The BIG BT ISDN & PTSN SWITCH OFF and what it means for your business

The BIG BT ISDN & PTSN SWITCH OFF and what it means for your business

How will your business be affected by the BIG BT ISDN & PTSN SWITCH OFF? And what to do about it!

BT’s ISDN & PSTN switch off in 2025

The UK’s telecoms networks will undergo massive changes in the next three years, with BT shutting off its traditional phone lines in favour of internet-based systems.

In November 2017 BT announced it would not provide ISDN and PSTN services in the UK past December 2025 and would be moving all its business customers to SIP (Session Initiation Protocol) and VoIP (Voice over Internet Protocol) solutions. And, as a pre-cursor to this switch off, from September 2023 there will be a Stop Sell order, with BT no longer selling or upgrading ISDN or PSTN.

As of December 2025, all ISDN and PSTN services will cease to operate. There will also be no maintenance available on any of these types of circuits.

Who will be affected by the ISDN & PSTN switch off?

Over 16 million telephone lines will have to be transferred to IP-based networks which support broadband-based call services as a result of the switch off. This will affect over two million UK businesses, with the biggest impact felt by those with a substantial use of landline telephones, alarm systems and other telemetry-based services using PSTN lines (see below).

What will be affected by the PSTN and ISDN switch off?

A range of services will be affected by the switch off, including

  • Phone lines and their numbers
  • ADSL and FTTC broadband internet services
  • Door–entry systems / CCTV
  • Burglar alarms / Fire alarms / Panic alarms
  • Fax machines
  • Emergency phones / Emergency lift lines
  • EPOS terminals

How can a business prepare for the ISDN & PSTN switch off?

Today, there are plenty of other methods of voice and data transmission available that are cheaper, faster and more reliable.

To switch to an IP-based service, such as a VoIP or SIP solution, might sound like there’s a lot involved and a hassle you can do without, but these changes will be of great benefit to UK businesses. A business-grade hosted telephone service using VoIP revolutionises business communications. Advantages include reduced costs, excellent voice quality, flexibility, scalability and powerful functionality.

In order to get the right service for your business, it’s best to talk to a telecoms company that specialises in hosted telephony. Not only will they be able to assess your immediate needs but will also be able to offer you the scalability for your future requirements. Plus, they will be able to take all the hassle out of moving over to a new system, enabling you to keep your existing numbers and ensuring there is no impact on the day-to-day operation of the business.

Fail to prepare and you prepare to fail!

If you are a business whose voice and/or data transmission will be affected by the BT 2025 switch off, then it makes business sense to start planning the transition to hosted telephony now as the cut-off date is fast approaching.

During this transition period from your legacy systems to an internet service, upgrading your current legacy hardware including PBX’s may also be something to consider. Many of the older phone systems in offices today will need to be either replaced, upgraded or have additional components added to them to allow them to continue working over new IP Telephony lines.

Guidance from the Xcomm experts

The team at Xcomm are experts in the cloud telecoms field, providing hosted telephony services for many high profile customers and call centres. We have a whole range of solutions to meet the needs of all businesses, so why not take advantage of the ultimate telecommunications solutions we provide and embrace this change for the better before the rush when the final countdown begins.

Contact Xcomm to find out more on 03333 447 092 or email us at

Useful Glossary

ISDNIntegrated Service Digital Network, was the first version of high-speed internet. The service enables businesses to send data, such as voice calls or images, through their phone lines using the internet
PBXPrivate Branch Exchange (Telephone system)
PSTNPublic Switched Telephone Network is what you might refer to as the classic analogue telephone system – the system that enables landline connectivity. It generally consists of copper telephone lines, fibre optic cables, microwave transmission links, satellites, undersea telephone cables and mobile networks
VoIPVoice over Internet Protocol is a method of data transmission that allows for voice communications to be sent over the internet
SIPSession Initiation Protocol – The standard IP telephony signalling protocol used to start and terminate voice calls over the Internet
Hosted telephonyAn IP-based telephone system hosted in the cloud. It supports functionality such as transferring calls, call diversion, call waiting, call recording etc

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