranteed speeds and service level agreements that offer rapid response time – contact Gelle Telecom for your Business Broadband.

Futureproof Your Business Comms, simplify your systems, and stay competitive in a digital world - speak to Gelle Telecom

FAQ's...

Is the ISDN switch off and the PSTN switch off the same thing?

PSTN (Public Switched Telephone Network) switch-off: This refers to the complete retirement of the traditional copper-based telephone network in the UK. The PSTN is the legacy infrastructure that’s been used for decades to deliver landline voice calls and broadband services. It underpins both analogue and digital services, including ISDN.

ISDN (Integrated Services Digital Network) switch-off: ISDN is a digital service that runs on top of the PSTN. It’s used for voice and data services and was a popular solution for business telephony for many years. Because ISDN relies on the PSTN infrastructure, it is also being phased out as part of the overall PSTN switch-off.

The ISDN Switch Off isn’t just about your phones. There are plenty of systems – and acronyms – that are jostling for attention. For SMEs, the Switch Off affects phone lines, broadband connections, payment devices, door entry systems and much more.

Does your phone system rely on a digital phone line such as ISDN2, ISDN30 or PSTN Multiline? How about your broadband connection? Does it run on ADSL2, a standard for delivering internet connectivity through telephone connections?

Then there are your wider business systems and services to think about. Do you rely on a Single Analogue Exchange Line for Process Data Quickly (PDQ) handheld payment devices, franking machines, emergency alarms, lift lines, help point systems, door entry systems, fax machines or even care home alarms?

If you have any of these services linked to the ISDN, they will simply stop working. And that will place your business in a whole world of trouble.

If you have a PSTN or ISDN contract, you’ll need to switch over to an Internet Protocol (IP) telephony solution. There will be costs involved, but you’re also going to see plenty of benefits.

What’s more, most Voice over Internet Protocol (VoIP) phone packages work on a per-user pricing model, so you can save money in the long run by prioritising the connections you need.

You have a wide range of choices as well. If VoIP isn’t right for you, then take a look at Session Initiation Protocol (SIP) trunking; the digital method of making and receiving phone calls and other digital communications over an internet connection. This replacement technology can connect the majority of existing systems to the new public network. Then there’s Unified Communications (UC), hosted telephony and hosted contact centres.

For something as fundamental as connectivity, you want to make sure you have the right deal in place for your specific needs, so don’t focus on cost alone.

For the overwhelming majority of businesses, a ‘landline’ telephone number is still worth the investment.

Despite the proliferation of mobile phones, having a traditional landline phone number is still regarded as an indicator a business is real and trustworthy. A landline number gives the perception of an established, credible company. Even if you have it set to divert to your mobile, your customers won’t know.

Embracing the VoIP approach, to what we’d traditionally think of as landlines, offers much better call quality and options compared with mobile phones. Although many mobile phones now use Voice over Long-Term Evolution (VoLTE) and internet calling to improve reception, they don’t have the capacity to handle high call volumes.

As newer technologies develop and become more widely used, the role of the landline is not truly dying with the Switch Off of the copper lines, it’s just evolving. Rather than being the primary point of contact for your customers, it now sits within a larger range of communication options.

The good news is that you can keep your old PSTN phone number when you switch to digital voice services and full-fibre broadband. There could be a few exceptions around some ISDN special features, but in most cases, it will be a fast and easy process.

That means you won’t have to worry about losing touch with existing customers, or need to alter any of your marketing materials, print and digital collateral or vehicle livery.