The ISDN switch off

The end of an era for ISDN

Are you ready for change?

In 2015, BT announced it would be switching off its Public Switched Telephone Network (PSTN), including Integrated Services Digital Network (ISDN) services, by the end of 2025. It’s being referred to as the “PSTN switch off”.
Openreach, a business within BT which is responsible for the fibre, wires and cables which connect our country and keep us communicating, is running the withdrawal programme. Last year, it released its consultation about turning off the PSTN and allowed communications providers to respond and contribute.

What are ISDN and PSTN?

The Public Switch Telephone Network (PSTN) is the legacy analogue telephone network in the UK which allows us to make and receive voice calls.

Integrated Services Digital Network (ISDN) services were introduced in the 1980s and allow both voice and data to be combined and transferred over a single digital line, using the traditional PSTN network. According to Ofcom, more than two million UK businesses still use an ISDN connection.

Since then, technology has advanced and, thanks to the introduction of fibre optic services across the UK, many of the advantages of ISDN services have now been eradicated.


What does this mean to your business?

The PSTN network is being switched off in 2025 because, not only is it out of date, but the maintenance and running costs are no longer cost effective for both communications providers and business customers.

Instead of service providers and customers having a separate network for voice and for data, the changes mean both voice and data can be delivered on one single network.

When both the PSTN and ISDN networks are switched off, any remaining lines which are used solely for telephone calls will need to have been replaced with a technology which transfers calls over a data connection – these are known as IP voice or Voice over Internet Protocol (VoIP) solutions.

It’s important to note that any IP voice or VoIP service requires a suitable data connection, such as fibre broadband or Ethernet, to work effectively.