What is ISDN and PSTN?

PSTN stands for Public Switched Telephone Network. It’s the infrastructure behind the traditional telephone lines used in the UK. It is also used for card processing machines, fax machines and other technology. PSTN became the most reliable method of making voice calls and the main carrier for internet activity across the world.

ISDN stands for Integrated Services Digital Network (ISDN), allowing the digital transmission of voice and other services simultaneously, using the traditional PSTN network.

What is the PSTN switch-off?

Openreach has announced that in 2025 the PSTN networks will be switched off in favour of IP voice services, with a gradual phase out of older systems. That means fixed line services such as analogue or ISDN lines will no longer be available and Openreach will cease taking ISDN orders. It is now important that businesses make the switch to hosted telephony services to future-proof themselves.

Why is Openreach turning off the PSTN and withdrawing ISDN?

The PSTN was originally created in the 19th century and utilises legacy infrastructure that is aging and becoming more difficult to maintain. In short, these legacy systems are now deemed out of date. 

Over the last five years ISDN channels have declined in use by 30%. Subsequently, as of September 2023 businesses will no longer be able to install or add lines to existing ISDN or PSTN services. 

What will the replacement products be?

Voice over Internet Protocol (VoIP) solutions will replace traditional phone systems. For alternate data services, full fibre solutions and single order variants such as SOGEA and SOTAP will replace FTTC and ADSL connections.

When do I need to act?

As soon as possible. Various exchanges are already in stop-sell, which means businesses within those areas won’t be able to add or purchase any more lines onto a traditional telephony system. By 2025, every business will need to migrate to hosted VoIP and possibly upgrade their connectivity.

For more information about the PSTN switch-off or to talk to us about migrating your business over to hosted VoIP, please email us info@diamondsolutionsuk.com or call us on 0330 400 4455.