BT is switching off the UK's Public Switched Telephone Network. The process is already underway. The final deadline is now set for January 2027.
Most businesses have heard about this. Very few have done anything about it.
That is understandable. The switch-off has been announced and postponed enough times that it has acquired the quality of a distant deadline that never quite arrives. It will arrive. And when it does, the businesses that treated it as someone else's problem will discover that it is very much their own.
What actually runs over the analogue network
This is where most businesses get a shock.
The obvious casualty of the PSTN switch-off is the traditional telephone line. But the analogue network carries a great deal more than voice calls, and most of it is invisible in normal operations until it stops working.
Door entry systems connected to telephone lines will stop working. Lift emergency phones, which are legally required to connect to a live line, will fail. Fire alarm monitoring systems that send alerts over analogue lines will be unable to make contact. Burglar alarm autodiallers will be unable to dial out. Fax machines will become inoperable. PDQ and card payment terminals that use analogue lines rather than IP connections will stop processing.
Most businesses have at least one of these. Almost none have a complete picture of which of their systems depend on the analogue network.
The ISDN question
ISDN (Integrated Services Digital Network) is also being retired. ISDN has been the backbone of business telephony in the UK for decades.
The businesses most at risk are those running older PBX phone systems specified for ISDN. These systems will not work on the replacement technology without significant modification or replacement. The cost and disruption of doing this at short notice, under deadline pressure, with a queue of other businesses in the same situation, will be substantially higher than doing it now in an orderly way.
What is the replacement technology?
Voice over IP (VoIP) and hosted voice are the primary replacements for traditional PSTN and ISDN telephony. Calls are made and received over the internet using the same connectivity that carries everything else.
For most businesses, hosted voice is a better, cheaper, and more flexible solution than what it replaces. Calls cost less. The system is managed in the cloud. Users can make and receive calls on any device, from any location. Features that cost extra on a traditional system are typically included.
The transition does, however, require that the internet connection is up to the task. A business running VoIP over an inadequate broadband connection will experience poor call quality.
The timeline that is not going to change this time
January 2027 is the Openreach deadline. But the practical timeline is shorter, because installation capacity is not unlimited. The businesses that leave this until late 2026 will be competing for engineer availability and supplier resources with every other business that also left it until late 2026.
The businesses that act now will have their choice of timing, their choice of supplier, a managed transition, and the ability to deal with any unexpected complications before they become urgent.
IT Works manages analogue switch-off migrations for businesses across the UK, from initial audit through to full telephony and connectivity transition. If you are not certain what services in your business depend on the analogue network, that audit is the right place to start.
IT Works switch-off readiness review:
enquiries@it-works.co.uk | 0121 270 0808 | it-works.co.uk/isdn-switch-off