All About The BIG 2025 ISDN & PTSN SWITCH OFF And How We Can Help 

ISDN & PSTN switch off in 2025

The UK’s telecoms networks will undergo massive changes in three years as the telecoms network upgrade traditional phone lines in favour of internet-based systems.

In November 2017, Openreach announced it would not provide ISDN and PSTN services in the UK past December 2025 and all users would have to move to SIP (Session Initiation Protocol) and VoIP (Voice over Internet Protocol) solutions. And as a pre-cursor to this switch off, from September 2023, there will be a Stop Sell order, where you will no longer be able to order ISDN or PSTN products.

As of December 2025, all ISDN and PSTN services will be ceased. There will also be no maintenance available on any of these circuits.

What will be affected by the PSTN and ISDN switch off?

A range of services will be affected by the switch off, including

Phone lines and their numbers

ADSL and FTTC broadband internet services

Door–entry systems / CCTV

Burglar alarms / Fire alarms / Panic alarms

Fax machines

Emergency phones / Emergency lift lines

EPOS terminals

How can my business prepare for the ISDN & PSTN switch off and how DWD Telecoms can help

There are plenty of cheaper, faster, and more reliable alternatives for voice and data transmission.

To switch to IP-based services, such as a VoIP or SIP solution, might sound like there’s a lot involved and a hassle you can do without. Still, these changes will be of great benefit to your business. A business-grade hosted telephone service using VoIP revolutionises business communications. Advantages include reduced costs, excellent voice quality, flexibility, scalability and powerful functionality. Here at DWD Telecoms, we offer all the market leading solutions.

To get the correct service for your business, email our dedicated team at or call                01424 233333. Not only will we be able to assess your immediate needs, but we will also be able to offer you the scalability for your future requirements. Plus, we will be able to take all the hassle out of moving over to a new system, enabling you to keep your existing numbers and ensuring there is little to no impact on the day-to-day operation of your business.

If you are an existing customer, please don’t panic! If we haven’t already been in touch, we will be. We are busy working through our customers, upgrading and ensuring you are all good to go from 2025. If you want to speak to us sooner, do please get in touch at or call 01424 233333.

Useful Glossary


Integrated Service Digital Network was the first version of high-speed Internet. The service enables businesses to send data, such as voice calls or images, through their phone lines using the Internet


Private Branch Exchange (Telephone system)


Public Switched Telephone Network is what you might refer to as the traditional analogue telephone system – the system that enables landline connectivity. It generally consists of copper telephone lines, fibre optic cables, microwave transmission links, satellites, undersea telephone cables and mobile networks


Voice over Internet Protocol is a method of data transmission that allows for voice communications to be sent over the Internet


Session Initiation Protocol – The standard IP telephony signalling protocol used to start and terminate voice calls over the Internet

Hosted telephony           

An IP-based telephone system hosted in the cloud. It supports functionality such as transferring calls, call diversion, call waiting, call recording etc