What is the PSTN switch-off?
BT is switching off the Public Switched Telephone Network — the traditional copper telephone infrastructure that has carried UK phone calls for over a century — by January 2027. Every business using an ISDN line, a traditional PBX, an analogue fax machine, or any service that relies on the old network will be affected.
This is not a rumour or a distant threat. It is a confirmed, scheduled event. And January 2027 is closer than many business owners realise.
Who is affected?
The short answer is: almost every business in the UK. Specifically, you are affected if you currently use any of the following:
- ISDN2 or ISDN30 lines for your phone system
- An on-premise PBX that uses ISDN trunks
- Analogue phone lines for fax, alarms, payment terminals or door entry
- Any service that BT or your telecoms provider has told you connects via the PSTN
What are the options?
There are three main migration paths, depending on your current setup and future requirements:
SIP trunking replaces your ISDN lines with internet-based calling, while keeping your existing PBX hardware in place. This is the lowest-disruption option if you have recently invested in a PBX.
Hosted PBX / cloud voice replaces both the lines and the on-premise PBX with a fully cloud-hosted phone system. This typically delivers better features, lower cost and greater flexibility — particularly for hybrid and remote working.
UCaaS (Unified Communications as a Service) goes further, integrating voice with video, messaging, file sharing and collaboration into a single cloud platform — Microsoft Teams Phone, for example, or a dedicated UCaaS solution.
Why act now rather than wait?
Migration takes time. The survey, design, procurement, installation and testing of a voice transformation project typically takes 8-16 weeks. With multiple UK businesses all facing the same deadline, demand for migration services will increase significantly as 2027 approaches — meaning longer lead times, potentially higher costs, and less choice of provider.
Businesses that act now can choose the right solution at their own pace, negotiate better commercial terms and avoid the disruption of a rushed migration.
How Open Way Technologies can help
Open Way Technologies provides independent advice on voice transformation — at no cost to you. We assess your current setup, understand your requirements and introduce you to the right provider from our network. Contact us today.