The PSTN/ISDN Switch Off

November 17, 2022

In 2015, BT announced it will be switching off the PSTN and ISDN in 2025, marking the biggest change in the telecoms industry for over 30 years, but what does the end of PSTN and ISDN mean?

What is ISDN and PSTN?

The Public Switched Telephone Network (PSTN) is the landline telephone system originally set up for analogue voice communication. It works by sending analogue voice data over a circuit-switched phone line made of copper wires. Before digital transmission was available PSTN was the most reliable method of making voice calls and the main carrier for internet activity across the world.

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

What is the PSTN and ISDN Switch Off?

BT released a statement in 2015 that it would stop taking new ISDN orders in 2020, with a view to switching-off and deactivating its ISDN network completely at the end of December 2025. They will be transferring their networks from analogue and digital to an IP network.

ISDN and PSTN are being replaced because they are now outdated systems that take too much time and money to keep running. By converging all services – voice, data, video, and broadcasting to the IP protocol, BT only has to maintain one network, not several.

What other lines and calls services are impacted by the 2025 closure?

The PSTN supports a number of Openreach products: In technical acronyms these are known as WLR3 analogue, ISDN2, ISDN30, LLU SMPF, SLU SMPF, Narrowband Line Share and Classic products. These products are generically referred to, as WLR (Wholesale Line Rental) products. When the analogue network closes in 2025 these products will no longer be available.

How and when will Openreach start withdrawing service?

Openreach will stop selling WLR products that are reliant on the PSTN from September 2023. They will then completely close the WLR platform December 2025. After this date WLR products will no longer be available.

As a Kings Secure Technologies customer, what does this mean to me?

With the end of PSTN and ISDN services approaching, it is our intention to stop selling PSTN devices such as Digi comms and Dualcom/any alternative device using a PSTN path by 31st March 2022. As a customer who has an existing monitored alarm with the Kings Secure Technologies group of companies, we advise you to check if PSTN services are available on your line for any planned service provider change (note: PSTN is being removed from new or existing line changes by some providers). If you are using a signalling device connected to a PSTN line, please contact your KST Account Manager or email to discuss suitable signalling options that do not use PSTN in preparation of the 2025 deadline.


What our Customers say

We wanted a smart-looking, contactless approach to access control here at Little Dot. We love the Openpath solution proposed by KST; it’s sleek, simple to use and has excellent reporting features. What’s more, KST’s inhouse commissioning team remotely configured the software to meet our requirements - including who goes where and when, through which doors, the reporting we need and integration to our fire alarm system. Thanks to this we have saved the cost of two days labour on install!

Greg Rochford
IT Manager - Little Dot Studios

KST has once again exceeded all expectations with their outstanding service. Safety is our number one priority for both our Post Masters and customers, therefore we are always on the lookout for new technologies and new ideas. Morphean platforms, along with the installation and maintenance provided by KST, has been the perfect decision for us due to our existing knowledge of their excellent services and competitive prices.

Mark Dinsdale
Security Programme Manager - Post Office Ltd

The mobilisation was smooth with little involvement required from ourselves. Communication, in particular, has been extremely strong with regular meetings. Monthly management information has been circulated and Clipper are using the real time management information that KST have provided with their DYMENSiON software. We also have working action plans on each site focusing on improvements and change management. All in all I would be happy to recommend KST to any company looking at contract award; our experience has been very positive and I am happy to endorse them.

John Welsh
Head of Bonded & Secure Operations - Clipper

The whole process of mobilisation and onboarding to KST was conducted in an exceptional manner, from start to finish. The preparation for the move between City Plumbing Supplies and KST was comprehensive. Collaboration was very good. The days of transfer were event free and smooth - with no major issues. The branches’ onboarding onto the KST system during the 12 weeks following the mobilisation was completed fully with excellent communication sessions conducted on a weekly basis. We are now looking forward to a long and effective partnership with KST.

Steve Kemp
Security, Audit & Loss Prevention Manager - City Plumbing Supplies

We’ve been delighted with the partnership between ISS and KST and the approach to transferring the access control contract. The teams have gelled quickly to understand our estate and we’ve seen significant service improvements.

Andy Southern
Head of Security - Santander Bank