The BT Switch Off

Jul 10, 2023 | Insights, News

Is your business ready for the Big BT Switch Off?

The UK is phasing out the PSTN (Public Switched Telephone Network) and the ISDN (Integrated Services Digital Network). These networks were always the traditional way telephony and broadband services we supplied to companies until recently.

Both networks are old and costly to maintain. The old copper wire telephone network was first established in 1876, so have been around for a while now and is defiantly in need of an update!

What will replace these old networks?

PSTN and ISDN lines used for voice are being replaced by using a technology called VoIP. 

VoIP (Voice over Internet Protocol) has been adopted as a direct replacement for the old-fashioned PSTN or ISDN phone line & telephone system.

In its most simple term, the system takes voice signals, converts them into digital signals (Voice packets) and then sends them over the internet, where the voice signals are reassembled at the other end. The process is instantaneous, and the result is a crystal-clear HD call.

Companies using telephone lines for other services, for example, Fax, Franking machines, PDQ machines and Alarm lines, will also need to arrange IP or Mobile alternatives.

Some broadband services will also be affected. Broadband services which are currently being delivered by PSTN lines will also be affected and will need to be either upgraded to SoGEA (Single Order Generic Ethernet Access) or FTTP (Fibre to The Premises). These new broadband connectivity services do not rely on a traditional PSTN line to work.

When is this happening?

BT has announced that the switch-off will complete in 2025. By this date, all services which currently rely on the PSTN or ISDN networks will need to have moved over to the IP. 

The project is now well underway. Back in 2020, the first ‘Stop Sell’ stages started to be implemented in certain areas. This meant new ISDN services were made end-of-life. 

The next milestone is September 2023, when the whole of the UK will also go into the ‘Stop Sell’ stage of the BT switch-off, so all the legacy services will be unavailable to order or change. 

This is why we are encouraging our customers to move to the new replacement services such as VoIP, SoGEA and FTTP now.

Please contact us if you have any concerns or need any advice regarding the important changes in the industry. We are here to help!

PSTN Switch Off and Landline Replacement Timeline


November 2017

BT Openreach announce it’s intention to switch off the PSTN in 2025.

December 2020

Customers in Salisbury cannot purchase new ISDN lines or add new features

October 2021

Customers across 169 locations cannot purchase new ISDN lines or add new features

April 2023

Customers using the PSTN network in Salisbury and Mildenhall will have reduced service leading to complete cease of services

September 2023

Customers across the whole country cannot purchase new ISDN lines or add new features

December 2025

The PSTN network is completely switched off across the UK

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