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Are you ready for the PSTN and ISDN switch off?


In 2015, BT Openreach announced the end of PSTN and ISDN support, and began shutting down UK networks in 2020.

If your business still relies on legacy landline communications, you must upgrade prior to the full switch off in 2025. 

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.
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onwards, the mass IP network migration will begin, with VoIP (voice over internet protocol) core networks replacing the outdated legacy telephony.




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:


Download Checklist

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.

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.


Benefits you’ll experience with RingCentral

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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.

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.

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Disaster Recovery
Where your internet connection fails, RingCentral provides an automatic failover capability to ensure you don’t miss a call.


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.


Speak to a specialist today to learn more about preparing for the PSTN and ISDN switch off with RingCentral


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