Why the PSTN & ISDN Switch Off Matters

Why the PSTN & ISDN Switch Off Matters

2025 will be a significant year for UK telecommunications. It’s the year that British Telecom (BT) will stop the use of old analogue phone lines, turning off important lines of communication. Instead, all phone lines in the UK will operate digitally, following the mass acceleration and evolution of technology in recent years.

This change has been called "the Public Switched Telephone Network (PSTN) & Integrated Services Digital Network (ISDN) switch off", or more commonly, "ISDN switch off" and it’s relevant for all organisations who have direct contact customers in some way – particularly in the public sector.


Why is the PSTN and ISDN switch-off happening?

PSTN and ISDN are what are known as “traditional telephony” that operate using fixed lines. Many of the copper telephone lines that they run through have not been changed since the 19th century. As technology and broadband services have increased in reliability and quality at a faster rate, digital fibre networks present a far greater opportunity for improved communications UK-wide that are more cost-effective and easier to maintain.

In other words, digital telephony via fibre networks is the future-proof option because it doesn’t rely on one set location to work. The flexible nature of technology means if you have an internet connection, you can dial a number and connect with people wherever you or they are. Much of today’s modern technology integrates this idea of flexibility and accessibility at its core – the PSTN and ISDN switch off simply reflects this movement.


Why is it important?

BT's priorities have changed to support and develop a future of digital communications, and as a result their legacy infrastructure of fixed PSTN and ISDN telephone lines will cease to exist. In 2023, circuits related to PSTN and ISDN will no longer be available to purchase, and in December 2025 the PSTN and ISDN networks will close indefinitely.

The majority of UK organisations will be impacted by the PSTN and ISDN switch off; in 2020, 42% of SMEs stated they still used ISDN lines, compared to 33% amongst all UK organisations. It’s essential that organisations determine what current telephony structures they have in place which need to be changed. Inaction could lead to serious consequences.

How prepared is your organisation?


How can NFON support the change?

NFON are leading European operators of Cloud telephony. We deliver fast, quality, easy to manage voice communications operated by Voice over Internet Protocol (VoIP). Not only are we future-ready and digital-secure, but our technology is constantly improving. Migration to our services is simpler and as stress-free as you could imagine.


Find out more about NFON's work in the public sector to minimise the impact of the ISDN switch off

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