The ISDN Switch off
Learn about BT's ISDN switch off and what it means for you
In 2025, all legacy phone lines (the PSTN & ISDN network) will be switched off.
It was announced by BT that the copper based PSTN and ISDN network began decommissioning from 2020 – with the aim of turning the network off entirely by 2025.
The PSTN (Public Switched Technology Network) is the traditional, copper wire based telephone network which has remained pretty much unchanged since the early days of public telephone networks.
Why is ISDN and PSTN being switched off?
The short answer is that they are older technologies that are more expensive for BT to maintain. PSTN is the traditional telephone line network which carries analogue voice data over copper lines.
As of 2023 BT will no longer accept any new orders or amendments to services applicable to any existing ISDN products, and although 2025 can still seem a long time away, the looming freeze on amendments to existing circuits next year certainly isn’t. We’ve all seen the dramatic changes in technology over the past few years, especially recently. It’s all around us: smartphones, apps, the cloud, Internet of Things and so on.
What you probably don’t notice is the infrastructure that makes everything work. The telephone lines strung across the streets, the web of copper cables buried beneath your feet, some of which have been down there since the 19th century. Essentially, much of this infrastructure needs to be upgraded.
What systems will be impacted by the change?
Many things are going to change with the ISDN and PSTN switch off. It’s not just your phone services you need to think about. Everything that currently uses the old phone network, all your non-voice services connected to PSTN or ISDN lines will be impacted. For example:
- Alarms
- EPOS machines
- Door entry systems
- CCTV
- Fax machines
If you currently use any of these systems in your business, check to see if they will be impacted by the change, or give Yoozoom a call and we'll check for you.
What technology is replacing ISDN and PSTN?
The BT ISDN and PSTN switch off marks the next evolution of telecommunications technology. It is being replaced with a technology called SIP trunking. In short, this technology allows you to make and receive calls over the internet. The terms you'll probably hear that describe this include IP Telephony, IP Phone Systems or Cloud Phone Systems.
What are the benefits of cloud phone systems?
There are a host of benefits to upgrading to an IP Phone system. For example, being able to have employees work remotely, enjoy free calls, chat or video between users and improved agility are just a couple of the benefits associated with cloud based technologies.
To learn more about the benefits of upgrading your telephone system, get in touch or learn more about our cloud only phone systems by clicking here.
ISDN Switch Off Timeline
2018
The announcement of the closure of the ISDN and PSTN networks in 2025 goes public.
2020
Salisbury becomes the first UK town where ISDN and PSTN lines are no longer available for purchase.
2021 (May)
As the trial expands, Mildenhall follows Salisbury - no new ISDN and PSTN lines are available.
2021(December)
An additional 117 exchanges are upgraded to faster FTTP (full fibre) connectivity, and no new PSTN and ISDN lines are available within their footprint.
2022
In Salisbury and Mildenhall, WLR (Wholesale Line Rental - including PSTN and ISDN) is withdrawn entirely.
2023
WLR (including PSTN and ISDN) is no longer sold in the UK.
2025 (December)
WLR is withdrawn nationally, with all voice calls now over IP voice services.
Speak to an expert to discuss your phone system upgrade.
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The ISDN and PSTN network will be switched off in:
