Legacy connectivity technologies, particularly the PSTN and ISDN, have been the foundation of many organisations' communications for some years now, but have increasingly shown their limitations, with aging copper networking increasingly prone to faults and unable to maintaining the resilience and availability that modern voice, email, and video platforms demand. Indeed, PSTN incidents rose by 45% in 2024 alone, with 192 million hours of service lost between 2024 and 2025 - all of which had a serious financial, operational, and reputational impact on the organisations affected1.
In light of this shift, a full switch-off of the PSTN network has been in progress for several years now, and will be concluded by January 2027, after which any organisations that have not migrated to alternative systems will be without voice and broadband services.
Fortunately, all-IP connections offer considerable advantages over these legacy technologies, and so this change represents an ideal opportunity to optimise and futureproof the performance and availability of your voice and broadband services.
What is the PSTN switch-off?
In 2018, BT Openreach announced the long-term plan to transition the whole of the UK from PSTN to IP for all voice calls. To this end, as of September 2023, no new PSTN or ISDN lines will be deployed, in preparation for 2027, when the remaining ones would be permanently switched off. At the time of writing, a stop-sell has been placed on multiple voice products built on these services, meaning existing ones will initially remain in place, but new ones will be withdrawn from sale.
For organisations planning to transfer to new solutions before stop-sells are implemented in their active regions, it is important to be aware that not all services will necessarily be available. For example, in regions where the FTTP priority exchange is in place and FTTP is available at premise level, this is the only service that they will be able to utilise. Outside of these regions, other transitional solutions, such as SoGEA and SoADSL - may be available. All this must be factored into organisations' migration plans.
Why are numerous organisations already embracing IP-based connectivity?
IP technology allows broadband connectivity and compatible digital voice services to operate over the same data network, removing the need for legacy PSTN connectivity. These services can be delivered over a broadband connection, such as FTTP, SoADSL or SoGEA, or over an ethernet service (although the underlying connection does not provide a traditional dial tone as standard).
This will open up a whole new era of quality and resilience in the way voice and broadband services are delivered across the country, provided organisations are aware of the impending change and plan accordingly. This will involve working closely with a trusted connectivity partner to not only migrate to a new service, but ensure the solution chosen will provide the required performance, resilience, and scalability, while retaining cost control.
IP technology allows broadband connectivity and compatible digital voice services to operate over the same data network, removing the need for legacy PSTN connectivity. These services can be delivered over a broadband connection, such as FTTP, SoADSL or SoGEA, or over an Ethernet service. However, the underlying connection does not provide a traditional dial tone as standard.
How Exponential-e can help
Exponential-e is already working closely with organisations across multiple sectors to prepare for the switch-off, providing them with a range of migration options that will not only ensure disruption is minimised, but open up new opportunities to reduce costs, while optimising resilience and service quality.
There are a range of ways these benefits can be unlocked, depending on where you, your teams, and your customers are active, the services you utilise each day, and whether you currently utilise copper wiring for other services. It is important to bear in mind that not every available solution will necessarily be the right fit for every organisation, but our teams are here to guide you.
Exponential-e's portfolio of services - including, FTTP, SoGEA, SoADSL, and VoIP services - was designed to be truly vendor-agnostic for precisely this reason. We work with multiple carriers to ensure our customers and their end users enjoy the best possible coverage across the entire UK. As with every aspect of our services, our approach is a consultative one, with our own experts working closely with customers' teams to develop a robust migration plan to mitigate the impact of the switch-off and ensure a smooth transition to your ideal IP-based service.
Do not hesitate to contact us to discuss your voice and connectivity requirements and how the impending switch-off will affect you.
Frequently Asked Questions
What is the PSTN switch-off?
The PSTN switch-off is the UK's nationwide retirement of the Public Switched Telephone Network (PSTN) and ISDN services. By January 2027, all organisations will need to use IP-based voice and broadband services instead of legacy copper telephone lines.
When is the PSTN switch-off?
The UK PSTN network will be permanently switched off in January 2027. Organisations that have not migrated to IP-based connectivity before this deadline risk losing access to traditional voice and broadband services.
Will my business phones stop working after the switch-off?
If your organisation still relies on PSTN or ISDN services without migrating to an IP-based solution, traditional business phone services may no longer function once the network is switched off.
What technologies will replace PSTN?
Modern alternatives include FTTP, Ethernet, SoGEA, SoADSL, VoIP and Cloud-based communications. These services provide greater resilience, improved call quality, scalability and support for hybrid working.
What are the benefits of migrating before January 2027?
Migrating early helps avoid service disruption, improves business resilience, enhances voice quality, reduces operational costs and provides sufficient time to test and optimise your new connectivity before the deadline.
Will I need full fibre broadband?
Not necessarily. While FTTP provides the highest performance where available, organisations may also benefit from SoGEA, SoADSL or dedicated Ethernet services depending on their location, infrastructure and business requirements.
What other business services could be affected by the PSTN switch-off?
Many legacy services rely on PSTN connections, including lift emergency phones, alarm systems, payment terminals, telemetry devices and some building management systems. These should all be assessed as part of your migration planning.
How can Exponential-e help with the PSTN migration?
Exponential-e provides a consultative, vendor-agnostic approach to migration, offering FTTP, SoGEA, SoADSL, Ethernet and VoIP solutions through multiple UK carriers. Our experts work with your organisation to create a tailored migration strategy that minimises disruption while improving resilience, scalability and long-term performance.
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