6 Steps To Prepare for the PSTN Switch-Off

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BT Openreach announced the end of PSTN and ISDN in 2015 and began shutting down UK networks in 2020. But with many major events taking precedence, the PSTN and ISDN network switch-off has had little airtime.

To shine a light on matters, we’ve put together a rundown of what it all means, why it’s happening and how you can prepare.

What is the 2025 PSTN switch-off? 

The big telephony switch-off of 2025 is an initiative driven by telecom operators to save the expense of maintaining a legacy, increasingly obsolete telephone network. While often referred to as the PSTN switch-off, the digitisation project refers to the switch-off of both PSTN and ISDN networks, but what exactly are these, and how do we use them?

What is ISDN?

Integrated service digital network (ISDN) is the first iteration, launched years ago, of high-speed internet. ISDN first appeared in the 90s and revolutionised internet connectivity. Many credit the technology as being the groundwork for modern, faster internet solutions.

What is PSTN?

PSTN stands for Public Switched Telephone Network. This traditional analogue phone network supports telephone communication via landline connectivity. The network, introduced in the 1800s, consists of copper wires transmitting information, predominantly phone calls and fax messages.

Instead of using this type of telephony, businesses are encouraged to transition to an all-VoIP network, meaning our phone calls and communication will take place solely via the internet.

As of 2025, no one will be able to purchase integrated services digital network (ISDN) or public switched telephone network (PSTN) circuits in the UK. Between April and December 2025, there will be a forced migration, and businesses are encouraged to explore alternatives ahead of time. From 2025 onwards, the mass IP network migration will begin, with VoIP (voice over internet protocol) core networks replacing the outdated legacy telephony.

Young woman talking on smart phone at home office. This type of phone will help businesses prepare for the PSTN switch-off

Why is the PSTN switch-off happening?

The current network is old and tricky to maintain. What’s more, the PSTN can’t meet the demands of modern communications. By switching to all-VoIP, telecom providers only have to maintain one network, which is much cheaper.

What stage is the PSTN switch-off at now?

In the UK, the switch-off is currently underway and scheduled to be completed by December 2025. The next milestone is the stop sell of new wholesale line rental (WLR) across the UK in September 2023. This means there will be no new line installations for both WLR and ISDN, including conversions of the WLR Line to an ISDN Line, an increase of ISDN channels, a change of address, start of a stopped line, or working line takeover. 

Diagram showing a timeline of the PSTN switch-off

How will the PSTN switch-off impact businesses?

The UK 2025 switch-off will impact all businesses currently operating on ISDN or PSTN. The biggest impact will be felt by those with heavy use of fax machines or landline telephones.

There are other implications beyond phone services with other devices that connect to PSTN, such as alarms, door entry systems, CCTV and electronic point of sale (EPOS) systems. The thing is, many businesses are still using legacy systems and the devices mentioned, so there will likely be shockwaves unless changes start to happen soon. Here are some stats to highlight the point:

Insights on legacy system usage


[See sources here: 70%, 2.4 million.]

What if you wait to prepare for the PSTN switch-off?

In short, you shouldn’t wait it out. If you’re still using ISDN/PSTN lines or legacy telephone systems, this is a nudge for you to review your business communications infrastructure. Telecom operators advise customers to explore alternative options to legacy systems now or face challenges if they wait until 2025 when demand for VoIP services will be high. Waiting it out could also mean you risk being unprepared for the switchover and impacting your business continuity in the process.

What are your options to get ready for the PSTN switch-off?

Most businesses will be steered toward VoIP, a method of data transmission that allows for voice messages, images and files to be sent via the internet. Using VoIP telephony means your business devices and your team can send information, including files, images and fax, and make calls through their internet connection instead of via the old networks fast becoming obsolete. When switching to VoIP, businesses can use an adaptor device to turn their landline-reliant phones into hardware with internet connectivity.

What are the benefits of VoIP?

40% of the UK market has already recognised that switching to a VoIP solution provides several key benefits. VoIP technology is much more flexible than legacy systems and allows business teams the freedom to collaborate using different devices, from anywhere with WiFi, using the same business number.

