The BT Openreach 2025 ISDN & PSTN Switch Off

In 2015, BT Openreach announced plans to permanently switch off their ageing PSTN and ISDN networks by December 2025. It brings an end to analogue phone lines and moves communication technology into an entirely online space. 

This marks the biggest change in the telecoms industry for over thirty years, but what does it mean for you? 

These changes will have knock-on effects for many businesses, particularly those who still rely on fax machines or landline phones who will have to find alternative communication methods. But, by being keen to adapt and taking action sooner rather than later, you can minimise disruption to your business.

We’ve put together answers to some of the most frequently asked questions below. If you need more information or guidance, feel free to get in touch with us today and we will happily help you to prepare your business for the fast-approaching deadline.

Contact us and we will help prepare your business for the fast approaching deadline.


What is the switch off? And why is it happening?

At the end of December 2025, traditional telephony – including ISDN and PSTN – will be switched off and withdrawn from service. This means that traditional services cease to exist. 

The priority for Openreach moving forward is to maintain a readily available fibre-first network. But, as a result, their legacy infrastructure and equipment serving the PSTN is now ageing, becoming more difficult to maintain, and holding them back.

The BT Openreach PSTN and ISDN 2025 Switch Off Timeline

What are ISDN and PSTN?

ISDN stands for Integrated Service Digital Network and evolved from dial-up, using hard-wire phone line connections to allow communication. ISDN is available in two common variants: ISDN2 supports channels in pairs, with between 2 and 8 ISDN channels. ISDN30 is usually used by larger businesses, with options to have between 8 and 30 ISDN channels on each service. On the other hand, PSTN (Public Switch Phone Network) is the classic analogue phone system, enabling landline, broadband, and alarm line connectivity using transmission through copper wires


What other lines and call services are impacted by the 2025 closure?

All copper wire services will be affected by the closure. This includes all broadband services (excluding FTTP or leased lines) and any alarm monitoring, including Redcare, that you have on-site. Telephone systems and home landlines will also be affected. All calls will have to be made on a VoIP handset or telephone system.


Will Openreach provide the PSTN replacement products and services?

Moving forward, Openreach will provide new data-only broadband products. These will replace the traditional broadband (based on PSTN service) and are referred to as Single Order Broadband which consists of:

  • FTTP

Single Order GEA (SOGEA) and SOGFAST are new broadband packages which use the same technology as GEA FTTC (Fibre-to-the-Cabinet VDSL or GFAST (for ultrafast speeds)) with the exception that it doesn’t share the line with a WLR service (the PSTN network isn’t enabled for the line). SOGEA and SOGFAST offer the same data rates, performance, and VDSL technology as FTTC and GFAST, is available in the same geographic areas as FTTC/GFAST, and with the additional benefit of being a true all IP solution broadband service to meet the demands and reliance for today’s and future connectivity solutions.

These new broadband services will require you to invest in new equipment. We can advise you on the best solution for your business, so please contact us to discuss your options. 


Will new fibre products be more expensive than WLR?

This is a key concern of many providers and users. Before the switch, consumers could rent a line for making and receiving calls for as little as £10 to £15, whereas a full Fibre to the Premise (FTTP) service can begin at around £50 per month. 

Arguably, this is a significant increase for those just wanting voice on their lines. For customers who do just want voice on their lines, and have no requirement for broadband, then a low bandwidth variant is expected, but there is little information that has been published about this to date.


What will happen to alarm lines, payment terminals, and other special line rental services after 2025?

During the PSTN closure, all these services will need to be tested with new internet protocol (IP) technology and the single order products. 

This means alarm line companies, payment terminals, traffic light systems, payphone lines, emergency pendants, dialysis machines, telemetry devices, and any other special service must be tested by the equipment manufacturers. 

Openreach can provide line test facilities for testing equipment against their individual line configurations.


What does the 2023 stop sell date mean?

From September 2023, Openreach will issue a full “Stop Sell” of new supply of traditional lines. 

As part of the nationwide PSTN and ISDN withdrawal, from the end of September 2023 there will be no new line installations for either PSTN or ISDN, increase of ISDN channels, change of address, restart of a stopped line, or working line take over. 

Line transfers will be accepted providing there is no change to the installation when the line moves from one provider to another. All calling and network features, such as caller display, presentation number and features to prevent nuisance calls such as anonymous call rejection, will be allowed with the exception of two trial exchanges in their Salisbury and Mildenhall exchanges.


Is December 2025 a strict deadline?

Openreach is adamant the December 2025 deadline will be met. PSTN lines that have not migrated to alternative services by April 2025 will be deemed orphaned assets and Openreach intends to work with communication providers to identify and migrate these customers to alternative products by the December 2025 deadline.

The actions to be taken in this case are yet to be defined. And the difficulties identifying the use of the line, and in some cases the end-user customer, along with the contractual agreement to move, is still to be confirmed. But be assured, services will be withdrawn and customers will be impacted should they not move in time.