Everything you need to know about the UK PSTN Switch Off


What is it and how will it impact your business?

ISDN and PSTN network shutdowns began in 2020, making it more important than ever for UK businesses to future-proof. The UK telecoms industry has been closing its PSTN networks, undergoing a transition to all-VoIP networks. This move has been driven by telecoms operators who are concerned about the rising costs of maintaining legacy PSTN equipment.

The all-VoIP option offers a simpler and more cost-effective solution, but it could result in a period of transformation that all businesses should be aware of.

Here’s everything you need to know about the PSTN/ISDN shutdown.

What is the 2025 network switch-off?

ISDN, or Integrated Service Digital Network, is the first iteration of high-speed internet, first appearing in the 90s. It revolutionised internet connectivity in its day and is widely considered to be the foundation for modern internet solutions.   

Meanwhile, the Public Switch Phone Network, or PSTN, is the system that enables landline connectivity. Having been around since the 1800s, it allows for information to be transmitted through a network of copper wires. The fact that PSTN is still the foundation of communication for millions in the UK shows why some are concerned that the switch-off could lead to continuity issues for businesses.

Since 2020, businesses have not been able to purchase ISDN and PSTN circuits in the UK. By 2025, the PSTN circuits will be shut off completely, marking a major step towards the UK’s mass IP-network migration. Voice over Internet Protocol (VoIP) core networks is set to replace all outdated legacy technology during this time. This includes ISDN and PSTN.

Why are providers migrating everyone to VoIP?

So with potential continuity issues on the horizon, why is the switch-off necessary? In the long term, the switch-off will help telecoms save significant costs by not having to support legacy technologies. Switching to all VoIP allows telecom providers to only maintain one network – a much cheaper option.

Who will be impacted?

BT estimates that more than 2 million local UK businesses will be impacted by the switch off, particularly those who rely on the use of fax machines and landline telephones. Any business that currently operates on ISDN or PSTN will be impacted, which equates to around 2.4 million businesses in the UK, including 42% of SMEs and 33% of larger firms.

What should you do now?

Telecom operators are instructing businesses to consider VoIP as a method of data transmission. This allows for voice messages and images to be sent over the internet using your current hardware, using an adaptor device.

For more advice on your business’s communications, contact us at Consultiv here.