What’s more, you’ll have a much more cost-effective system with manageable monthly fees for the most part, rather than a huge capital investment as with traditional PBX systems. In fact, RingCentral cloud PBX customers, for example, save on average 42% on their monthly phone bills, with some saving as much as 70% when they switch from ISDN and PSTN lines.

Here’s a quick summary of the benefits you’ll experience with RingCentral:

  1. Easy to buy, easy to set up: Auto-provisioning of VoIP telephones allows for quick installation with no capital expenditure, and with converged voice and data, there are no line rental costs.
  2. Flexibility and Scalability: Your phone number isn’t tied to a physical location, which allows you global access to your number over the internet. Internet-based phone systems also have no user limits. Geographic and international numbers can be redirected to your VoIP phone or softphone, meaning one phone with countless numbers.
  3. Disaster Recovery: Where your internet connection fails, RingCentral provides an automatic failover capability to ensure you don’t miss a call.

A snapshot of even more benefits:

  1. Significant cost savings
  2. Avoid system failures/outages
  3. Avoid having your manufacturer end support of an old phone system
  4. Improved experience for your customers
  5. Increased productivity and collaboration
  6. Evolve the flexibility and mobility of your business communications
  7. Simplify security with one solution that is continuously up-to-date
  8. Enable unmatched collaboration across meetings, projects and critical customer interactions

Now read the ultimate guide to what VoIP is and its benefits

6 steps to prepare for the PSTN switch-off

It would help if you took some time to ensure your business is ready for the switch-off. If you haven’t started preparing for the PSTN switch-off yet, here’s our checklist to help you keep on top of things:

1. Check your devices

It’s important to check if any other devices run off your PSTN phone lines. You may not even realise that certain systems could be relying on your traditional phone lines to function. For example, lift emergency lines, cash machines, payment terminals, panic alarms and door entry systems could run via your PSTN lines. In this case, you’ll need to switch these devices to an IP mode if it has one available or speak to a special services provider to upgrade.

2. Review your connectivity

You’ll need to ensure your internet connection is up to the task. If you haven’t got a strong broadband connection, you’ll need to start looking to upgrade to low-latency high-bandwidth connectivity to give you the resilience you need. This will allow you to support the quality of voice calls and HD video conferencing that have become essential in everyday collaboration.

3. Think about your hardware

Taking stock of how your business uses hardware and how this might change with a more digital infrastructure is important. You might want to ease off your reliance on bulky hardware and embrace softphones and more mobile software alternatives to aid your team’s agility and flexibility.

4. Select your solution

Now you’ve followed steps one to three; the time has come to pick your solution. Which is going to be best for your business? The answer is whichever is better for your needs. You will need to look into how you currently use your phone system and how you plan to use it in the future. On top of this, you’ll need to assess the benefits and drawbacks of potential solutions.

5. Involve your employees

As with many business changes, training is crucial. However, encouraging your employees to be genuinely interested in your solution is also vital. But how can you make a phone system seem exciting? At the end of the day, the whole point of technological advances, like VoIP telephony, is to not only make aspects of business easier but better. Ensure you know everything there is to know about your solution. Your provider may be able to provide training and enablement forums to show you and your team all there is to know.

Once you have all the info you need, arrange a team meeting to run through the new phone system with employees.

6. Embrace the change

Seeing the PSTN switch-off as an opportunity rather than an inconvenience is important. Digital transformation is a top priority for many businesses now, and this transition opens doors for innovation.

The bottom line

Preparing will help you avoid getting caught out in the months leading up to the switch-off. Whether you need to enable hybrid or remote work for the long term, expand and future-proof your business, or remain operational in the face of the switch-off, it’s crucial to act now.

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Reach out to have a chat about how to prepare for the switch-off

Originally published Nov 15, 2020, updated Nov 27, 2023


    Severine Hierso is a Director of Product Marketing at RingCentral, the leader in cloud communications solutions, and is passionate about creating value, differentiation and messaging, ensuring a better experience for customers and partners.

    She has gained extensive international product marketing, market research, sales enablement and business development experience across SaaS, telecommunications, video conferencing and technology sectors within companies such as Sony, Cisco, Cogeco Peer 1 and Dimension Data/NTT.

    Severine holds a Master’s degree in economics and her hobbies include long distance runs and travelling.

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